Joint actuator and two-stage planetary reducer thereof

Abstract

The two-stage planetary reducer comprises a first-stage sun gear and a second-stage sun gear which are coaxially arranged, the first-stage sun gear and the second-stage sun gear are sleeved with a long gear ring, and the long gear ring extends to the second-stage sun gear from the first-stage sun gear in the axial direction. A first-stage planet wheel and a first-stage planet carrier for mounting the first-stage planet wheel are arranged between the long gear ring and the first-stage sun wheel; a second-stage planet wheel and a second-stage planet carrier for mounting the second-stage planet wheel are arranged between the long gear ring and the second-stage sun wheel; long inner teeth are arranged on the inner wall of the long gear ring, the first-stage planet wheel is meshed with the first-stage sun wheel and the long inner teeth, and the second-stage planet wheel is meshed with the second-stage sun wheel and the long inner teeth. The long gear ring is fixedly arranged, and the first-stage planet carrier is in transmission connection with the second-stage sun gear. The utility model further discloses a joint actuator. According to the joint actuator and the two-stage planetary reducer thereof, the requirement for a large transmission ratio can be met, and the size cannot be increased.

Description

Technical Field

[0001] This invention belongs to the field of robotics technology, specifically a joint actuator and its two-stage planetary reducer. Background Technology

[0002] As the core power component of a robot system, the joint actuator plays a crucial role in converting electrical energy into mechanical motion. Its performance directly affects the robot's motion accuracy, load capacity, response speed, and overall reliability. Technically, a typical joint actuator usually consists of modules such as a drive motor, reduction gear, sensor system, and control unit. These components are precisely integrated to achieve functions such as torque amplification, motion conversion, and closed-loop control. With the continuous expansion of robot applications, from industrial manufacturing to medical services, from space exploration to home services, the performance requirements for joint actuators are becoming increasingly diversified and stringent.

[0003] Mechanically reduced-speed articulated actuators have long dominated the field of industrial robots. Their core technology utilizes gear meshing to reduce the motor's output speed and amplify its torque. These actuators typically employ a three-stage architecture: the high-speed stage provides the initial power to the servo motor; the intermediate stage uses a precision reducer to achieve speed and torque variation; and the output stage integrates position / torque sensors to form a closed-loop control. Based on the type of reduction mechanism, mainstream solutions can be divided into three main categories: harmonic reducers, planetary reducers, and RV reducers, each with distinct performance characteristics and applicable scenarios. Among them, planetary reducers employ a multi-stage parallel gear splitting structure, offering advantages in high rigidity and high load capacity, and are commonly found in heavy-duty industrial robots. However, achieving a large transmission ratio with existing planetary reducers leads to an increase in radial dimensions, limiting their application in space-constrained environments. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a joint actuator and its two-stage planetary reducer, which can not only achieve the requirement of a large transmission ratio, but also without increasing the size.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This utility model first proposes a two-stage planetary reducer for a joint actuator, including a first-stage sun gear and a second-stage sun gear arranged coaxially. The first-stage sun gear and the second-stage sun gear are fitted with a long gear ring, which extends axially from the second-stage sun gear to the first-stage sun gear. A first-stage planet gear and a first-stage planet carrier for mounting the first-stage planet gear are provided between the long gear ring and the first-stage sun gear. A second-stage planet gear and a second-stage planet carrier for mounting the second-stage planet gear are provided between the long gear ring and the second-stage sun gear.

[0007] The inner wall of the long gear ring is provided with long internal teeth. The first-stage planetary gear meshes with the first-stage sun gear and the long internal teeth respectively. The second-stage planetary gear meshes with the second-stage sun gear and the long internal teeth respectively.

[0008] The long gear ring is fixedly installed, and the first-stage planetary carrier is connected to the second-stage sun gear via a transmission.

[0009] Furthermore, the number of teeth on the first-stage planetary gear and the second-stage planetary gear may be equal or unequal.

[0010] Furthermore, the number of teeth on the first-stage sun gear and the second-stage sun gear may be equal or unequal.

