Deceleration structure, actuator, and robot

Abstract

This application relates to a reduction structure, actuator, and robot, applied in the field of robot drive devices. It includes an internal gear ring, planetary gears, and an output mechanism. The internal gear ring is fixed to a housing and includes a first shaft. The planetary gears mesh with the internal gear ring, and are capable of revolving around the first shaft and rotating around a second shaft, which is parallel to the first shaft. The planetary gears are capable of eccentric rotation relative to the internal gear ring. The output mechanism is driven by the planetary gears and rotates around the first shaft under their drive. There is a tooth difference between the number of teeth on the planetary gears and the number of teeth on the internal gear ring, and this tooth difference is greater than or equal to 1. This application utilizes an involute single-stage transmission structure with a small tooth difference, where the planetary gears mesh with the internal gear ring, to achieve a large transmission ratio in each stage. The meshing of the planetary gears with the inner ring of the internal gear ring does not increase the axial dimension of the reduction structure. The small tooth difference structure maximizes the pitch circle size of the planetary gears, thereby improving their load-bearing capacity.

Description

Technical Field

[0001] This application relates to the technical field of robot drive devices, and in particular to a deceleration structure, actuator, and robot. Background Technology

[0002] In the field of industrial and service robots, joint actuators, as the core components for power output, directly affect the robot's load capacity, motion accuracy, and energy consumption.

[0003] Power transmission in robot joint actuators largely relies on planetary reduction mechanisms. In related technologies, single-stage planetary reducers, due to structural limitations, have a maximum speed ratio of only 10-12, forcing the drive motor to operate in a low-speed range for extended periods, deviating from its efficient operating range, resulting in increased energy consumption and limited dynamic response. While a two-stage reduction scheme can increase the speed ratio to over 100 times, it significantly increases the axial length, severely impacting the compactness of the joint module.

[0004] In addition, the gear strength problem of existing single-stage reducers is also prominent: due to the limitation of the number of planetary gears and radial space, the module of the sun gear and planetary gears is forced to be reduced, which easily leads to an increased risk of fatigue failure. Utility Model Content

[0005] Therefore, it is necessary to provide a reduction structure, actuator, and robot to address the problem of how to simultaneously improve the reduction ratio and gear load-bearing capacity within a limited space.

[0006] Firstly, this application provides a deceleration structure, which adopts the following technical solution:

[0007] A speed reduction structure includes an internal gear ring, planetary gears, and an output mechanism. The internal gear ring is fixed to a housing and includes a first shaft. The planetary gears mesh with the internal gear ring and are configured to revolve around the first shaft and rotate around a second shaft parallel to the first shaft. The planetary gears are eccentrically rotated relative to the internal gear ring. The output mechanism is driven by the planetary gears and is capable of rotating around the first shaft under the drive of the planetary gears. The number of teeth on the planetary gears differs from the number of teeth on the internal gear ring by a difference greater than or equal to 1.

[0008] In one embodiment, the output mechanism includes a front planetary carrier and a drive pin. Along the first axis, the drive pin passes sequentially through the front planetary carrier and the planetary gear, such that the front planetary carrier is connected to the planetary gear by means of the drive pin. The planetary gear has a pin hole through which the drive pin passes, and the inner diameter of the pin hole is larger than the diameter of the drive pin.

[0009] In one embodiment, the output mechanism further includes a rear planetary carrier. Along the first axis, the front planetary carrier and the rear planetary carrier are respectively disposed on opposite sides of the planetary gear and connected to each other. The transmission pin passes through the front planetary carrier, the planetary gear and the rear planetary carrier in sequence.

[0010] In one embodiment, multiple pin holes are provided, and all of the pin holes are distributed at intervals along the circumference of the planetary gear.

[0011] In one embodiment, the difference in the number of teeth is any one of 1, 2, 3, or 4.

[0012] In one embodiment, two planetary gears are provided, and the two planetary gears are arranged side by side with the first axis as the axis.

