Reverse planetary roller screw suitable for humanoid robot

Abstract

The invention provides a reverse planetary roller screw suitable for a humanoid robot, and relates to the technical field of planetary roller screws. One end of each short nut is provided with an internal thread, the other end of each short nut is provided with an external thread, and the middle of each short nut is provided with a multi-head internal thread with a slightly small diameter. A plurality of short nuts are mutually connected through the internal threads and the external threads at the two ends to form a combined long nut with a large length-diameter ratio. The combined long nut, a lead screw with multiple external threads and a plurality of rollers jointly form the reverse planetary roller lead screw suitable for the humanoid robot. According to the reverse planetary roller screw nut, the machining problem of a traditional single large-length-diameter-ratio nut of a reverse planetary roller screw is solved, only a plurality of short nuts need to be machined, the machining difficulty is greatly reduced, the manufacturing cost is reduced, and the production efficiency is improved. In addition, the connection mode of the combined long nut is more efficient and simpler, and the combined long nut is more suitable for being combined with a frameless torque motor to form a humanoid robot linear joint module.

Description

Technical Field

[0001] This invention relates to the field of mechanical transmission technology, specifically to a planetary roller screw, and more particularly to a reverse planetary roller screw suitable for high-load, high-precision linear motion scenarios, especially suitable for humanoid robot linear joint modules. Background Technology

[0002] Planetary roller screws are precision transmission components that convert rotary motion into linear motion. Compared to ball screws, they offer higher load-bearing capacity, rigidity, and accuracy. Reverse-type planetary roller screws are an important form, characterized by a nut as the driving element that rotates, with the linear output from the screw. There is no relative axial displacement between the rollers and the screw, and the screw's stroke is determined by the length of the nut.

[0003] Traditional reverse planetary roller screws have the following technical bottlenecks: High machining difficulty: When large-stroke transmission is required, the nut must have a large length-to-diameter ratio. The inside of this slender nut needs to be machined with complex multi-start internal threads. Deep hole machining is prone to deformation, which leads to the accumulation of pitch error. Moreover, heat treatment is extremely difficult, resulting in a low yield.

[0004] Assembly and maintenance difficulties: Once the internal threads of a one-piece long nut are damaged, the entire nut often needs to be scrapped, as it cannot be repaired or replaced in sections.

[0005] Low structural integration: Traditional structures are relatively bulky and difficult to integrate compactly with frameless torque motors commonly used in humanoid robot joints, resulting in large joint modules with slow response speed.

[0006] Therefore, developing a reverse planetary roller screw that can reduce processing difficulty, facilitate modular assembly, and is suitable for integration with direct drive motors is an urgent need in the fields of humanoid robots and precision automation. Summary of the Invention

[0007] The purpose of this invention is to provide a reverse planetary roller screw suitable for humanoid robots. By using modular short nut splicing technology, the problem of difficult processing of nuts with large length-to-diameter ratios is solved. At the same time, the overall structure is optimized, making it more suitable for integration with frameless torque motors and application in the linear joints of humanoid robots.

[0008] The objective of this invention is achieved through the following technical solution: This invention provides a reverse planetary roller screw suitable for humanoid robots, comprising a combined long nut, screw, rollers, cage, etc.

[0009] The combined long nut is composed of several short nuts with the same structure connected end to end by threads.

[0010] The short nut has an external thread at one end and an internal thread at the other end, and the main body in the middle has a multi-threaded internal thread.

[0011] The thread diameter of the middle main body of the short nut is slightly smaller than the diameter of the external and internal threads at both ends.

[0012] Furthermore, two adjacent short nuts are connected by screwing the internal thread at one end to the external thread at the other end, thereby forming a combined long nut with the required length.

[0013] The lead screw is a hollow or solid rod-shaped structure. One end of its outer circumference is machined with an external thread that has the same pitch and number of threads as the main body of the short nut. The thread length is the same as the roller thread length, and the helix angle is equal to that of the roller thread. External straight teeth are machined at both ends of the lead screw thread.

[0014] The rollers are provided in several parts and are evenly distributed in the gap between the lead screw and the combined long nut. The outer circumferential surface of the roller is machined with a single-start thread that meshes with the thread of the lead screw and the thread of the combined long nut. Straight teeth are machined at both ends of the roller thread and mesh with the straight teeth of the lead screw. The two ends of the roller are cylindrical shafts with a diameter smaller than the roller thread, which fit with the small holes on the outer circumference of the cage.