[0011] Furthermore, the primary planetary carrier is disposed between the primary planetary gears and the secondary planetary gears, and the primary planetary carrier rotates synchronously with the secondary sun gear.

[0012] Furthermore, the axis of rotation of the first-stage planetary carrier and the second-stage sun gear are integrated.

[0013] This utility model also proposes a joint actuator, including a housing, a motor assembly inside the housing, the motor assembly including a stator and a rotor sleeved outside the stator, a central through hole in the stator, a two-stage planetary reducer as described above installed in the central through hole; a long gear ring sleeved in the central through hole and fixedly connected to the housing, a first-stage sun gear drivingly connected to the rotor, and an output flange on the second-stage planetary carrier.

[0014] Furthermore, the housing includes a shell and an end cap mounted on the shell.

[0015] Furthermore, a connecting disc is connected to the rotor, and the connecting disc is located between the housing and the stator; the center of the connecting disc is provided with an axially extending connecting portion, and a connecting through hole is provided in the connecting portion, and the shaft of the first-stage sun gear is installed in the connecting through hole.

[0016] Furthermore, the housing is provided with a clearance hole to accommodate the connecting part, and the inner diameter of the long gear ring is larger than the outer diameter of the connecting part; deep groove ball bearings are respectively provided between the connecting part and the housing and the long gear ring.

[0017] Furthermore, the long toothed ring is fixedly connected to the end cap, and a crossed roller bearing is provided between the long toothed ring and the end cap and the secondary planetary carrier.

[0018] Furthermore, a magnetic bead is provided at the end of the central through hole facing away from the first-stage sun gear.

[0019] The beneficial effects of this invention are as follows:

[0020] This utility model's articulated actuator utilizes a two-stage planetary reducer. The rotor is connected to a first-stage sun gear, and the first-stage planetary carrier is connected to a second-stage sun gear. An output flange is mounted on the second-stage planetary carrier. Thus, first-stage reduction is achieved by the first-stage planetary gears meshing with both the long gear ring and the first-stage sun gear, and second-stage reduction is achieved by the second-stage planetary gears meshing with both the long gear ring and the second-stage sun gear. The total reduction ratio of the two-stage planetary reducers is the product of the first-stage and second-stage reduction ratios. This two-stage reduction achieves a larger transmission ratio while reducing the transmission ratios of both the first and second stages, thereby reducing the radial dimension of the planetary reducers. By placing the two-stage planetary reducers within the central through-hole of the stator and sharing a single long gear ring for both stages, the axial structure of the two-stage planetary reducers becomes more compact, resulting in a smaller axial dimension of the articulated actuator. In summary, this utility model's articulated actuator not only achieves a larger transmission ratio but also reduces the radial dimension without increasing the axial dimension. Attached Figure Description

[0021] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following figures are provided for illustration:

[0022] Figure 1 This is a schematic diagram of the structure of an embodiment of the joint actuator of this utility model;

[0023] Figure 2 for Figure 1 Left-axis projection;

[0024] Figure 3 for Figure 1 The right axonometric projection.

[0025] Explanation of reference numerals in the attached figures:

[0026] 10-Housing; 101-Protrusion; 102-Connecting hole; 11-End cover; 12-Stator; 13-Rotor; 14-First-stage sun gear; 15-Second-stage sun gear; 16-Long gear ring; 161-Long internal gear; 17-First-stage planetary gear; 18-First-stage planetary carrier; 19-Second-stage planetary gear; 20-Second-stage planetary carrier; 21-Output flange; 22-Connecting disc; 221-Connecting part; 222-Connecting through hole; 23-Deep groove ball bearing; 24-Deep groove ball bearing; 25-Crossed roller bearing; 26-Magnetic ball; 27-Circuit board. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0028] like Figure 1As shown, the joint actuator of this embodiment includes a housing, within which a motor assembly is housed. In this embodiment, the housing includes a shell 10 and an end cover 11, with the end cover 11 mounted on and fixedly connected to the shell 10. The motor assembly includes a stator 12 and a rotor 13 sleeved outside the stator 12. The stator 12 has a central through hole, within which a two-stage planetary reducer is installed. In this embodiment, the two-stage planetary reducer includes a first-stage sun gear 14 and a second-stage sun gear 15 coaxially arranged. A long gear ring 16 is sleeved on the first-stage sun gear 14 and the second-stage sun gear 15, extending axially from the second-stage sun gear 15 to the first-stage sun gear 14. A first-stage planetary gear 17 and a first-stage planet carrier 18 for mounting the first-stage planetary gear 17 are provided between the long gear ring 16 and the first-stage sun gear 14. A second-stage planetary gear 19 and a second-stage planet carrier 20 for mounting the second-stage planetary gear 19 are provided between the long gear ring 16 and the second-stage sun gear 15. Specifically, the inner wall of the long tooth ring 16 is provided with long internal teeth 161, the first-stage planetary gear 17 meshes with the first-stage sun gear 14 and the long internal teeth 161 respectively, and the second-stage planetary gear 19 meshes with the second-stage sun gear 15 and the long internal teeth 161 respectively.

