Planetary reduction bearing arrangement

Abstract

A planetary deceleration bearing device comprises a bearing and a deceleration mechanism, the bearing comprises an outer ring, an inner ring and rolling bodies arranged between the outer ring and the inner ring, the deceleration mechanism comprises a sun gear, an inner ring gear, a planet carrier and planet gears, the bearing outer ring is integrally arranged with the inner ring gear, the bearing inner ring is integrally designed with the sun gear, the planet gears are arranged between the bearing outer ring and the bearing inner ring and are respectively engaged with the inner ring gear and the sun gear, and the planet carrier is fixed with the planet gears. The beneficial effects of the present application are that the bearing support function and the planetary deceleration mechanism transmission function are integrated at high integration by integrally arranging the bearing outer ring with the inner ring gear and integrally designing the bearing inner ring with the sun gear, the intermediate connecting flange and the transition piece required in the traditional separate arrangement are cancelled, the axial size of the device is significantly shortened and the radial volume is reduced, and the lightweight and compact requirement of humanoid robot joints can be better met.

Description

Technical Field

[0001] This invention relates to a joint module for a robot, and more particularly to a planetary reduction bearing device. Background Technology

[0002] With the development of humanoid robot technology, joint modules, as core components enabling flexible robot movement, are widely used in the rotational or swinging joints of humanoid robots, such as the shoulder, elbow, wrist, hip, knee, and ankle. When the robot performs actions such as walking, grasping, and turning, the joint module receives commands from the control system and transmits the rotational motion of the power source to the output end, thereby driving adjacent limbs to complete precise movements with predetermined angles and torques. Typically, a joint module consists of a motor, reducer, encoder, and output bearing, assembled sequentially along the axial direction to form an integrated drive unit, meeting the requirements of humanoid robots for high torque density and high responsiveness within a compact space.

[0003] Existing joint modules generally employ a separate structure for the drive source, reduction mechanism, and drive bearing. The power output from the drive source must be reduced and amplified by the reduction mechanism before being transmitted to the drive bearing to drive the external load. This step-by-step transmission method results in the functional components being stacked sequentially along the axial or radial direction, leading to a long overall axial dimension and a large radial volume. This makes it difficult to meet the increasingly stringent miniaturization and lightweight requirements of humanoid robot joints. Especially in multi-degree-of-freedom compact joint layouts, excessive structural volume restricts the biomimetic design of robot limbs, affecting motion flexibility and appearance envelope, thus hindering the further development of humanoid robots towards greater sophistication and integration. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a planetary reduction bearing device that reduces structural volume to meet the miniaturization requirements of humanoid robots.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: A planetary reduction bearing device includes a bearing and a reduction mechanism, wherein the reduction mechanism is a planetary reducer, the bearing includes an outer ring, an inner ring, and rolling elements disposed between the outer ring and the inner ring, the reduction mechanism includes a sun gear, an internal gear ring, a planet carrier, and planet gears, the outer ring of the bearing is integrally formed with the internal gear ring, the inner ring of the bearing is integrally formed with the sun gear, the planet gears are disposed between the outer ring and the inner ring of the bearing and mesh with the internal gear ring and the sun gear respectively, and the planet carrier is fixed to the planet gears.

[0006] The beneficial effects of this invention are as follows: By integrating the outer ring and internal gear ring of the bearing, and designing the inner ring and sun gear as a single unit, the bearing's supporting function and the planetary reduction mechanism's transmission function are integrated with a high degree of integration. This eliminates the intermediate connecting flanges and transition parts required in traditional separate arrangements, significantly shortening the axial dimension and reducing the radial volume of the device, thus better meeting the lightweight and compact requirements of humanoid robot joints. The planetary gears are directly arranged between the outer and inner rings of the bearing, utilizing the radial space between the inner and outer rings to simultaneously complete meshing transmission and rolling support, resulting in a more uniform load distribution and improved rigidity. As a preferred embodiment, the inner wall of the outer ring can be machined at one end to accommodate the rolling elements, and at the other end, the tooth profile of the internal gear ring can be directly formed. The outer wall of the inner ring is correspondingly formed with the sun gear tooth profile and raceway. The axial overlap of all components is minimal, further compressing space. As another preferred embodiment, the planetary carrier can be fixed or connected to output components as needed, enabling the device to both handle speed change and torque amplification and serve as the core rotary support of a rotating joint, demonstrating strong versatility.

