A planetary gear reducer, a rotary joint for a robot, and a robot

Abstract

The application provides a planetary gear reducer, which comprises a left planetary gear set, a right planetary gear set, a middle planetary gear set and a support ring set. The left planetary gear set and the right planetary gear set are symmetrically arranged and are respectively engaged with the middle planetary gear set in the middle to balance each other, so that each planetary gear in the left planetary gear set and the right planetary gear set can be kept in alignment without a planetary carrier, and meanwhile, an inner reaction ring is used to position the planetary gears from the inner side. An output part is supported on the planetary gear set through non-sliding rolling contact between the rolling ring surface of the output part and the supporting surface of each planetary gear, so that a special output bearing is omitted. Moreover, the planetary gear reducer is arranged between two walls of a frame to obtain rigidity, and is integrated into a transmission component with high torque density, compactness and reliability and low cost.

Description

Technical Field

[0001] This application relates to the field of power transmission technology, specifically to a planetary gear reducer, a rotary joint for a robot, and a robot. Background Technology

[0002] Compound planetary gear transmissions can achieve high transmission ratios in a single compact gear set, making planetary gear reducers a common choice for robot actuators.

[0003] In traditional planetary gear transmissions, planetary gears are supported by bearings mounted in planet carriers. This leads to high precision requirements, directly increasing manufacturing costs. Furthermore, to ensure the normal operation of the planetary gear transmission, additional planet carriers and bearings are added, further increasing the size and weight of the mechanism. Moreover, the presence of multiple bearings can cause power loss due to bearings, and bearings, as high-precision components, are prone to wear and failure, becoming weak links that can cause the entire mechanism to malfunction.

[0004] In addition, the output component connected to the planetary gear transmission is usually installed at one axial end of the transmission device in a cantilevered state. This structure concentrates all external loads at a single support position and is borne by a crossed roller bearing (or similar bearing), which significantly increases the stress on weak links such as bearings, further accelerating mechanism failure and weakening the reliability of the mechanism.

[0005] For robot actuators, it is required to have high torque density, compactness, reliability, transmission efficiency and rigidity at low cost, and a sufficiently long service life; obviously, the existing planetary gear reducers mentioned above have obvious shortcomings when applied to robot actuators.

[0006] Therefore, how to reduce the number of components in a composite planetary gear transmission device to lower the complexity and cost of high-precision manufacturing, while still possessing the characteristics of high torque density, compactness, reliability, transmission efficiency, and rigidity, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] This application provides a planetary gear reducer to solve the problem in the prior art of how to reduce the number of parts in a composite planetary gear transmission device to reduce the complexity and cost of high-precision manufacturing, while still possessing the characteristics of high torque density, compactness, reliability, transmission efficiency, and rigidity.

[0008] This application provides a planetary gear reducer, including a left planetary gear set and a right planetary gear set arranged in corresponding relative positions, an intermediate planetary gear set located between the left planetary gear set and the right planetary gear set, and a support ring group composed of multiple support rings; The left internal gear ring of the left planetary gear set and the right internal gear ring of the right planetary gear set are opposite to each other and fixed to the first arm and the second arm opposite to each other on the first frame. The axis of the left sun gear of the left planetary gear set and the axis of the right sun gear of the right planetary gear set are connected by a first connecting shaft. The axis of the left planet gear of the left planetary gear set and the axis of the right planet gear of the right planetary gear set are connected by a second connecting shaft. The intermediate planetary gear set includes an intermediate internal gear ring and intermediate planetary gears, wherein the intermediate planetary gears of the intermediate planetary gear set are fixedly mounted on the second connecting shaft; the intermediate internal gear ring of the intermediate planetary gear set is fixedly mounted on the output component; The support ring assembly includes a central support ring sleeved on the first connecting shaft and a planetary support ring installed through the second connecting shaft; wherein, the outer diameter surface of the central support ring abuts against the outer diameter surface of the planetary support ring, and the outer diameter surface of the planetary support ring also abuts against the inner diameter surface of the intermediate internal gear ring coaxially arranged, thereby realizing the rotational support of the intermediate internal gear ring of the intermediate planetary gear assembly relative to the first connecting shaft.

[0009] Optionally, the support ring group includes a first support ring group and a second support ring group arranged on the left and right sides of the intermediate planetary gear set.

[0010] Optionally, the outer diameter surface of the planetary support ring is located on the cylindrical surface formed by the vertical projection of the pitch circle of the coaxially arranged intermediate planetary gear; the inner diameter surface of the support ring coaxially arranged is located on the cylindrical surface formed by the vertical projection of the pitch circle of the intermediate internal gear ring.

[0011] Optionally, the left planetary gear of the left planetary gear set and the right planetary gear of the right planetary gear set are respectively arranged in two or more symmetrically about the first connecting shaft.

[0012] Optionally, the left planetary gear of the left planetary gear set and the right planetary gear of the right planetary gear set have the same number of teeth and module.

[0013] Optionally, the output component is connected to a second frame, and the second frame and the first frame are kinematically coupled through the planetary gear reducer, and can rotate relative to each other within a set angle range.

