A type of reverse planetary roller screw

Abstract

This application provides a reversible planetary roller screw, comprising an annular cage, multiple segmented rollers, an open cage, an integral screw, and a reverse nut. The annular cage includes a central through-hole and multiple cage through-holes evenly distributed along the circumference. The open cage includes an opening and multiple arc-shaped grooves evenly distributed along the outer edge of the circumference. The opening is used to open the cage so that it fits onto the integral screw. One end of each segmented roller is inserted into the cage through-hole with clearance fit, and the other end of each segmented roller is disposed in the arc-shaped groove with clearance fit. One end of the integral screw is disposed outside the end face of the reverse nut, which enables the integral screw to perform linear motion. This structure increases the strength and rigidity of the integral screw.

Description

Technical Field

[0001] This utility model relates to the field of roller screw technology, specifically to a reversible planetary roller screw with an integral screw. Background Technology

[0002] Lead screws are the most commonly used transmission components in machine tools and precision machinery. Their main function is to convert rotary motion into linear motion or torque into axial repetitive force, while also possessing the characteristics of high precision, reversibility, and high efficiency.

[0003] With the development of linear electric drive joints for humanoid robots, reversible planetary roller screws have gradually attracted attention from engineering and technology fields around the world due to their high precision, small size and large load-bearing capacity. Relevant studies have shown that using reversible planetary roller screws in humanoid robot joint actuators can significantly improve the system's operating accuracy and stability, while effectively avoiding problems such as large transmission backlash and rapid wear that exist in existing screw technologies.

[0004] Therefore, optimizing the design of reversible planetary roller screws to reduce manufacturing costs while ensuring high efficiency and long lifespan has become an important research direction for linear electric actuators with high thrust density and high force-to-weight ratio for humanoid robots. Utility Model Content

[0005] To address the aforementioned shortcomings, the purpose of this invention is to provide a high-precision, high-efficiency, integral ball screw with a reversible planetary roller screw, featuring a simple structure to solve the problems of existing technologies.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A reversible planetary roller screw includes an annular cage, multiple segmented rollers, an open cage, an integral screw, and a reversible nut. The annular cage includes a central through-hole and multiple cage through-holes evenly distributed along the circumference. The open cage includes an opening and multiple arc-shaped grooves evenly distributed along its outer circumference. The opening is used to open the cage so that it fits onto the integral screw. One end of each segmented roller is inserted into the cage through-hole with a clearance fit, and the other end is disposed in the arc-shaped groove with a clearance fit. One end of the integral screw, connected to the central through-hole, is disposed in the reversible nut, and the other end is disposed outside the end face of the reversible nut. The reversible nut is used to enable the integral screw to perform linear motion.

[0008] According to the embodiments of this application, the reversible planetary roller screw includes a first roller cylindrical portion, a first roller spur tooth portion, a roller threaded portion, a second roller cylindrical portion and a second roller spur tooth portion disposed in the arc-shaped groove. The surfaces of the first roller spur tooth portion and the second roller spur tooth portion are threaded, and the first roller spur tooth portion, the roller threaded portion and the second roller spur tooth portion mesh with the reversible nut.

[0009] According to the embodiments of this application, the reversible planetary roller screw includes a first cylindrical portion of the screw that passes through and connects to the central through hole, a first spur tooth portion of the screw that meshes with the first spur tooth portion of the roller, a threaded portion of the screw that meshes with the threaded portion of the roller, a second cylindrical portion of the screw disposed in the open cage, a second spur tooth portion of the screw that meshes with the second spur tooth portion of the roller, and a long cylindrical portion of the screw.

[0010] According to the embodiments of this application, the reversible planetary roller screw further includes a retaining ring with a snap ring. The cylindrical portion of the first screw has an annular groove, and the retaining ring with the snap ring is disposed in the annular groove for fixing and limiting the annular retainer.

[0011] According to the embodiments of this application, in the reversible planetary roller screw, the helix angle of the roller thread portion of the segmented roller and the screw thread portion of the integral screw is the same.