[0015] The cage is used to keep the rollers evenly distributed in the circumferential direction and guide the rollers to perform planetary motion; the large hole in the middle of the cage cooperates with the lead screw, and two cages are installed on the lead screw shaft, which are positioned on the lead screw shaft by spring retaining rings.

[0016] Furthermore, multiple rollers are evenly distributed between two cages, and the cages limit and maintain the relative position of the rollers and the lead screw to prevent axial movement.

[0017] Furthermore, the thread direction of the lead screw is the same as that of the combined long nut, and opposite to that of the roller.

[0018] Furthermore, the external thread of the roller engages with the internal thread of the combined long nut and with the external thread of the lead screw; when the combined long nut rotates, the roller performs planetary motion along the circumference within the combined long nut under the combined constraint of the internal thread of the combined long nut and the external thread of the lead screw; the rotational motion of the combined long nut is converted into the linear motion of the lead screw through the planetary motion of the roller.

[0019] Furthermore, the combined long nut can be composed of several short nuts of the same length, or it can be composed of several short nuts of different lengths.

[0020] Compared with the prior art, the present invention has the following significant advantages: Significantly reduces machining difficulty: The difficult-to-machine long nuts with a large length-to-diameter ratio are broken down into multiple short nuts for machining. The short nuts have a smaller length-to-diameter ratio, making hole drilling and thread grinding easier and ensuring accuracy. Heat treatment deformation is also minimal, greatly improving production efficiency and yield.

[0021] Modular design and maintainability: The modular long nut is assembled from standard short nuts, and the number of short nuts can be increased or decreased as needed to adjust the stroke. If a section of the thread wears out, only the corresponding short nut needs to be replaced, without scrapping the entire transmission mechanism.

[0022] Efficient and simple connection: The short nuts are connected by direct thread engagement, without the need for additional flanges, keys or welding processes, resulting in fast assembly speed and good coaxiality.

[0023] Suitable for robot joints: This compact structure of short nuts spliced ​​together to form a combined long nut is easy to combine with frameless motors to form a linear joint module for humanoid robots, which is very suitable for the requirements of humanoid robot joints for lightweight and high integration. Attached Figure Description

[0024] Figure 1 This invention provides a cross-sectional schematic diagram of the overall structure of a reverse planetary roller screw suitable for humanoid robots.

[0025] Figure 2 : A magnified schematic diagram of the overall structure of a single short nut.

[0026] Figure 3 Enlarged cross-sectional view of a single short nut.

[0027] Figure 4 : Schematic diagram of the overall structure of the combined long nut.

[0028] Figure 5 A partially enlarged schematic diagram of the meshing of the roller, lead screw, and combined long nut.

[0029] In the attached diagram, 1 represents a short nut, 2 represents a combined long nut, 3 represents a lead screw, 4 represents a roller, and 5 represents a cage. Detailed Implementation

[0030] The preferred embodiments of the present invention will now be described with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0031] like Figure 1-5 As shown, the reverse planetary roller screw applicable to humanoid robots involved in this embodiment includes: Composite long nut: It is formed by connecting several short nuts with the same structure end to end by threads; one end of each short nut has an external thread, the other end has an internal thread, and the middle main body has multiple internal threads; the thread diameter of the middle main body of the short nut is slightly smaller than the diameter of the external and internal threads at both ends; two adjacent short nuts are connected by screwing the internal thread at one end to the external thread at the other end, thereby forming a composite long nut with the required length.

[0032] Lead screw: It is a hollow or solid rod-shaped structure. One end of its outer circumference is machined with an external thread with the same pitch and number of threads as the main body of the short nut. The thread length is the same as the roller thread length, and the helix angle is equal to that of the roller thread. External straight teeth are machined at both ends of the lead screw thread.

[0033] Rollers: Several rollers are provided, evenly distributed in the gap between the lead screw and the combined long nut; the outer circumference of the roller is machined with a single-start thread that meshes with the thread of the lead screw and the thread of the combined long nut; straight teeth are machined at both ends of the roller thread, which mesh with the straight teeth of the lead screw; the two ends of the roller are cylindrical shafts with a diameter smaller than the roller thread, which fit with the small holes on the outer circumference of the cage.