[0014] Optionally, the second connecting shaft extends axially at both ends and exceeds the outer end faces of the left planetary gear of the left planetary gear set and the right planetary gear of the right planetary gear set, respectively; a left outer support ring is installed on the extended shaft exceeding the outer end face of the left planetary gear of the left planetary gear set, and the left outer support ring abuts against the inner diameter surface of the left outer rolling ring coaxially arranged with the left internal gear ring of the left planetary gear set; a right outer support ring is installed on the extended shaft exceeding the outer end face of the right planetary gear of the right planetary gear set, and the right outer support ring abuts against the inner diameter surface of the right outer rolling ring coaxially arranged with the right internal gear ring of the right planetary gear set.

[0015] This application also provides a rotary joint for a robot, the rotary joint including a base and a movable part that are rotatable relative to each other within a set angle range, and a planetary gear reducer connecting the base and the movable part as described above; wherein, a first frame is disposed on the base, the intermediate planetary gear set is fixed to the movable part by its internal gear ring; a drive motor is mounted on the outside of the sun gear of the left or right planetary gear set, and its output shaft is connected to the sun gear shaft.

[0016] This application also provides a robot whose rotary joint employs the rotary joint described above for robots.

[0017] Compared with the prior art, this application has the following advantages: This application provides a planetary gear reducer, including a left planetary gear set and a right planetary gear set arranged in corresponding positions, an intermediate planetary gear set located between the left and right planetary gear sets, and a support ring group composed of multiple support rings. The left internal gear ring of the left planetary gear set and the right internal gear ring of the right planetary gear set are opposite each other and respectively fixed to the first arm and the second arm of the first frame. The shafts of the left sun gear of the left planetary gear set and the right sun gear of the right planetary gear set are connected by a first connecting shaft, and the shafts of the left planet gear of the left planetary gear set and the right planet gear of the right planetary gear set are connected by a second connecting shaft. The intermediate planetary gear set includes an intermediate internal gear ring and intermediate planet gears, wherein the intermediate planet gears of the intermediate planetary gear set are fixedly mounted on the second connecting shaft, and the intermediate internal gear ring of the intermediate planetary gear set is fixedly mounted on the output component. The support ring assembly includes a central support ring fitted on a first connecting shaft and planetary support rings mounted via a second connecting shaft. The central support ring is loosely fitted on the first connecting shaft, and its outer diameter surface abuts against the outer diameter surface of the planetary support ring. The outer diameter surface of the planetary support ring also abuts against the inner diameter surface of a rolling ring coaxially arranged with the intermediate internal gear ring, thereby achieving rotational support for the intermediate internal gear ring of the intermediate planetary gear assembly relative to the first connecting shaft.

[0018] The planetary gear reducer provided in this application achieves left-right balance by symmetrically arranging left and right planetary gear sets, which respectively engage with the central planetary gear set. With the support of the support ring group, the planetary gears in the left and right planetary gear sets can maintain alignment without a planet carrier. The output component provides support for the planetary gears through the abutting fit between the inner diameter surface of the rolling ring coaxial with the central internal gear ring and the outer diameter surface of each planetary support ring, thus eliminating the need for a dedicated output bearing. Under reasonable design, the aforementioned abutting contact surface can theoretically achieve non-slip rolling contact, minimizing friction. Furthermore, this design transforms the component bearing the external load into a larger component, which has a stronger ability to withstand cyclic load stress, thereby solving the weakest link in the original mechanism and significantly improving the overall reliability of the mechanism. In practical robot applications, the planetary gear reducer is mounted between the two walls of the frame to obtain rigidity, thus combining with the robot scenario to obtain a transmission component with high torque density, compactness, reliability, and low cost. Attached Figure Description

[0019] Figure 1 This is a perspective view of a planetary gear reducer provided in an embodiment of this application.

[0020] Figure 2 This is a cross-sectional view of a planetary gear reducer provided in an embodiment of this application.

[0021] Figure 3 This is a schematic diagram of a planetary gear reducer provided in an embodiment of this application. The schematic diagram only shows the upper half of the planetary gear reducer.

[0022] Figure 4 This is a schematic diagram of another planetary gear reducer provided in the embodiments of this application. The schematic diagram only shows the upper half of the planetary gear reducer.

[0023] Figure 5 This is a schematic diagram of the planetary gear reducer assembled on the frame according to an embodiment of this application.

[0024] Figure 6 This is a schematic diagram of one side of the output arm that is integrated with the output component, as provided in an embodiment of this application.

[0025] Figure 7 This is a schematic diagram of the rack structure provided in the embodiment of this application.

[0026] Figure label: Planetary gear reducer 10, left internal gear ring 11, left planetary gear 12, left sun gear 13, right internal gear ring 21, right planetary gear 22, right sun gear 23, first connecting shaft 31, second connecting shaft 32, middle internal gear ring 41, middle planetary gear 42, center support ring 51, planetary support ring 52, rolling ring 53, first rolling ring 53-1, second rolling ring 53-2, left outer rolling ring 54-1, right outer rolling ring 54-2, left outer support ring 61, right outer support ring 62, output component 7, frame 8, first arm 81, second arm 82, connecting hole 83, rotary joint 20, input arm 30, output arm 40, thrust washer 50, sealing structure 51. Detailed Implementation

[0027] Many specific details are set forth in the following description to provide a full understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this application; therefore, this application is not limited to the specific embodiments disclosed below.