[0013] Secondly, this application provides an actuator, which adopts the following technical solution:

[0014] An actuator includes the aforementioned reduction gear structure and a motor, the motor including a rotor, a stator and an output shaft, the rotor being configured to rotate under the drive of the stator, and the output shaft drivingly connecting the reduction gear structure to the rotor to drive the planetary gear to rotate eccentrically relative to the internal gear ring.

[0015] In one embodiment, the actuator further includes a swivel bearing, through which the output shaft is driven to the planetary gear. The swivel bearing includes an eccentric section extending radially along the internal gear ring, the length of which is equal to the distance between the first shaft and the second shaft.

[0016] In one embodiment, the motor is configured as an internal rotor motor; or, the motor is configured as an external rotor motor; the output shaft is coaxially connected to the rotor.

[0017] Thirdly, this application provides a robot that adopts the following technical solution:

[0018] A robot includes the actuator described above, the actuator serving as a joint of the robot.

[0019] The aforementioned reduction structure, employing an involute single-stage transmission with a small tooth difference and planetary gears meshing with an internal gear ring, achieves a large transmission ratio in each stage. Furthermore, the meshing of the planetary gears with the inner ring of the internal gear ring does not increase the axial dimensions of the reduction structure. Additionally, the small tooth difference structure maximizes the pitch circle size of the planetary gears, thereby enhancing their load-bearing capacity. Attached Figure Description

[0020] Figure 1This is an overall view of the actuator in one embodiment of this application.

[0021] Figure 2 for Figure 1 An overall view of the actuator from another perspective.

[0022] Figure 3 This is a cross-sectional view of an actuator in one embodiment of this application.

[0023] Figure 4 This is an exploded view of the actuator in one embodiment of this application.

[0024] Attached image annotations:

[0025] 1. Housing; 2. Internal gear ring; 3. Planetary gear; 31. Pin hole; 4. Output mechanism; 41. Front planetary carrier; 42. Rear planetary carrier; 43. Drive pin; 51. Rotor; 52. Stator; 53. Output shaft; 6. Swing arm bearing; 7. Pressure frame; 8. First bearing; 9. Second bearing; G1. First shaft; G2. Second shaft. Detailed Implementation

[0026] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough 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 modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0027] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms 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.

[0028] Furthermore, where the terms "first" and "second" appear, these terms are 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 with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0029] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0030] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0031] If an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0032] In the field of industrial and service robots, articulated actuators, as the core components for power output, directly affect the robot's load capacity, motion accuracy, and energy consumption. In related technologies, articulated actuators commonly employ a single-stage planetary gear reduction mechanism as the power transmission device. While this structure offers advantages such as compactness and high transmission efficiency, it suffers from the following key technical bottlenecks:

[0033] First, the theoretical transmission ratio of a single-stage planetary reducer is physically limited by the planetary gear train topology, with a maximum ratio of only 10-12 times in conventional designs. This ratio characteristic forces the drive motor to operate in a low-speed range (typically below 1000 rpm) for extended periods, causing the motor to deviate from its efficient operating range (the efficient range for conventional motors is mostly between 2000-4000 rpm), significantly reducing the system's energy efficiency ratio. Especially under conditions requiring frequent starts, stops, or reversals, the torque fluctuations caused by the motor's low-speed operation further exacerbate energy loss.

[0034] Secondly, to address the insufficient speed ratio issue, some improvement solutions have attempted to employ a two-stage planetary reduction gear series structure. While this design can increase the overall speed ratio to the range of 100-144 times, it leads to a cumulative increase in axial dimensions of approximately 1.8-2.2 times. Taking a typical collaborative robot wrist joint as an example, the axial length of the actuator will increase from the original 80mm level to over 150mm level, severely compromising the compactness of the joint module. This not only increases the rotational inertia of the robotic arm but also restricts the integrated design of multi-degree-of-freedom joints.

[0035] Furthermore, in existing single-stage reducer designs, the stress distribution on the tooth surfaces of the sun gear and planetary gears is affected by multiple spatial constraints: firstly, the number of planetary gears is limited by installation space and is usually no more than four, leading to uneven load distribution; secondly, due to the strict limitations of the outer diameter of the gear ring and the radial dimensions of the housing (conventional designs need to control it within Φ60mm), the module parameter is forced to be reduced to the 0.6-0.8mm range. Experimental data shows that under rated torque output conditions, the bending stress at the root of the sun gear tooth can reach over 800MPa, exceeding the allowable stress range of carburized and quenched gears, becoming the main failure mode of the transmission system.