[0012] The design concept of this application is to design a reversible planetary roller screw structure. The integral screw is combined with an open cage, which is simple and reliable in structure and has stable product quality. It solves the problem that when the diameter of the screw is larger than the inner diameter of the cage, it cannot be placed into the lower cage and the screw needs to be assembled by separate processing. The roller screw structure of this application combines the external circulation control body and the transmission characteristics of planetary roller screw to realize the need to drive the linear motion of the integral screw through the rotation of the reverse nut.

[0013] Due to the adoption of the above technical features, this utility model has the following advantages and positive effects compared with the prior art:

[0014] First, the structure of this application increases the strength of the integral lead screw, resulting in better rigidity;

[0015] Secondly, the integral screw machining process of this application solves the problem of defects in the segmented machining and assembly process;

[0016] Third, the integral lead screw of this application is an integral structure, which can be hollow inside, allowing for lightweight design.

[0017] Of course, any specific embodiment of the present invention may not necessarily have all of the above technical effects at the same time. Attached Figure Description

[0018] Figure 1 This is a cross-sectional view of the roller screw portion of this application;

[0019] Figure 2 This is a schematic diagram of the annular cage of this application;

[0020] Figure 3 This is a schematic diagram of the open-type retainer of this application;

[0021] Figure 4 This is a schematic diagram of the segmented rollers in this application;

[0022] Figure 5 This is a schematic diagram of the integral lead screw of this application;

[0023] Figure 6 This is a schematic diagram of the reverse-type nut of this application;

[0024] Figure 7 This is a schematic diagram of the retaining ring spring of this application. Detailed Implementation

[0025] For ease of understanding, the preferred embodiments of this utility model will be described in further detail below with reference to the accompanying drawings.

[0026] Please refer to Figure 1 This application presents a cross-sectional schematic diagram of the ball screw portion, illustrating a reversible planetary ball screw structure. The integral ball screw, coupled with an open-type cage, offers a simple and reliable structure. By combining an external circulation control unit with the planetary ball screw transmission characteristics, it achieves the requirement of driving the integral ball screw linear motion via the rotation of a reverse-type nut. Furthermore, the open-type cage, made of PEEK material, provides oil-free lubrication, reducing friction and resonance during operation. It also offers advantages such as shock absorption, high-temperature resistance, corrosion resistance, and lightweight design, maintaining good physical properties and stability at high speeds.

[0027] like Figure 1 As shown, the roller screw described in this application includes a circular cage 2, multiple segmented rollers 3, an open cage 4, an integral screw 5, and a reverse nut 6. Please refer to... Figure 2 This application presents a schematic diagram of a circular retainer 2, which includes a central through-hole 21 and a plurality of retainer through-holes 22 evenly distributed along the circumferential direction; please refer to... Figure 3This application presents a schematic diagram of an open-type retainer. The open-type retainer 4 described in this application has an ingenious structure. The open-type retainer 4 includes an opening 41 and multiple arc-shaped grooves 42 evenly distributed along the outer edge of the circumference. The opening 41 is used to open so that the open-type retainer 4 fits into the integral lead screw 5. In this embodiment, the open-type retainer 4 is made of PEEK material, which allows the opening 41 to open and engage with the integral lead screw 5. The use of PEEK material gives the open-type retainer 4 oil-free lubrication, which can reduce friction and resonance during operation, and provides advantages such as shock absorption, high temperature resistance, corrosion resistance, and lightweight. It also maintains good physical properties and stability at high speeds. The groove width of the arc-shaped groove 42 is smaller than the inner diameter of the groove. The groove opening can open when a container enters and return to its original shape after the container enters, confining the container within the arc-shaped groove 42. In this embodiment of the application, the number of the plurality of segmented rollers 3, the plurality of cage through holes 22 and the plurality of arc grooves 42 are all eight, but this number cannot be used to limit this application. As long as the number of operations is met, they should all be within the scope of protection of this application.

