Roller screw

Abstract

The utility model provides a roller screw. The roller screw comprises a main screw, a nut and a plurality of planetary rollers. The main screw is provided with external threads. An internal thread is arranged in the nut. A plurality of planetary rollers are disposed around the main screw, and roller threads of the planetary rollers engage the external threads of the main screw and the internal threads of the nut to form planetary motion relative to the main screw. Wherein elastic bodies are arranged at the two ends of the planetary pin roller respectively. The elastic body is arranged on the planetary roller in a pressed mode. Wherein the thread direction of the internal thread of the nut is the same as the thread direction of the pin roller thread of the planetary pin roller, and the thread direction of the external thread of the main screw is the same as or opposite to the thread direction of the internal thread of the nut and the thread direction of the pin roller thread of the planetary pin roller. By means of the configuration, the pin roller screw can be applied to a miniature or mini-specification linear transmission system, such as a planetary pin roller screw or a reverse pin roller screw.

Description

Technical Field

[0001] This utility model relates to the technical field of roller screws, and in particular to a roller screw for use in miniature or micro-sized linear transmission systems, such as planetary roller screws or reverse roller screws. Background Technology

[0002] The most common planetary roller screws or reverse roller screws are devices that transmit power by having multiple small rollers roll between a screw and a nut. These rollers rotate around the screw during operation, much like planets orbiting the sun, hence the name "planetary" design. To prevent slippage of each roller, a small gear is traditionally machined at both ends of each roller, which, together with a toothed ring inside the nut, meshes with each other to ensure synchronized rotation.

[0003] However, this design presents several problems in practical applications. First, if the screw is to be made very small, for example, used in miniature devices or precision instruments, then the gears at both ends of the roller must also become very small and compact. Micro gears are not only difficult to manufacture and have a low yield rate, but they also increase the overall cost.

[0004] Furthermore, the assembly of these gears and gear rings requires high precision. Even a slight deviation can easily cause the rollers to jam, slip, or even produce abnormal noise or damage, especially under high-speed or frequent movement conditions. Moreover, traditional structures require many parts, such as locating pins, fixing plates, gears, gear rings, etc., which are not only cumbersome to assemble but also relatively large in size, making them unsuitable for products with limited space.

[0005] In general, traditional planetary roller screws or reverse roller screws have many limitations in manufacturing, assembly and use, and they face significant bottlenecks, especially when miniaturization and mass production are required.

[0006] In summary, the applicant of this utility model has conceived and designed a roller screw to improve upon the deficiencies of the prior art, thereby enhancing its industrial application. Utility Model Content

[0007] The purpose of this invention is to provide a roller screw to improve the problems existing in the prior art.

[0008] To achieve the above objectives, this utility model provides a roller screw, comprising a main screw, a nut, and a plurality of planetary rollers. The main screw has an external thread. The nut has an internal thread. The plurality of planetary rollers are arranged around the main screw, and the roller threads of the planetary rollers engage with the external thread of the main screw and the internal thread of the nut to form a planetary motion relative to the main screw. Each end of the planetary roller is provided with an elastic body. The elastic body is a cylinder with a through hole at its center, and the elastic body is compressed and disposed on the planetary roller. The thread direction of the internal thread of the nut is the same as the thread direction of the roller threads of the planetary rollers, and the thread direction of the external thread of the main screw is the same as or opposite to the thread direction of the internal thread of the nut and the roller threads of the planetary rollers.

[0009] Preferably, the roller screw includes a squirrel cage bracket, which includes two ring parts and multiple connecting rods; the multiple connecting rods are fixed between the two ring parts; the squirrel cage bracket, multiple elastomers and multiple planetary rollers are pre-assembled into a module, and then assembled with the main screw and nut.

[0010] Preferably, the plurality of connecting rods are fixed between the two ring components by laser welding.

[0011] Preferably, the annular component has a positioning hole corresponding to the planetary roller; the elastic body is located between the threaded portion of the planetary roller and the annular component.

[0012] Preferably, the connecting rod is located between the two planetary rollers.

[0013] Preferably, the planetary roller has only one roller thread.

[0014] Preferably, the nut has only one internal thread.

[0015] Preferably, the roller screw includes two retaining rings, which are disposed inside the nut and located at both ends of the plurality of planetary rollers.

[0016] Preferably, the roller screw is used in micro or miniature linear transmission systems.