[0028] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0030] Compound planetary gear transmissions can achieve high transmission ratios in a single compact gear set, and are therefore widely used in the implementation of robot actuators.

[0031] In traditional planetary gear transmissions, planetary gears are supported by bearings mounted in the planet carrier. The need to use multiple high-precision bearings increases manufacturing costs. The additional parts also increase the size and weight of the mechanism. The presence of multiple bearings also increases power loss and becomes a weak link that is prone to failure.

[0032] Furthermore, the output component connected to the planetary gear transmission is typically mounted on one axial end of the transmission, extending in a cantilevered state. This concentrates all external loads on a single support location, borne by a crossed roller bearing (or similar bearing). This causes periodic stress to concentrate on the relatively weak bearing during operation, increasing the likelihood of bearing failure. Robot actuators require high torque density, compactness, reliability, transmission efficiency, and rigidity at low cost, requirements that existing reducers using traditional planetary gear transmissions clearly cannot fully meet.

[0033] In view of this, this application provides a planetary gear reducer, including a left planetary gear set and a right planetary gear set arranged in corresponding positions, an intermediate planetary gear set located between the left and right planetary gear sets, and a support ring group composed of multiple support rings. The left internal gear ring of the left planetary gear set and the right internal gear ring of the right planetary gear set are opposite each other and respectively fixed to the first arm and the second arm of the first frame. The shaft of the left sun gear of the left planetary gear set and the shaft of the right sun gear of the right planetary gear set are connected by a first connecting shaft, and the shafts of the left planet gear of the left planetary gear set and the right planet gear of the right planetary gear set are connected by a second connecting shaft. The intermediate planetary gear set includes an intermediate internal gear ring and intermediate planet gears, wherein the intermediate planet gears of the intermediate planetary gear set are fixedly mounted on the second connecting shaft, and the intermediate internal gear ring of the intermediate planetary gear set is fixedly mounted on the output component. The support ring assembly includes a central support ring sleeved on the first connecting shaft and a planetary support ring installed through the second connecting shaft. The outer diameter surface of the central support ring abuts against the outer diameter surface of the planetary support ring, and the outer diameter surface of the planetary support ring also abuts against the inner diameter surface of the rolling ring coaxially arranged with the intermediate internal gear ring, thereby realizing the rotational support of the intermediate internal gear ring of the intermediate planetary gear set relative to the first connecting shaft.

[0034] The planetary gear reducer provided in this application achieves left-right balance by symmetrically arranged left and right planetary gear sets that mesh with a central planetary gear set. Furthermore, the support rings ensure that the planetary gears in the left and right planetary gear sets remain aligned without a planet carrier. The output component provides support to the planetary gears through a non-slip rolling contact between the inner diameter surface of a rolling ring coaxial with the central internal gear ring and the outer diameter surface of each planetary support ring, thus eliminating the need for a dedicated output bearing. In practical robot applications, the planetary gear reducer is mounted between the two walls of the frame to achieve rigidity, thus integrating with the robot's design to create a transmission component with high torque density, compactness, reliability, and low cost.

[0035] The planetary gear reducer provided in this application will now be described in detail with reference to the accompanying drawings. Figure 1 This is a perspective view of a planetary gear reducer provided in an embodiment of this application. Figure 2 This is a cross-sectional view of a planetary gear reducer provided in an embodiment of this application. Figure 3 This is a schematic diagram of a planetary gear reducer provided in an embodiment of this application. The schematic diagram only shows the upper half of the planetary gear reducer, and the lower half is symmetrically arranged with the upper half. Figure 4 This is a schematic diagram of another planetary gear reducer provided in the embodiments of this application. The schematic diagram only shows the upper half of the planetary gear reducer, and the lower half is symmetrically arranged with the upper half. Figure 5 This is a schematic diagram of the planetary gear reducer assembled on the frame according to an embodiment of this application. Figure 6 This is a schematic diagram of the output arm integrated with the output component provided in an embodiment of this application. Figure 7 This is a schematic diagram of the rack structure provided in the embodiment of this application.

[0036] First Embodiment like Figures 1 to 7 As shown, this application provides a planetary gear reducer 10, including a left planetary gear set and a right planetary gear set arranged in corresponding positions, an intermediate planetary gear set located between the left and right planetary gear sets, and a support ring group composed of multiple support rings. The left internal gear ring 11 of the left planetary gear set and the right internal gear ring 21 of the right planetary gear set are opposite each other and fixed to the first arm 81 and the second arm 82 of the frame 8, respectively. In this embodiment, the first arm 81 and the second arm 82 are opposite each other and arranged parallel to each other. The axis of the left sun gear 13 of the left planetary gear set and the axis of the right sun gear 23 of the right planetary gear set are connected by a first connecting shaft 31, and the axis of the left planet gear 12 of the left planetary gear set and the axis of the right planet gear 22 of the right planetary gear set are connected by a second connecting shaft 32. The intermediate planetary gear set includes an intermediate internal gear ring 41 and intermediate planet gears 42, wherein the intermediate planet gear 42 of the intermediate planetary gear set is fixedly mounted on the second connecting shaft 32, and the intermediate internal gear ring 41 of the intermediate planetary gear set is fixedly mounted on the output component 7. The support ring assembly includes a central support ring 51 sleeved on the first connecting shaft 31 and a planetary support ring 52 mounted via the second connecting shaft 32. The outer diameter surface of the central support ring 51 abuts and rolls with the outer diameter surface of the planetary support ring 52. The outer diameter surface of the planetary support ring 52 also engages with the inner diameter surface of the rolling ring 53 coaxially arranged with the intermediate internal gear ring 41, thereby achieving rotational support for the intermediate internal gear ring 41 of the intermediate planetary gear set relative to the first connecting shaft 31.