[0007] Furthermore, the planetary carrier is fixed to the robot's body, and the inner ring is connected to the output end of the drive mechanism.

[0008] This design uses the planetary carrier as a fixed component. The torque output from the drive mechanism is transmitted to the sun gear through the inner ring, and then the planetary gears drive the outer ring, which is integrated with the internal gear ring, to achieve speed reduction and torque amplification. In this configuration, the inner ring is the input and the outer ring is the output, fully utilizing the bearing's inner and outer rings themselves as transmission elements. This eliminates the need for separate output flanges and support seats outside the module, resulting in fewer structural layers and a shorter transmission chain. This ensures high torque transmission while reducing the overall weight of the joint. The input and output are on the same axis, facilitating linear series connection in multi-degree-of-freedom joints and reducing offset bending moments. As a preferred approach, the inner wall of the center hole of the inner ring can be provided with rectangular or involute splines for direct insertion into the drive motor output shaft, ensuring backlash-free power transmission. The planetary carrier is rigidly secured to the robot's housing via evenly distributed screw holes or locating pin holes, ensuring the relative position of the gear meshing centers remains precisely unchanged.

[0009] Furthermore, the outer and inner rings are flush with their end faces along their axial direction toward the planet carrier, and a clearance fit is formed between the planet carrier and the outer and inner rings.

[0010] The outer and inner rings have flush end faces facing the planet carrier, providing a regular axial assembly reference for the planet carrier and facilitating control of the relative positions of the planet gears and the inner and outer rings during assembly. A pre-set gap is maintained between the planet carrier and the rings to prevent contact friction between the outer and inner ring end faces and the fixed planet carrier during operation. This eliminates additional resistance torque and wear caused by mechanical interference, allowing the device to maintain low power loss and stable temperature rise even under high-speed or reversible operation. As a preferred embodiment, an annular clearance groove can be formed in the area of ​​the planet carrier corresponding to the outer and inner ring end faces, connecting to the planet gear shaft only through the central area or several radial spokes, resulting in a uniform clearance space across the entire end face area. Alternatively, a wear-resistant plastic washer with a trapezoidal or wavy cross-section can be placed in the gap to provide flexible restraint for accidental minor axial movement without significantly increasing friction.

[0011] Furthermore, the outer ring includes a first raceway region that mates with the rolling element and an internal gear ring region thereon, wherein the width ratio of the first raceway region and the internal gear ring region along the bearing axial direction is 0.55-0.65.

[0012] The outer ring is divided axially into a raceway region and an internal gear ring region, with a reasonable ratio. This allows the same component to provide sufficient rolling element bearing length to ensure bearing life and static load capacity without increasing axial length and diameter, while also providing a sufficiently wide tooth surface for the internal gear ring to resist contact stress from torque, preventing premature pitting or breakage. The integrated structure eliminates the connection interface between the raceway and gear ring components, allowing for smooth transitions with large-radius fillets, which helps alleviate stress concentration. As a preferred approach, the first raceway region can be induction hardened to form a hardened layer, while the tooth surface of the internal gear ring region can be carburized and quenched or laser-strengthened, giving different functional parts of the outer ring differentiated hardness and wear resistance. As another preferred approach, the internal gear ring region can be designed with helical or herringbone teeth, allowing for smooth meshing with multiple planetary gears and generating an effect of offsetting axial force components, improving transmission smoothness and load distribution.

[0013] Furthermore, the inner ring includes a second raceway region that mates with the rolling elements and a sun gear region on which the sun gear is disposed, wherein the width ratio of the second raceway region and the sun gear region along the bearing axial direction is 0.55-0.65.