[0028] Please refer to Figure 4 This application presents a schematic diagram of a segmented roller. One end of the segmented roller 3 is inserted into the cage through hole 22 with a clearance fit, allowing the segmented roller 3 to rotate within the cage through hole 22. The other end of the segmented roller 3 is disposed in the arc-shaped groove 42 with a clearance fit. During assembly, the column of the segmented roller 3 is pressed down from the opening of the arc-shaped groove 42, causing the opening to open. After the column of the segmented roller 3 enters the arc-shaped groove 42, the opened opening returns to its original position, and the arc-shaped groove 42... The segmented roller 3 is positioned within the groove 42 by a clearance fit with the column body. Because of the clearance fit, the segmented roller 3 can rotate within the arc-shaped groove 42. One end of the integral lead screw 5, which passes through the central through hole 21, is located in the reverse nut 6. The other end of the integral lead screw 5 is located outside the end face of the reverse nut 6. The reverse nut 6 is used to make the integral lead screw 5 move linearly. During operation, the integral lead screw 5 extends out of the reverse nut 6.

[0029] like Figure 4 As shown, the segmented roller 3 includes a first cylindrical roller portion 31, a first straight toothed roller portion 32, and a threaded roller portion 33, which are inserted into and connected to the cage through hole 22. A second cylindrical roller portion 34 and a second straight toothed roller portion 35 are disposed in the arc-shaped groove 42. The surfaces of the first straight toothed roller portion 32 and the second straight toothed roller portion 35 are threaded. The first straight toothed roller portion 32, the threaded roller portion 33, and the second straight toothed roller portion 35 mesh with and connect to the reverse-type nut 6. Please refer to [reference needed]. Figure 6This application presents a schematic diagram of a reverse nut. The outer edge of the reverse nut 6 includes a radially protruding ring for stable clamping, and bearings are installed on the front and rear outer edges. The internal thread of the reverse nut 6 has a multi-start structure, and the number of thread starts depends on the process and load-bearing capacity, generally 3 or 4 starts. In this embodiment, it has 3 starts. During operation, the reverse planetary roller screw runs, and the external hollow cup motor is attached to the outer edge of the reverse nut 6. The hollow cup motor drives the reverse nut 6 to rotate circumferentially. The reverse nut 6 drives the segmented roller 3 to rotate by meshing with the first roller straight tooth portion 32, the roller thread portion 33, and the second roller straight tooth portion 35 through the internal thread.

[0030] Please refer to Figure 5 This application presents a schematic diagram of an integral lead screw. The integral lead screw 5 is designed as a single structure, with a hollow interior for lightweight design. It has an internal thread at the tail end for connection with a fisheye bearing. The integral lead screw 5 includes a first cylindrical portion 51 penetrating the central through hole 21, a first spur tooth portion 52 meshing with the first roller spur tooth portion 32, a threaded portion 53 meshing with the roller threaded portion 33, a second cylindrical portion 54 disposed in the open-type retainer 4, a second spur tooth portion 55 meshing with the second roller spur tooth portion 35, and a long cylindrical body 56. The first cylindrical portion 51, the first spur tooth portion 52, and the lead screw... The threaded portion 53, the second lead screw cylindrical portion 54, the second lead screw spur tooth portion 55, and the lead screw long column 56 are integrally formed. During operation, the segmented roller 3 revolves around the integral lead screw 5 along with the annular cage 2 and the open cage 4. The roller thread portion 33 of the segmented roller 3 meshes with the lead screw thread portion 53 of the integral lead screw 5, causing the integral lead screw 5 to move axially reciprocally, that is, linearly. The internal thread direction of the reverse nut 6 is opposite to that of the roller thread portion 33 of the segmented roller 3, and the internal thread direction of the reverse nut 6 is the same as that of the lead screw thread portion 53 of the integral lead screw 5.