[0037] Specifically, in this embodiment, the left planetary gear set and the right planetary gear set are arranged symmetrically; and the left planetary gear 12 of the left planetary gear set and the right planetary gear 22 of the right planetary gear set are arranged symmetrically with the first connecting shaft 31 as the center, with two or more of them respectively.

[0038] Furthermore, the left planetary gear set includes a left internal ring gear 11, left planet gears 12, and a left sun gear 13, wherein the left sun gear 13 is located at the center of the left planetary gear set. The left planetary gear set includes four left planet gears 12, which are arranged around a left sun gear 13. These left planet gears 12 mesh with the left sun gear 13, and they also mesh with the left internal ring gear 11. The left internal ring gear 11 is fixed to the first arm 81 of the frame 8, and in the axial direction, the left internal ring gear 11 is located on the outer side of the output component 7. The right planetary gear set includes a right internal ring gear 21, right planet gears 22, and a right sun gear 23. Correspondingly, the right planetary gear set includes four right planet gears 22, which are arranged around a right sun gear 23, and these right planet gears 22 mesh with the right sun gear 23, and they also mesh with the right internal ring gear 21. The right internal gear ring 21 is fixed to the second arm 82 of the frame 8, and in the axial direction, the right internal gear ring 21 is located on the outer side of the output component 7.

[0039] In this embodiment, the axis of the left sun gear 13 of the left planetary gear set and the axis of the right sun gear 23 of the right planetary gear set are connected by a first connecting shaft 31, and the axes of the left planet gears 12 of the left planetary gear set and the corresponding axes of the right planet gears 22 of the right planetary gear set are connected by corresponding second connecting shafts 32. Since there are four left planetary gears and four right planetary gears, in this example, there is one first connecting shaft 31 and four second connecting shafts 32. The axes of the first connecting shaft 31 and the second connecting shaft 32 are parallel. In one example, the first connecting shaft 31 has a central axial hole for cable routing, and the first connecting shaft 31 is rotatable about the transmission axis A.

[0040] Furthermore, in one example, in the axial direction, the first connecting shaft 31 includes a first end and a second end, and the second connecting shaft 32 includes a third end and a fourth end. Taking the first connecting shaft 31 and the second connecting shaft 32 as an example, the left sun gear 13 of the left planetary gear set is fixedly disposed at the first end of the first connecting shaft 31, the left planet gear 12 of the left planetary gear set is fixedly disposed at the third end of the second connecting shaft 32, the right sun gear 23 of the right planetary gear set is fixedly disposed at the second end of the first connecting shaft 31, and the right planet gear 22 of the right planetary gear set is fixedly disposed at the fourth end of the second connecting shaft 32. In another example, the left sun gear 13 and the right sun gear 23 can be manufactured on the same part as the first connecting shaft 31, and the left planet gear 12 and the right planet gear 22 can be manufactured on the same part as the second connecting shaft 32.

[0041] In this embodiment, the intermediate planetary gear set is located between the left and right planetary gear sets in the axial direction. Specifically, the intermediate planetary gear set includes an intermediate internal gear ring 41 and intermediate planetary gears 42. The intermediate planetary gears 42 are fixedly mounted on the second connecting shaft 32, and the intermediate internal gear ring 41 is fixedly mounted on the output component 7. The external teeth of the intermediate planetary gears 42 mesh with the internal teeth of the intermediate internal gear ring 41. In this embodiment, the intermediate planetary gears 42 are correspondingly arranged with the left planetary gear 12 of the left planetary gear set and the right planetary gear 22 of the right planetary gear set, that is, the same number is provided, and two or more are symmetrically arranged with the first connecting shaft 31 as the center.

[0042] In this embodiment, the rotation of the left sun gear 13 and the right sun gear 23 drives the left planet gear 12 and the right planet gear 22 respectively. The left planet gear 12 and the right planet gear 22 mesh with the fixed left internal gear ring 11 and the right internal gear ring 21 to obtain support and motion constraint. The rotation of the left planet gear 12 and the right planet gear 22 drives the intermediate planet gear 42 to move together, and through the meshing of the intermediate planet gear 42 with the intermediate internal gear ring 41, it drives the rotation of the intermediate internal gear ring 41. The above gear meshing relationship allows the high speed obtained by the left sun gear 13 and the right sun gear 23 from the drive motor to obtain a significantly reduced speed in the intermediate internal gear ring 41 through the high reduction ratio of the planetary gear system, and drives the output component 7 connected to the intermediate internal gear ring 41 to move accordingly.