[0014] The functional area division and proportional setting of the inner ring ensures that the sun gear has sufficient tooth width to reliably mesh with the planetary gears and transmit the maximum input torque. Simultaneously, the second raceway area maintains a contact length adapted to the rolling elements, preventing insufficient raceway length, uneven wear of the rolling elements, or stress concentration due to excessive sun gear tooth width encroachment. The integrated structure of the inner and outer ring raceways and transmission teeth helps reduce the number of parts and enhances overall rigidity, enabling the joint module to maintain high resistance to deformation under bending moment. As a preferred embodiment, the outer teeth of the sun gear area can be precision forged and then ground to achieve high precision, while the second raceway area uses bearing-grade precision grinding, ensuring excellent surface quality in both functional areas. Furthermore, the interface is provided with a relief groove or a step with a transition fillet to prevent heat treatment distortion and crack initiation. As another preferred embodiment, the central through-hole of the inner ring can be connected to the drive shaft using a conical surface fit with a locking nut, achieving a self-centering, backlash-free connection and ensuring precise and stable sun gear meshing position.

[0015] Furthermore, the end face of the planetary gear facing the rolling element along the bearing axis forms a clearance fit with the first raceway region or the second raceway region.

[0016] Maintaining a non-contact clearance between the axial end face of the planetary gear and the raceway areas of the inner and outer rings eliminates abnormal scraping between the sidewalls of the planetary gear and the raceway shoulders during revolution and rotation, avoiding problems such as frictional noise, overheating, and wear debris contamination of the lubricating medium. This is particularly crucial for maintaining stable transmission efficiency in robot joints with frequent starts, stops, and reversals. As a preferred embodiment, the end face of the planetary gear can be machined with an annular recess or a thinned section with a slightly smaller diameter near the raceway to increase the local clearance; simultaneously, the axial end edges of the first and second raceway areas can be chamfered or have arc-shaped edges to further expand the clearance space. As another preferred embodiment, an elastic wave spring can be floatingly configured in the gap between the planetary gear and the raceway area. This spring does not make contact during normal operation, but only provides flexible cushioning under axial displacement caused by extreme impacts, avoiding rigid collisions. Attached Figure Description

[0017] Figure 1 This is a structural diagram of an embodiment of the present invention. Figure 2 This is a cross-sectional view of an embodiment of the present invention; Figure 3 This is a schematic diagram of the outer ring structure in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure after removing the outer ring in an embodiment of the present invention. Detailed Implementation

[0018] An embodiment of the present invention provides a planetary reduction bearing device, such as... Figure 1-4As shown, this device integrates the bearing and reduction mechanism, significantly reducing the structural volume. The outer ring 2 and inner ring 3 of the bearing are coaxially arranged, with rolling elements 4 positioned between them, allowing the outer ring 2 and inner ring 3 to rotate relative to each other and withstand radial and axial loads. The reduction mechanism adopts a planetary reducer structure, with its sun gear 31 integrated with the inner ring 3 of the bearing, which can be directly machined from the sun gear area onto the outer circumferential surface of the inner ring 3. The internal gear ring 21 is integrated with the outer ring 2 of the bearing, located on the inner circumferential surface of the outer ring 2. Planetary gears 5 are arranged in the annular space between the outer ring 2 and inner ring 3, meshing with both the internal gear ring 21 and the sun gear 31 to transmit power and achieve speed reduction and torque increase. The planetary carrier 6 is fixed to all planetary gears 5, providing circumferential positioning and support for the planetary gears 5. The planetary carrier 6 is also used to fix the planetary reducer to the robot's body, resulting in a transmission configuration where the planetary carrier is fixed, the sun gear is the input, and the internal gear ring is the output. In this structure, the outer ring 2 and inner ring 3 are flush with their axial end faces towards the planet carrier 6. The planet carrier 6 forms a clearance fit with both the outer ring 2 and inner ring 3, thus preventing them from abutting against the rotating parts of the bearing and increasing frictional resistance. The outer ring 2 is axially divided into a first raceway region 22 that mates with the rolling elements 4 and an internal gear region 21 where the internal gear ring 21 is located. The width ratio of the first raceway region 22 and the internal gear region 21 along the bearing axial direction is controlled between 0.55 and 0.65. Correspondingly, the inner ring 3 is axially divided into a second raceway region 32 that mates with the rolling elements 4 and a sun gear region 31 where the sun gear 31 is located. The width ratio of the second raceway region 32 and the sun gear region 31 along the bearing axial direction is also controlled between 0.55 and 0.65, ensuring a reasonable axial proportion between the bearing support portion and the gear transmission portion, guaranteeing a balance between load-bearing and transmission performance. The end face of the planetary gear 5 facing the rolling element 4 along the bearing axis also forms a clearance fit with the first raceway region 22 or the second raceway region 32, further preventing interference with the normal operation of the rolling element 4. The inner ring 3 serves as the input end of the entire joint module and is connected to the output end of the drive mechanism, while the outer ring 2 serves as the output end. The planetary reduction structure amplifies the speed increase and torque of the input to the inner ring 3 before outputting it to the outer ring 2.