[0036] The core challenge facing current technological development lies in how to overcome the speed ratio limitations of single-stage reduction while maintaining the axial dimension of the actuator without a significant increase, and simultaneously address the strength bottleneck of gear systems under high power density requirements. Therefore, there is an urgent need to develop a novel reduction mechanism design that achieves synergistic optimization of speed ratio improvement and structural strength within a limited space.

[0037] The following is in conjunction with the appendix Figure 1-4 The embodiments of this application will be described in further detail.

[0038] See Figure 1 , Figure 1 An overall view of the actuator in one embodiment of this application is shown. Figure 2 This application shows Figure 1 An overall view of the actuator from another perspective.

[0039] One embodiment of this application provides an actuator, including a housing 1 and a reduction gear structure and a motor disposed within the housing 1. The motor includes a rotor 51, a stator 52, and an output shaft 53. The stator 52 is fixed to the inner wall of the housing 1, and the rotor 51 can rotate under the drive of the stator 52. The output shaft 53 drives the reduction gear structure to the rotor 51, so that the motor can achieve reduced output through the reduction gear structure.

[0040] Combination Figure 3 As shown, Figure 3 A cross-sectional view of an actuator according to one embodiment of this application is shown. Figure 3 As shown in the example, in some embodiments, the motor is specifically an external rotor motor, with the rotor 51 located around the stator 52 and able to rotate around the first axis G1 under the drive of the stator 52.

[0041] It is understood that in some other embodiments, the motor may also be an internal rotor motor (not shown), with the rotor 51 located inside the stator 52 and able to rotate around the first shaft G1 under the drive of the stator 52, so as to drive the reduction structure connected to the output shaft 53 to output outward.

[0042] In this embodiment, the motor also includes a bearing sleeved around the output shaft 53, which is fixed between the output shaft 53 and the housing 1 to improve the operating stability of the actuator.

[0043] See Figure 3 and Figure 4 As shown, Figure 4 An exploded view of the actuator in one embodiment of this application is shown. Specifically, the reduction structure includes an internal gear ring 2, a planetary gear 3, and an output mechanism 4. The outer ring of the internal gear ring 2 is fixed to the inner wall of the housing 1 by a pressure frame 7, and the central axis of the internal gear ring 2 coincides with the first shaft G1. The planetary gear 3 is disposed in and meshes with the internal gear ring 2, and is configured to revolve around the first shaft G1 and rotate around the second shaft G2. The output mechanism 4 is driven by the planetary gear 3 and can rotate under the drive of the planetary gear 3 to achieve reduced output speed.

[0044] Furthermore, a first bearing 8 is provided between the outer ring of the front planetary carrier 41 and the inner wall of the housing 1, abutting against the front planetary carrier 41 and the housing 1 to fill the gap between them; a second bearing 9 is provided between the inner ring of the pressure frame 7 and the outer ring of the rear planetary carrier 42, abutting against the pressure frame 7 and the rear planetary carrier 42 to fill the gap between them. The arrangement of the first bearing 8 and the second bearing 9 can effectively improve the stability of the front planetary carrier 41 and the rear planetary carrier 42 during rotation.

[0045] In this embodiment of the application, for ease of explanation, the common central axis of the stator 52 and the rotor 51 is defined as the first axis G1. The central axis of the planetary gear 3 is defined as the second axis G2, which is parallel to the first axis G1. The planetary gear 3 is configured to rotate eccentrically relative to the internal gear ring 2, that is, the motion of the planetary gear 3 is a composite motion of rotation and revolution.