[0043] In the aforementioned reduction meshing, each left planetary gear 12 and right planetary gear 22 is symmetrically loaded onto the mid-plane through the meshing of its corresponding left sun gear 13, right sun gear 23, left internal gear ring 11, and right internal gear ring 21, and outputs from the mid-plane to the intermediate planetary gear 42 and intermediate internal gear ring 41, thus providing the intermediate planetary gear set with a balanced drive input. Therefore, each left planetary gear 12, right planetary gear 22, and intermediate planetary gear 42 maintains balance and alignment with axis A through the symmetry of the meshing relationship of the entire system, eliminating the need for a planet carrier for balance and separate bearings to support their rotation. In this way, by eliminating the planet carrier and separate planetary gear bearings, the planetary gear reducer 10 avoids high-precision manufacturing costs, reduces the number of parts, size, and weight, and avoids bearing power loss and failure, thereby improving torque density, compactness, efficiency, and reliability at a lower cost.

[0044] In this embodiment, the support ring assembly includes a central support ring 51 sleeved on the first connecting shaft 31 and a planetary support ring 52 mounted via the second connecting shaft 32. The outer diameter surface of the central support ring 51 abuts against the outer diameter surface of the planetary support ring 52, and the outer diameter surface of the planetary support ring 52 also abuts against the inner diameter surface of the rolling ring 53 coaxially arranged with the intermediate internal gear ring 41, thereby achieving rotational support for the internal gear ring of the intermediate planetary gear set relative to the first connecting shaft 31. The outer diameter surface of the planetary support ring 52 lies on the cylindrical surface formed by the vertical projection of the pitch circle of the coaxially arranged intermediate planetary gear 42; the inner diameter surface of the rolling ring 53 coaxially arranged with the intermediate internal gear ring 41 lies on the cylindrical surface formed by the vertical projection of the pitch circle of the intermediate internal gear ring 41. By selecting these parameters, the outer diameter surface of the central support ring 51 and the outer diameter surface of the planetary support ring 52 can be in a rolling fit during movement. The outer diameter surface of the planetary support ring 52 can also be in a rolling fit with the inner diameter surface of the rolling ring 53, which is coaxially arranged with the intermediate internal gear ring 41, during movement. This rolling fit ensures smooth operation of the entire mechanism and significantly reduces frictional losses.

[0045] Furthermore, the support ring assembly includes a first support ring assembly and a second support ring assembly arranged on the left and right sides of the intermediate planetary gear set. The first and second support ring assemblies have the same structure. Specifically, in one example, the first support ring assembly is described as follows: the first support ring assembly includes a central support ring 51 and multiple planetary support rings 52; wherein the central support ring 51 is fitted onto the left half of the first connecting shaft 31, and its planetary support rings 52 are correspondingly arranged on the left half of the second connecting shaft 32. Correspondingly, the central support ring 51 of the second support ring assembly is symmetrically fitted onto the right half of the first connecting shaft 31, and its planetary support rings 52 are correspondingly arranged on the right half of the second connecting shaft 32.

[0046] In one example, helical or herringbone teeth can be used at selected meshing points to enable axial self-centering of planetary gears without planet carriers, but this increases manufacturing and assembly difficulty due to the cutting teeth of the helical or herringbone teeth and the required timing of axial engagement of the planetary gears. Alternatively, the support ring assembly also includes a rolling ring 53 coaxially arranged with the internal gear ring of the intermediate planetary gear set. The outer diameter surface of the planetary support ring 52 mates with the inner diameter surface of the rolling ring 53. In one example, the rolling ring 53 includes a first rolling ring 53-1 and a second rolling ring 53-2 arranged on the left and right sides of the intermediate planetary gear set. The sidewalls of the first rolling ring 53-1 and the second rolling ring 53-2 can limit the axial direction of the intermediate planetary gear set, thereby avoiding the use of helical or herringbone teeth for axial self-centering of the planetary gears and reducing the difficulty of parts machining.

[0047] In this embodiment, the planetary support ring 52 is directly connected to the inner diameter surface of the rolling ring 53 via rolling contact. When the intermediate planetary gear 42 revolves and rotates, the outer diameter surface of the planetary support ring 52 rolls on the inner diameter surface of the rolling ring 53, thereby enabling the output component 7 to be supported by the contact between the planetary support ring 52 and the rolling ring 53. Rotational motion is achieved through the meshing relationship of the balanced left planetary gear set, right planetary gear set, and intermediate planetary gear set. The support of the output component 7 by the planetary support ring 52 and the rolling ring 53 is not limited to the symmetrical embodiment without a planetary carrier; it can also be applied to traditional composite planetary transmissions with planetary carriers, supporting the output component 7 without a dedicated output bearing through the rolling contact between the planetary support ring 52 and the rolling ring 53.