[0017] The technical features of this utility model will be described in detail below with reference to specific embodiments and accompanying drawings, so that those skilled in the art can easily understand the purpose, technical features and advantages of this utility model. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art to which this utility model pertains, other drawings can be obtained based on these drawings.

[0019] Figure 1 This is an exploded view of the roller screw of this utility model.

[0020] Figure 2 This is an exploded view of the first assembled state of the roller screw of this utility model.

[0021] Figure 3 This is an exploded view of the second assembled state of the roller screw of this utility model.

[0022] Figure 4 This is a schematic diagram of the roller screw assembly of this utility model.

[0023] Figure 5 This is a cross-sectional schematic diagram of the roller screw of this utility model.

[0024] The markings in the diagram indicate:

[0025] 1: Roller screw, 2: Main screw, 21: External thread, 3: Nut, 31: Internal thread, 4: Planetary roller, 41: Roller thread, 5: Elastomer, 6: Squirrel cage bracket, 61: Circular ring, 611: Positioning hole, 62: Connecting rod, 7: Retaining ring. Detailed Implementation

[0026] The advantages, features, and technical methods of this utility model will be more readily understood by referring to the exemplary embodiments and accompanying drawings. This utility model can be implemented in different forms and should not be construed as limited to the embodiments set forth herein. Rather, the embodiments provided will make the disclosure of this utility model more thorough, complete, and fully convey the scope of this utility model to those skilled in the art, and this utility model will be defined only by the appended claims.

[0027] It should be understood that although the terms "first," "second," etc., may be used in this utility model to describe various elements, components, regions, sections, layers, and / or parts, these elements, components, regions, sections, layers, and / or parts should not be limited by these terms or be considered important or preferred. These terms are only used to distinguish one element, component, region, section, layer, and / or part from another element, component, region, section, layer, and / or part.

[0028] It should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art to which this utility model pertains can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0029] Unless otherwise defined, all terms used in this invention (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and this invention, and will not be interpreted as having an idealized or overly formal meaning unless expressly defined herein.

[0030] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. As used in this specification and the appended claims, unless the context clearly indicates otherwise, the singular forms “a” and “the” are intended to include the plural forms.

[0031] Please refer to the following: Figures 1 to 5 . Figure 1 This is an exploded view of the roller screw of this utility model. Figure 2 , 3 This is an exploded view of the roller screw of this utility model in different states. Figure 4 This is a schematic diagram of the roller screw assembly of this utility model. Figure 5 This is a cross-sectional schematic diagram of the roller screw of this utility model.

[0032] As shown in the figure, the roller screw 1 of this utility model is mainly used in micro or miniature linear transmission systems, such as planetary roller screws or reverse roller screws. In this embodiment, a planetary roller screw is used as an example. Since the working principle of the reverse roller screw is the same as that of the planetary roller screw, it will not be described in detail here. The roller screw 1 of this utility model mainly includes a main screw 2, a nut 3, multiple planetary rollers 4, and an elastomer 5.

[0033] The main screw 2 has an external thread 21. The nut 3 has a through hole along the axial direction, and the inside of the through hole has an internal thread 31. The main screw 2 and the nut 3 are components well known or commonly used by those skilled in the art, and will not be described in detail here. It is worth mentioning that in this utility model, the nut 3 has only one internal thread 31.

[0034] Multiple planetary rollers 4 are arranged around the main screw 2, and the roller threads 41 of the planetary rollers 4 engage with the external thread 21 of the main screw 2 and the internal thread 31 of the nut 3 to form a planetary motion relative to the main screw 2. It is worth noting that in this invention, each planetary roller 4 has only one roller thread 41. The thread direction of the internal thread 31 of the nut 3 is the same as the thread direction of the roller thread 41 of the planetary rollers 4, and the thread direction of the external thread 21 of the main screw 2 is the same as or opposite to the thread direction of the internal thread 31 of the nut 3 and the roller thread 41 of the planetary rollers 4.

[0035] The elastic body 5 is disposed at both ends of the planetary roller 4. The two ends of the planetary roller 4 are connected by a roller thread 41, and each end of the roller thread 41 has a stepped cylindrical protrusion. The elastic body 5 is fitted onto the cylinder adjacent to the roller thread 41. It is worth noting that the elastic body 5 is a cylinder with a through hole in its center.