[0046] To achieve the eccentric rotation of the planetary gear 3, the actuator also includes a swivel bearing 6. The output shaft 53 of the motor is connected to the planetary gear 3 via the swivel bearing 6 to drive the planetary gear 3 to revolve. In this embodiment, the swivel bearing 6 includes an eccentric section (not shown) extending radially along the internal gear ring 2. The length of the eccentric section is equal to the distance between the first shaft G1 and the second shaft G2, that is, the length of the eccentric section is equal to the center distance between the planetary gear 3 and the internal gear ring 2.

[0047] Continue reading Figure 4 As shown in the embodiment of this application, the reduction structure adopts an involute single-stage transmission structure with a small tooth difference, in which the planetary gear 3 and the internal gear ring 2 cooperate. That is, there is a tooth difference between the number of teeth of the planetary gear 3 and the number of teeth of the internal gear ring 2, and the tooth difference is set to be greater than or equal to 1.

[0048] It is understandable that the basic principle of planetary gear transmission with small tooth difference is to achieve a high transmission ratio by reducing the difference in the number of teeth between the internal and external gears. In this application, the specific value of the tooth difference can be any one of 1, 2, 3, or 4. This application adopts an involute single-stage transmission with small tooth difference. Because the tooth difference is very small, the transmission ratio obtained in each stage is large, allowing each stage to achieve a large transmission ratio and adjust the motor's operating range. This solves the problems of insufficient motor output torque and low operating speed.

[0049] Planetary gear 3 meshes with the inner ring of internal gear ring 2. They overlap in the axial direction of the actuator, thus not increasing the axial size of the reduction structure. This effectively solves the problem of increased axial size in the two-stage reduction by using only one planetary gear 3. Furthermore, the low tooth difference structure maximizes the pitch circle size of planetary gear 3, thereby ensuring its load-bearing capacity and improving the strength of the reduction structure.

[0050] Combination Figure 3 and Figure 4As shown, the output mechanism 4 includes a front planetary carrier 41, a rear planetary carrier 42, and a transmission pin 43. Along the extension direction of the first shaft G1, the front planetary carrier 41 and the rear planetary carrier 42 are respectively positioned on opposite sides of the planetary gear 3. Along the extension direction of the first shaft G1, the transmission pin 43 sequentially passes through the front planetary carrier 41, the planetary gear 3, and the rear planetary carrier 42. The front planetary carrier 41 and the rear planetary carrier 42 can rotate around the first shaft G1 under the drive of the planetary gear 3 and the transmission pin 43 to achieve deceleration output. The front planetary carrier 41 and the rear planetary carrier 42 are fixedly connected by screws. Taking a single pin as an example, in the axial direction, two screws are respectively locked at both ends of the transmission pin 43 and respectively limit the axial displacement of the front planetary carrier 41 and the rear planetary carrier 42, thereby limiting the axial displacement of the front and rear planetary carriers.

[0051] Specifically, the planetary gear 3 has a pin hole 31 through which the transmission pin 43 passes. Along the extension direction of the first shaft G1, the transmission pin 43 passes through the planetary gear 3, and the inner diameter of the pin hole 31 is set to be larger than the diameter of the transmission pin 43, so as to avoid hindering the eccentric rotation of the planetary gear 3.

[0052] See Figure 2 As shown, in some other embodiments, multiple pin holes 31 are provided, and the multiple pin holes 31 are evenly distributed along the circumference of the planetary gear 3. Correspondingly, multiple transmission pins 43 are also provided, and they are arranged one-to-one with the pin holes 31. Each transmission pin 43 can participate in torque transmission to ensure the operational stability of the output mechanism 4.

[0053] In this embodiment, increasing the number of transmission pins 43 can distribute the torque borne by a single pin, thereby improving the system's load-bearing capacity and transmission efficiency. The number of transmission pins 43 is typically designed based on the size of the planetary gear 3 and its output torque requirements to ensure that it will not be damaged due to local overload during high torque transmission, effectively extending the actuator's service life.

[0054] In addition, the diameter of the transmission pin 43 needs to be designed according to the magnitude of the output torque. A larger diameter of the transmission pin 43 can withstand higher torque, but it will increase the weight and complexity of the planetary gear 3. The relationship between the diameter of the transmission pin 43 and the output torque can be calculated using material mechanics formulas to ensure that the transmission pin 43 is not prone to yielding or fatigue failure under maximum torque. The diameter of the transmission pin 43 usually needs to be determined through strength verification to ensure safety and reliability during high torque transmission.