[0034] Cage: Used to keep the rollers evenly distributed in the circumferential direction and guide the rollers in planetary motion; the large hole in the middle of the cage cooperates with the lead screw, and is positioned on the lead screw shaft by a spring retainer. Two cages are installed on the lead screw shaft; multiple rollers are evenly distributed between the two cages, and the cages limit and maintain the relative position of the rollers and the lead screw to prevent axial movement.

[0035] This embodiment relates to a reverse planetary roller screw suitable for humanoid robots, wherein the screw thread direction is the same as that of the combined long nut and opposite to that of the roller.

[0036] This embodiment relates to a reverse planetary roller screw suitable for humanoid robots. The external thread of the roller meshes with the internal thread of the combined long nut and with the external thread of the screw. When the combined long nut rotates, the roller performs planetary motion along the circumference within the combined long nut under the combined constraint of the internal thread of the combined long nut and the external thread of the screw. The rotational motion of the combined long nut is converted into the linear motion of the screw through the planetary motion of the roller.

[0037] This embodiment relates to a reverse planetary roller screw suitable for humanoid robots. The combined long nut can be composed of several short nuts of the same length or several short nuts of different lengths.

[0038] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. However, any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope of the claims.

Claims

1. A reverse-type planetary roller screw suitable for humanoid robots, characterized in that, Includes a combination long nut (2), lead screw (3), roller (4), and cage (5); The combined long nut (2) is formed by connecting several short nuts (1) with the same structure end to end by thread; The short nut (1) has an external thread at one end and an internal thread at the other end, and the main body in the middle has a multi-threaded internal thread. The thread diameter of the middle main body of the short nut (1) is slightly smaller than the diameter of the external and internal threads at both ends; Two adjacent short nuts (1) are connected by the internal thread at one end and the external thread at the other end, thereby forming a combined long nut (2) with the required length. The combined long nut (2) can be composed of several short nuts (1) of the same length, or it can be composed of several short nuts (1) of different lengths.

2. The reverse planetary roller screw suitable for humanoid robots according to claim 1, characterized in that, The lead screw (3) is a hollow or solid rod-shaped structure. On the outer circumference of one end, there is an external thread with the same pitch and number of threads as the main body of the short nut (1). The thread length is the same as the thread length of the roller (4), and the helix angle is equal to that of the roller (4). External straight teeth are machined at both ends of the thread of the lead screw (3).

3. The reverse planetary roller screw suitable for humanoid robots according to claim 1, characterized in that, The rollers (4) are provided in several parts and are evenly distributed in the gap between the lead screw (3) and the combined long nut (2); the outer circumferential surface of the rollers (4) is machined with single-start threads that mesh with the threads of the lead screw (3) and the combined long nut (2); straight teeth are machined at both ends of the roller (4) threads and mesh with the straight teeth of the lead screw (3); the two ends of the rollers (4) are cylindrical shafts with a diameter smaller than the roller (4) threads and fit with the small holes on the outer circumference of the cage (5).

4. A reverse planetary roller screw suitable for humanoid robots according to claim 1, characterized in that, The cage (5) is used to keep each roller (4) evenly distributed in the circumferential direction and guide the roller (4) to perform planetary motion; the large hole in the middle of the cage (5) cooperates with the lead screw (3), and two cages (5) are installed on the lead screw (3) shaft, which are positioned on the lead screw (3) shaft by spring retainers.

5. A reverse planetary roller screw suitable for humanoid robots according to any one of claims 3 to 4, characterized in that, Multiple rollers (4) are evenly distributed between two cages (5). The cages (5) limit and maintain the relative position of the rollers (4) and the lead screw (3) to prevent axial movement.

6. A reverse planetary roller screw suitable for humanoid robots according to any one of claims 1 to 3, characterized in that, The thread direction of the lead screw (3) is the same as that of the combined long nut (2) and opposite to that of the roller (4).

7. A reverse planetary roller screw suitable for humanoid robots according to any one of claims 1 to 3, characterized in that, The external thread of the roller (4) meshes with the internal thread of the combined long nut (2) and with the external thread of the lead screw (3). When the combined long nut (2) rotates, the roller (4) performs planetary motion in the circumferential direction within the combined long nut (2) under the combined constraint of the internal thread of the combined long nut (2) and the external thread of the lead screw (3). The rotational motion of the combined long nut (2) is converted into the linear motion of the lead screw (3) through the planetary motion of the roller (4).

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