[0031] The integral ball screw 5 described in this application improves strength compared to the split structure, enhancing the load-bearing capacity, transmission, and reliability of the reversible planetary roller screw. It also reduces the cost of split machining, assembly difficulty, and assembly steps. In terms of design, the helix angle of the roller thread portion 33 of the segmented roller 3 is the same as that of the ball screw thread portion 53 of the integral ball screw 5, ensuring that the segmented roller 3 not only rolls along the helical raceway of the integral ball screw 5 and the reverse nut 6, but also rotates around its own axis and the central axis of the integral ball screw 5. Furthermore, the use of PEEK material for the open-type cage 4 solves the problem that the open-type cage 4 cannot be installed in the integral ball screw 5 when the diameter of the long column 56 of the integral ball screw 5 is larger than the diameter of the open-type cage 4. This also reduces friction and resonance during operation, lowering operating noise.

[0032] Please refer to Figure 7 The schematic diagram of the retaining ring of this application shows that the roller screw also includes a retaining ring 1. The cylindrical part 51 of the first screw has an annular groove 57. The retaining ring 1 is disposed in the annular groove 57 for fixing and limiting the circular retainer 2. In this embodiment of the application, the retaining ring 1 is a C-shaped ring, but it cannot be used to limit this application. Only those that can stably fix and limit should be within the protection scope of this application.

[0033] It should be noted that in the description of the embodiments of this application, the terms "front," "rear," "left," "right," "up," "down," etc., indicating the orientation or positional relationship are 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. The terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0034] Due to the adoption of the above technical features, this utility model has the following advantages and positive effects compared with the prior art:

[0035] First, the structure of this application increases the strength of the integral lead screw, resulting in better rigidity;

[0036] Secondly, the integral screw machining process of this application solves the problem of defects in the segmented machining and assembly process;

[0037] Third, the integral lead screw of this application is an integral structure, which can be hollow inside, allowing for lightweight design.

[0038] The above-disclosed embodiments are merely preferred embodiments of the present utility model, but are not intended to limit the scope thereof. Any equivalent changes and modifications made by those skilled in the art without departing from the spirit and essence of the present utility model shall fall within the protection scope of the present utility model.

Claims

1. A reversible planetary roller screw, characterized in that, The roller screw includes a ring-type cage, multiple segmented rollers, an open-type cage, a one-piece screw, and a reverse-type nut. The annular retainer includes a central through hole and a plurality of retainer through holes evenly distributed along the circumferential direction; The open-type retainer includes an opening and a plurality of arc-shaped grooves evenly distributed along the outer edge of the circumference. The opening is used to open so that the open-type retainer fits into and connects to the integral lead screw. One end of the segmented roller is inserted into the cage through hole with clearance fit, and the other end of the segmented roller is disposed in the arc groove with clearance fit. One end of the integral lead screw, which passes through the central through hole, is disposed in the reverse nut, and the other end of the integral lead screw is disposed outside the end face of the reverse nut. The reverse nut is used to enable the integral lead screw to perform linear motion.

2. The reversible planetary roller screw as described in claim 1, characterized in that, The segmented roller includes a first cylindrical roller portion, a first straight toothed roller portion, a threaded roller portion, and a second cylindrical roller portion and a second straight toothed roller portion disposed in the arc-shaped groove. The surfaces of the first straight toothed roller portion and the second straight toothed roller portion are threaded, and the first straight toothed roller portion, the threaded roller portion, and the second straight toothed roller portion mesh with the reverse nut.

3. The reversible planetary roller screw as described in claim 2, characterized in that, The integral lead screw includes a first lead screw cylindrical portion that passes through and connects to the central through hole, a first lead screw spur tooth portion that meshes with the first roller spur tooth portion, a lead screw thread portion that meshes with the roller thread portion, a second lead screw cylindrical portion disposed in the open-type cage, a second lead screw spur tooth portion that meshes with the second roller spur tooth portion, and a lead screw long column.

4. The reversible planetary roller screw as described in claim 3, characterized in that, The roller screw also includes a retaining ring with a snap ring. The cylindrical part of the first screw has an annular groove, and the retaining ring with a snap ring is disposed in the annular groove to fix and limit the circular retainer.

5. The reversible planetary roller screw as described in claim 4, characterized in that, The helix angle of the threaded portion of the segmented roller and the threaded portion of the integral lead screw is the same.

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