[0019] The working principle of this embodiment is as follows: The drive mechanism drives the inner ring 3 to rotate, and the integrated sun gear 31 on the inner ring 3 rotates synchronously. The sun gear 31 drives the planetary gears 5 meshing with it to rotate. Since the planet carrier 6 is fixed to the robot body and remains stationary, the planetary gears 5 can only rotate in place and cannot revolve around the sun gear 31. This forces the internal gear ring 21 meshing with the planetary gear 5 and the outer ring 2 integrated with the internal gear ring 21 to rotate in the opposite direction at a lower speed than the inner ring 3, thereby achieving a reduction in the input speed and a multiple amplification of the torque. The power is then output to the joint actuators by the outer ring 2. The rolling element 4 between the inner ring 3 and the outer ring 2 provides rolling support when they rotate relative to each other, bearing radial and axial loads and reducing frictional resistance. The clearance fit between the planet carrier 6 and the outer ring 2 and the inner ring 3, as well as the clearance fit between the end face of the planetary gears 5 and the first raceway region 22 or the second raceway region 32, avoids unnecessary contact between moving parts, effectively reducing frictional resistance during operation and improving transmission efficiency.

[0020] The above embodiments are merely one preferred embodiment of the present invention. Ordinary variations and substitutions made by those skilled in the art within the scope of the technical solution of the present invention are all included within the protection scope of the present invention.

Claims

1. A planetary reduction bearing device, comprising a bearing and a reduction mechanism, wherein the reduction mechanism is a planetary reducer, and the bearing comprises an outer ring, an inner ring, and rolling elements disposed between the outer ring and the inner ring, characterized in that: The bearing and the reduction mechanism are integrated. The reduction mechanism includes a sun gear, an internal gear ring, a planet carrier, and planet gears. The outer ring of the bearing is integrated with the internal gear ring, and the inner ring of the bearing is integrated with the sun gear. The planet gears are located between the outer ring and the inner ring of the bearing and mesh with the internal gear ring and the sun gear, respectively. The planet carrier is fixed to the planet gears.

2. The planetary reduction bearing device according to claim 1, characterized in that: The planetary carrier is fixed to the robot's body, and the inner ring is connected to the output end of the drive mechanism.

3. The planetary reduction bearing device according to claim 1, characterized in that: The outer and inner rings are flush with their axial ends facing the planet carrier, and the planet carrier forms a clearance fit with the outer and inner rings.

4. The planetary reduction bearing device according to claim 1, characterized in that: The outer ring includes a first raceway region that mates with the rolling elements and an internal gear ring region thereon, wherein the width ratio of the first raceway region and the internal gear ring region along the bearing axial direction is 0.55-0.

65.

5. The planetary reduction bearing device according to claim 4, characterized in that: The inner ring includes a second raceway region that mates with the rolling elements and a sun gear region on which the sun gear is disposed. The ratio of the width of the second raceway region and the sun gear region along the bearing axial direction is 0.55-0.

65.

6. The planetary reduction bearing device according to claim 4 or 5, characterized in that: The end face of the planetary gear facing the rolling element along the bearing axis forms a clearance fit with the first raceway region or the second raceway region.

Images