[0029] In this embodiment, the long gear ring 16 is fixedly installed, and the primary planetary carrier 18 is connected to the secondary sun gear 15 via a transmission connection. Specifically, the primary planetary carrier 18 is positioned between the primary planetary gear 17 and the secondary planetary gear 19, and the primary planetary carrier 18 and the secondary sun gear 15 rotate synchronously. In a preferred embodiment, the shafts of the primary planetary carrier 18 and the secondary sun gear 19 are integrated, which simplifies the structure.

[0030] In this embodiment, the long gear ring 16 is fitted inside the central through hole and fixedly connected to the outer casing. The first-stage sun gear 14 is driven by the rotor 13, and the second-stage planetary carrier 20 is provided with an output flange 21. Specifically, a connecting disc 22 is connected to the rotor 13, and the connecting disc 22 is located between the housing 10 and the stator 12. The center of the connecting disc 22 is provided with an axially extending connecting portion 221, and a connecting through hole 222 is provided inside the connecting portion 221. The shaft of the first-stage sun gear 14 is installed in the connecting through hole 222. In this embodiment, the first-stage sun gear 14 rotates synchronously with the rotor 13 through the connecting disc 22. In this embodiment, a magnetic bead 26 is provided at the end of the connecting through hole 222 facing away from the first-stage sun gear 14.

[0031] In this embodiment, the housing 10 is provided with a clearance hole for the clearance connecting portion 221, and the inner diameter of the long gear ring 16 is larger than the outer diameter of the connecting portion 221. A deep groove ball bearing 23 and a deep groove ball bearing 24 are respectively provided between the connecting portion 221 and the housing 10 and the long gear ring 16.

[0032] In this embodiment, the long toothed ring 16 is fixedly connected to the end cap 11, and a cross roller bearing 25 is provided between the long toothed ring 16, the end cap 11 and the secondary planetary carrier 20.

[0033] Specifically, in this embodiment, the number of teeth on the first-stage planetary gear 17 and the second-stage planetary gear 19 are equal, and the number of teeth on the first-stage sun gear 14 and the second-stage sun gear 15 are equal. That is, in this embodiment, the transmission ratios of the first-stage reduction gear and the second-stage reduction gear are the same. Of course, in some other embodiments, the transmission ratios of the first-stage reduction gear and the second-stage reduction gear may not be the same. For example, the number of teeth on the first-stage planetary gear 17 and the second-stage planetary gear 19 may be unequal, or the number of teeth on the first-stage sun gear 14 and the second-stage sun gear 15 may be unequal, which will not be elaborated further.

[0034] In this embodiment, the end face of the housing 10 is provided with a protrusion 101, and the protrusion 101 is provided with connecting holes 102 at intervals. The protrusion 101 and the connecting holes 102 are used to mount the circuit board 27, etc., and will not be described in detail.