[0048] In one example, each planetary support ring 52 is located at the pitch circle of the intermediate planetary gear 42, and the inner diameter surface of each rolling ring 53 is located at the pitch circle of the intermediate internal gear ring 41. Under these conditions, the contact between the planetary support ring 52 and the rolling ring 53 can be in a pure rolling state without slippage. The central support ring 51 is located on the first connecting shaft 31, and the outer diameter surface of the central support ring 51 is in rolling contact with the outer diameter surface of the planetary support ring 52. The central support ring 51 and the planetary support ring 52 are theoretically in a pure rolling fit state at the contact position, thereby obtaining a smaller friction loss.

[0049] Under operating torque, the radial forces of the left planetary gear 12, right planetary gear 22, left internal gear ring 11, right internal gear ring 21, and intermediate internal gear ring 41 and intermediate planetary gear 42 cause each planetary gear to move radially inward. The central support ring 51 acts radially inward on the planetary support ring 52 to withstand this inward radial force, while the rolling ring 53, which contacts the output member 7, acts radially outward on the planetary support ring 52. These contacts are preferably located at two or more axial positions, clamping each planetary gear (including the left planetary gear 12 and right planetary gear 22) from both sides, thereby stabilizing the center distance and tilt angle of each planetary gear and balancing the load among the planetary gears through a symmetrical structural arrangement. The determined center distance coincides with the pitch circle center distance of the meshing, maintaining correct full-tooth surface contact without constraint.

[0050] Each left planetary gear 12 and right planetary gear 22 is radially positioned on both sides in the same manner by its own gear meshing. Its inner radial tooth surfaces mesh with the left sun gear 13 and right sun gear 23, and its outer radial tooth surfaces mesh with the left internal gear ring 11 and right internal gear ring 21—thus, these two meshing points clamp the planetary gears radially from both sides at each end position, just as the central support ring 51 and rolling ring 53 clamp the planetary support ring 52 at the middle position. Thus, the left sun gear 13 and right sun gear 23, and the left internal gear ring 11 and right internal gear ring 21 constrain the radial position of each left planetary gear 12 and right planetary gear 22 relative to the left internal gear ring 11 and right internal gear ring 21, ensuring that each left planetary gear 12 and right planetary gear 22 maintains proper meshing with the left internal gear ring 11 and right internal gear ring 21. This meshing is precisely the path through which the planetary gears transmit radial loads, and, in conjunction with the central rolling clamping, positions the planetary gears without a planetary carrier along their entire length.

[0051] Because the radial load is borne by rolling on both sides of the planetary gears (the outer planetary support ring 52 and rolling ring 53 contact each other, and the inner center support ring 51 and planetary support ring 52 contact each other), the output component 7 is radially supported entirely by the balanced left and right planetary gear sets themselves. Each second connecting shaft 32 is positioned at its correct meshing center distance via this same rolling clamp, and then transmits the radial load to the fixed frame 8 (frame) through the meshing of its left planetary gear 12 and right planetary gear 22 with the left internal gear ring 11 and right internal gear ring 21, respectively. The free-floating center support ring 51 balances the load between the left and right planetary gear sets, rather than transmitting it to the fixed structure. Therefore, no dedicated output bearing is required between the output component 7 and the fixed structure.

[0052] In this embodiment, the output component 7 and the frame 8 are kinematically coupled through a planetary gear reducer 10 and can rotate relative to each other within a set angle range.

[0053] In this embodiment, to further improve rigidity, the following structure is also provided (see [link to previous embodiment]). Figure 4 The second connecting shaft 32 extends to both ends, exceeding the outer end faces of the left planetary gear 12 of the left planetary gear set and the right planetary gear 22 of the right planetary gear set, respectively. A left outer support ring 61 is installed on the extended shaft exceeding the outer end face of the left planetary gear 12 of the left planetary gear set. The left outer support ring 61 abuts against the inner diameter surface of the left outer rolling ring 54-1, which is coaxially arranged with the left internal gear ring 11 of the left planetary gear set. A right outer support ring 62 is installed on the extended shaft exceeding the outer end face of the right planetary gear 22 of the right planetary gear set. The right outer support ring 62 abuts against the inner diameter surface of the right outer rolling ring 54-2, which is coaxially arranged with the right internal gear ring 21 of the right planetary gear set. With a suitable design, the left outer rolling ring 54-1 and the left outer support ring 61 are in a rolling fit, and the right outer rolling ring 54-2 and the right outer support ring 62 are also in a rolling fit.

[0054] Specifically, taking the left-side assembly as an example, each left planetary gear 12 end is provided with a left outer support ring 61. The left outer support ring 61 is located on the second connecting shaft 32, at the pitch circle of the left planetary gear 12, and rolls without slippage on the left outer rolling ring 54-1 of the frame 8, which is fixed and does not rotate at the pitch circle of the left internal gear ring 11. Therefore, the left outer rolling rings 54-1 of the two frames 8, located at two axially spaced end positions, directly transmit the net radial load and overturning moment to the corresponding first arm 81 and second arm 82 through pure rolling. The overturning moment has the same large lever arm as mentioned above, so as to improve the radial and moment bearing capacity and stiffness of the bearingless output.