[0055] In this embodiment, both the diameter and number of transmission pins 43 are positively correlated with the output torque. Increasing the number of transmission pins 43 can improve the uniformity of torque transmission and load-bearing capacity, while increasing the diameter of the transmission pins 43 can increase the load-bearing capacity of a single pin. During the design process, the size and number of transmission pins 43 need to be comprehensively considered based on the specific requirements of the output torque to achieve efficient and stable torque transmission.

[0056] Furthermore, to balance some inertial forces and improve load-bearing capacity, in some embodiments, each reduction structure includes two planetary gears 3, which are arranged side-by-side with the first shaft G1 as the axis. Correspondingly, the slewing arm bearing 6 is provided with two eccentric sections (not shown), which are connected one-to-one with the planetary gears 3, and the two eccentric sections are arranged at a 180° angle to each other.

[0057] In some embodiments, this application also provides a robot (not shown) including an actuator as shown in any of the above embodiments, a body (not shown), and legs (not shown), wherein the actuator is used to connect the legs to the body to act as a joint between the legs and the body, so that the legs can be pivotally connected to the body.

[0058] In this application embodiment, the robot includes, but is not limited to, semi-mobile robots (e.g., robotic arms, linear coordinate robots, cylindrical coordinate robots, articulated robots, etc.) and mobile robots (e.g., wheeled mobile robots, walking mobile robots, crawling robots, etc.).

[0059] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0060] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A deceleration structure characterized by, The deceleration structure includes: An internal gear ring, which can be fixed to the housing, includes a first shaft; A planetary gear meshes with the internal gear ring, the planetary gear being configured to revolve about a first axis and rotate about a second axis parallel to the first axis, the planetary gear being eccentrically rotated relative to the internal gear ring, and the planetary gear having a pin hole; and An output mechanism is driven to the planetary gear and can rotate around the first axis under the drive of the planetary gear; the output mechanism includes a front planetary carrier, a rear planetary carrier, and a transmission pin, the inner diameter of the pin hole being larger than the diameter of the transmission pin; along the first axis, the front planetary carrier and the rear planetary carrier are respectively disposed on opposite sides of the planetary gear and connected to each other, and the transmission pin sequentially passes through the front planetary carrier, the pin hole of the planetary gear, and the rear planetary carrier, so that the front planetary carrier is driven to the planetary gear by means of the transmission pin; There is a tooth difference between the number of teeth of the planetary gear and the number of teeth of the internal gear ring, and the tooth difference is greater than or equal to 1.

2. The speed reduction structure according to claim 1, characterized by, The pin holes are provided in multiple locations, and all the pin holes are distributed at intervals along the circumference of the planetary gear.

3. The speed reduction structure according to claim 1 or 2, characterized by, The difference in the number of teeth can be any one of 1, 2, 3, or 4.

4. The speed reduction structure according to claim 1, characterized by The planetary gears are provided in two pairs, which are arranged side by side with the first axis as the axis.

5. An actuator, characterized by The actuator includes: The deceleration structure as described in any one of claims 1-4; and An electric motor includes a rotor, a stator, and an output shaft. The rotor is configured to rotate under the drive of the stator, and the output shaft drives the reduction gear to the rotor to drive the planetary gear to rotate eccentrically relative to the internal gear ring.

6. The actuator of claim 5, wherein, The actuator also includes a swivel bearing, and the output shaft is connected to the planetary gear via the swivel bearing. The swivel bearing includes an eccentric section extending radially along the internal gear ring, and the length of the eccentric section is equal to the distance between the first shaft and the second shaft.

7. The actuator of claim 5, wherein, The motor is configured as an internal rotor motor; or, the motor is configured as an external rotor motor; the output shaft is coaxially connected to the rotor.

8. A robot, characterized in that Includes an actuator as described in any one of claims 5-7, the actuator serving as a joint of the robot.

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