[0035] In this embodiment, the joint actuator uses a two-stage planetary reducer to drive the rotor 13 to the first-stage sun gear 14 and the first-stage planetary carrier 18 to the second-stage sun gear 15. An output flange 21 is provided on the second-stage planetary carrier 20. Thus, the first-stage planetary gear 17 meshes with the long gear ring 16 and the first-stage sun gear 14 to achieve first-stage reduction, and the second-stage planetary gear 19 meshes with the long gear ring 16 and the second-stage sun gear 15 to achieve second-stage reduction. The total reduction ratio of the two-stage planetary reducer is the product of the first-stage reduction ratio and the second-stage reduction ratio. That is, the two-stage reduction can meet the requirement of a large transmission ratio and can reduce the transmission ratio of the first-stage reduction and the second-stage reduction respectively, thereby reducing the radial dimension of the planetary reducer. By setting the two-stage planetary reducer in the central through hole of the stator 12 and making the first-stage reduction and the second-stage reduction share a long gear ring 16, the axial structure of the two-stage planetary reducer can be made more compact, and the axial dimension of the joint actuator can be smaller. In summary, the joint actuator of this embodiment can not only achieve the requirement of a large transmission ratio, but also reduce the radial dimension without increasing the axial dimension.

[0036] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A two-stage planetary reducer for a joint actuator, characterized in that: It includes a first-stage sun gear and a second-stage sun gear arranged coaxially. The first-stage sun gear and the second-stage sun gear are fitted with a long toothed ring. The long toothed ring extends axially from the second-stage sun gear to the first-stage sun gear. A first-stage planetary gear and a first-stage planet carrier for mounting the first-stage planetary gear are provided between the long toothed ring and the first-stage sun gear. A second-stage planetary gear and a second-stage planet carrier for mounting the second-stage planetary gear are provided between the long toothed ring and the second-stage sun gear. The inner wall of the long gear ring is provided with long internal teeth. The first-stage planetary gear meshes with the first-stage sun gear and the long internal teeth respectively. The second-stage planetary gear meshes with the second-stage sun gear and the long internal teeth respectively. The long gear ring is fixedly installed, and the first-stage planetary carrier is connected to the second-stage sun gear via a transmission.

2. The two-stage planetary reducer for the joint actuator according to claim 1, characterized in that: The number of teeth on the first-stage planetary gear and the second-stage planetary gear may be equal or unequal; the number of teeth on the first-stage sun gear and the second-stage sun gear may be equal or unequal.

3. The two-stage planetary reducer for the joint actuator according to claim 1, characterized in that: The primary planetary carrier is positioned between the primary planetary gears and the secondary planetary gears, and the primary planetary carrier rotates synchronously with the secondary sun gear.

4. The two-stage planetary reducer for the joint actuator according to claim 3, characterized in that: The primary planetary carrier and the secondary sun gear are integrated into one unit.

5. A joint actuator, characterized in that: The device includes a housing, within which a motor assembly is provided. The motor assembly includes a stator and a rotor fitted outside the stator. The stator has a central through hole, and a two-stage planetary reducer as described in any one of claims 1-4 is installed in the central through hole. A long gear ring is fitted inside the central through hole and fixedly connected to the housing. The first-stage sun gear is driven by the rotor. An output flange is provided on the second-stage planetary carrier.

6. The joint actuator according to claim 5, characterized in that: The outer casing includes a housing and end caps mounted on the housing.

7. The joint actuator according to claim 6, characterized in that: The rotor is connected to a connecting disc, which is located between the housing and the stator; the center of the connecting disc is provided with an axially extending connecting portion, and the connecting portion is provided with a connecting through hole, and the shaft of the first-stage sun gear is installed in the connecting through hole.

8. The joint actuator according to claim 7, characterized in that: The housing is provided with a clearance hole to accommodate the connecting part, and the inner diameter of the long gear ring is larger than the outer diameter of the connecting part; deep groove ball bearings are respectively provided between the connecting part and the housing and the long gear ring.

9. The joint actuator according to claim 6, characterized in that: The long gear ring is fixedly connected to the end cap, and a cross roller bearing is provided between the long gear ring and the end cap and the secondary planetary carrier.

10. The joint actuator according to claim 5, characterized in that: A magnetic bead is provided at the end of the central through hole facing away from the first-stage sun gear.

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