[0055] In this embodiment, as Figure 4 As shown, the output component 7 is supported between two axially spaced first arms 81 and second arms 82 of the U-shaped frame 8—bearing the entire combined load range at the output through three different, synergistic reaction paths, namely axial thrust, radial load and overturning moment.

[0056] Specifically, axial thrust: Axial thrust originates from the axial side of the output component 7, and is transmitted to the first arm 81 and the second arm 82 via a thrust washer 50 made of a low-friction polymer (such as PEEK or polyoxymethylene) disposed between the side of the output component 7 and the wall. Radial load: As described, radial load is transmitted to the planetary gear set via the planetary support ring 52 and the rolling ring 53, the central support ring 51 and the planetary support ring 52, and is transmitted to the fixed frame 8 via the meshing of the left (right) planetary gear and the left (right) internal gear ring. Overturning moment: The overturning moment acting on the output component 7 is manifested as equal and opposite radial forces at two axially spaced support positions. Each radial force is transmitted via the meshing of adjacent left (right) planetary gears and left (right) internal gear rings to the left (right) internal gear rings supported by the first arm 81 and the second arm 82 of the frame 8. Thus, the two left (right) internal gear rings react in opposite directions, forming a reaction couple with a lever arm equal to the axial distance between the first arm 81 and the second arm 82. This large lever arm provides the output with high anti-overturning stiffness and moment carrying capacity. The contact between the thrust washers 50 and the central support rings 51 and planetary support rings 52 at the two locations further enhances the anti-tilting capability. In one example, at least one end face of the thrust washers 50 is also provided with a non-contact sealing structure 51 facing the output component 7, thereby avoiding the continuous output resistance exerted by a contact lip seal. Since all three load directions (axial, radial, and overturning) are borne by rolling bearings and frame 8, output component 7 does not require any type of special bearing.

[0057] In view of this, this application provides a planetary gear reducer 10, including a left planetary gear set and a right planetary gear set arranged in corresponding positions, an intermediate planetary gear set located between the left and right planetary gear sets, and a support ring group composed of multiple support rings. The left internal gear ring 11 of the left planetary gear set and the right internal gear ring 21 of the right planetary gear set are opposite each other and fixed to the first arm 81 and the second arm 82 of the frame, respectively. The shafts of the left sun gear 13 of the left planetary gear set and the right sun gear 23 of the right planetary gear set are connected by a first connecting shaft 31, and the shafts of the left planet gear 12 of the left planetary gear set and the right planet gear 22 of the right planetary gear set are connected by a second connecting shaft 32. The intermediate planetary gear set includes an intermediate internal gear ring 41 and intermediate planet gears 42, wherein the intermediate planet gears 42 of the intermediate planetary gear set are fixedly mounted on the second connecting shaft 32, and the intermediate internal gear ring 41 of the intermediate planetary gear set is fixedly mounted on the output component 7. The support ring assembly includes a central support ring 51 mounted via a first connecting shaft 31 and a planetary support ring 52 mounted via a second connecting shaft 32. The outer diameter surface of the central support ring 51 abuts against the outer diameter surface of the planetary support ring 52, and the outer diameter surface of the planetary support ring 52 also abuts against the inner diameter surface of the rolling ring 53 coaxially arranged with the intermediate internal gear ring 41, thereby achieving rotational support for the intermediate internal gear ring 41 of the intermediate planetary gear set relative to the first connecting shaft 31.

[0058] It can be understood that the planetary gear reducer 10 provided in this application achieves balance through the symmetrical arrangement of the left and right planetary gear sets and their meshing with the central planetary gear set, so that the planetary gears in the left and right planetary gear sets can be aligned without the need for a planet carrier, while the central support ring positions the planetary gears from the inside. The output component 7 is supported on the planetary gear set through the non-slip rolling contact between the support surface of its rolling ring 53 and the support surface of each planetary gear, thus eliminating the need for a dedicated output bearing. Moreover, the planetary gear reducer 10 is mounted between the first arm 81 and the second arm 82 of the frame 8 to obtain rigidity and is integrated into a transmission component with high torque density, compactness, reliability, and low cost.

[0059] Second Embodiment This application also provides a rotary joint 20 for a robot, the rotary joint 20 including a base part and a movable part that can rotate relative to each other within a set angle range, and a planetary gear reducer 10 that can connect the base part and the movable part using the first embodiment described above; wherein, the frame is disposed on the base part, the intermediate planetary gear set is fixed to the movable part by its internal gear ring; the drive motor is mounted on the outside of the sun gear of the left planetary gear set or the right planetary gear set, and its output shaft is connected to the sun gear shaft.

[0060] Specifically, in one example, the frame 8 has a first arm 81 and a second arm 82. The output component 7 is positioned between the first arm 81 and the second arm 82 and supported on both axial sides, avoiding the problems associated with cantilever designs. A left internal gear ring 11 and a right internal gear ring 21 are housed in the frame 8. The left and right internal gear rings 11 and 21 are respectively installed in the mounting holes 83 of the corresponding first arm 81 and second arm 82, and receive an integrated input arm 30 for connecting the robot's first link. The output arm 40, integrated with the output component 7, forms the robot's second link. Thus, the rotary joint 20 forms a rotational joint between the two links, with the frame 8 as one link and the output component 7 as the other, thereby eliminating the need for separate input and output adapters and shortening the joint length.

[0061] Third Embodiment This application also provides a robot, wherein the rotary joint 20 of the robot can refer to the rotary joint 20 for a robot described in the second embodiment above.

[0062] It should be noted that although several structures, components, or units for implementing the relevant functions have been mentioned in the detailed description above, this division is not mandatory. In fact, according to the specific embodiments of this application, the features and functions of two or more structures, components, or units described above can be embodied in one structure, component, or unit. Conversely, the features and functions of one structure, component, or unit described above can be further divided and embodied by multiple components, structures, or units.

[0063] Furthermore, although the various components of the components or apparatus in this application and the mounting arrangements between them are described in a specific order in the accompanying drawings, this does not require or imply that the components or apparatus must be designed according to that specific component or mounting arrangement, or that all the components shown must be included to achieve the desired result. Additional or alternative components may be omitted, multiple components may be combined into one component to achieve the corresponding function, and / or a component may be decomposed into multiple components to achieve the corresponding function, etc.

[0064] Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of this application. Therefore, the scope of protection of this application should be determined by the scope defined in the claims of this application.

Claims

1. A planetary gear reducer, characterized in that, It includes a left planetary gear set and a right planetary gear set arranged in corresponding relative positions, an intermediate planetary gear set located between the left planetary gear set and the right planetary gear set, and a support ring set composed of multiple support rings; The left internal gear ring of the left planetary gear set and the right internal gear ring of the right planetary gear set are opposite to each other and fixed to the first arm and the second arm opposite to each other on the first frame. The axis of the left sun gear of the left planetary gear set and the axis of the right sun gear of the right planetary gear set are connected by a first connecting shaft. The axis of the left planet gear of the left planetary gear set and the axis of the right planet gear of the right planetary gear set are connected by a second connecting shaft. The intermediate planetary gear set includes an intermediate internal gear ring and intermediate planetary gears, wherein the intermediate planetary gears of the intermediate planetary gear set are fixedly mounted on the second connecting shaft; the intermediate internal gear ring of the intermediate planetary gear set is fixedly mounted on the output component; The support ring assembly includes a central support ring sleeved on the first connecting shaft and a planetary support ring mounted via the second connecting shaft; wherein, the outer diameter surface of the central support ring abuts against the outer diameter surface of the planetary support ring, and the outer diameter surface of the planetary support ring also abuts against the inner diameter surface of the rolling ring coaxially arranged with the intermediate internal gear ring, thereby realizing rotational support for the intermediate internal gear ring of the intermediate planetary gear assembly relative to the first connecting shaft.

2. The planetary gear reducer according to claim 1, characterized in that, The support ring group includes a first support ring group and a second support ring group arranged on the left and right sides of the intermediate planetary gear set.

3. The planetary gear reducer according to claim 1 or 2, characterized in that, The outer diameter surface of the planetary support ring is located on the cylindrical surface formed by the vertical projection of the pitch circle of the coaxially arranged intermediate planetary gear; the inner diameter surface of the rolling ring coaxially arranged in the intermediate internal gear ring is located on the cylindrical surface formed by the vertical projection of the pitch circle of the intermediate internal gear ring.

4. The planetary gear reducer according to claim 1, characterized in that, The left planetary gear of the left planetary gear set and the right planetary gear of the right planetary gear set are respectively arranged symmetrically with the first connecting shaft as the center, with two or more of them.

5. The planetary gear reducer according to claim 1, characterized in that, The left planetary gear of the left planetary gear set and the right planetary gear of the right planetary gear set have the same number of teeth and module.

6. The planetary gear reducer according to claim 1, characterized in that, The output component is connected to the second frame, and the second frame and the first frame are kinematically coupled through the planetary gear reducer, and can rotate relative to each other within a set angle range.

7. The planetary gear reducer according to claim 1, characterized in that, The second connecting shaft extends axially at both ends and exceeds the outer end faces of the left planetary gear of the left planetary gear set and the right planetary gear of the right planetary gear set, respectively. A left outer support ring is installed on the extended shaft that exceeds the outer end face of the left planetary gear of the left planetary gear set. The left outer support ring abuts and rolls with the inner diameter surface of the left outer rolling ring that is coaxially arranged with the left internal gear ring of the left planetary gear set. A right outer support ring is installed on the extended shaft that exceeds the outer end face of the right planetary gear of the right planetary gear set. The right outer support ring abuts and rolls with the inner diameter surface of the right outer rolling ring that is coaxially arranged with the right internal gear ring of the right planetary gear set.

8. A rotary joint for a robot, characterized in that, The rotary joint includes a base and a movable part that are rotatable relative to each other within a set angle range, and a planetary gear reducer that connects the base and the movable part using any one of claims 1-7; wherein, a first frame is disposed on the base, and the intermediate planetary gear set is fixed to the movable part by its internal gear ring; a drive motor is mounted on the outside of the sun gear of the left or right planetary gear set, and its output shaft is connected to the sun gear shaft.

9. A robot, characterized in that, The robot's rotary joint is the rotary joint for robots as described in claim 8.

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