[0036] It is worth mentioning that the elastomer 5 is compressed and positioned on the planetary roller 4. The roller screw 1 includes a squirrel-cage bracket 6; the squirrel-cage bracket 6 includes two annular members 61 and multiple connecting rods 62. The annular members 61 are provided with positioning holes 611 corresponding to the planetary roller 4, so that the cylindrical portion of the planetary roller 4 away from the roller thread 41 can pass through the positioning holes 611. The multiple connecting rods 62 are fixed between the two annular members 61. The elastomer 5 is located between the threaded portion of the planetary roller 4 and the annular members 61, and preferably, the connecting rods 62 are positioned between the two planetary rollers 4.

[0037] like Figure 2 , 3 As shown. The cage-type support 6, multiple elastic bodies 5, and multiple planetary rollers 4 are pre-assembled into a module, which is then assembled with the main screw 2 and nut 3. Further, one of the ring parts 61 is first fixed to multiple connecting rods 62 using laser welding to form a semi-finished module; then, the planetary rollers 4 with elastic bodies 5 at both ends are placed into the semi-finished module, and another ring part 61 is fixed to the connecting rods 62 of the semi-finished module using laser welding to form a complete module.

[0038] Additionally, the roller screw 1 includes two retaining rings 7, which are subsequently disposed inside the nut 3 and located at both ends of the plurality of planetary rollers 4. Preferably, the retaining rings 7 may be C-shaped retaining rings.

[0039] This invention relates to a novel and practical solution to the problems of complex structure, difficult assembly, and unstable operation encountered by traditional planetary or reverse-type roller screws during miniaturization. The core principle of this invention lies in eliminating the complex fit between the internal threads of the nut with different pitches and the external threads of the roller and the toothed ring, as required by traditional designs. Instead, it utilizes a compressive and elastic element 5 to achieve stable rolling motion. Simultaneously, a one-piece molded squirrel-cage support 6 ensures that each planetary roller 4 operates smoothly in the correct position, ultimately achieving structural advantages of high stability, high assemblability, and high process efficiency.

[0040] Furthermore, the main structure of the entire roller screw 1 includes a hollow or solid main screw 2, with continuous threads, or external threads 21, machined on its outer periphery. These external threads 21 engage with the roller threads 41 of the planetary rollers 4 surrounding the screw 2 during overall movement. Correspondingly, a nut 3 is fitted around the main screw 2, and its interior also has internal threads 31 that match the main screw 2. Besides engaging with the planetary rollers 4, the nut 3 also serves as a fixing or transmission element for the overall structure. With this combination, the rolling of the planetary rollers 4 is simultaneously restricted by both internal and external threads, thus achieving stable planetary motion.

[0041] Between the main screw 2 and the nut 3, multiple planetary rollers 4 are arranged. The length of these planetary rollers 4 is slightly less than the total length of the nut 3, allowing them to be stably placed in the through hole or inner cavity of the nut 3. Each planetary roller 4 has a threaded section in its central part, also called the roller thread 41, which forms a precise fit with the external thread 21 of the main screw 2 and the internal thread 31 of the nut 3. When the main screw 2 rotates, the planetary rollers 4 are guided by the double threads and roll along the helix instead of sliding; this is the basic operating logic of this structure.

[0042] To ensure that the planetary rollers 4 do not slip or shift during rolling, each planetary roller 4 is equipped with an elastic body 5 at both ends. These elastic bodies 5 are typically made of elastic material and have a cylindrical sleeve-like structure with a through hole in the center for easy pressing into the ends of the planetary roller 4 for fixation. After these elastic bodies 5 are installed, they are slightly compressed due to a slight interference fit with the inside of the nut 3. It is this compression that allows the elastic body 5 to provide a continuous force (elastic restoring force) to the planetary roller 4, further pressing the planetary roller 4 stably into the threaded structure on both sides. In other words, the elastic body 5 is not just a simple cushioning structure, but through its own deformation characteristics, it maintains a tight seal between the planetary roller 4, the nut 3, and the main screw 2, thereby preventing the planetary roller 4 from slipping, shaking, or even disengaging from the meshing position due to vibration or gaps during rolling.

[0043] Furthermore, this invention adds a set of squirrel-cage brackets 6 to the outside of the planetary rollers 4. These squirrel-cage brackets 6 consist of two ring parts 61 and multiple connecting rods 62. Each ring part 61 has several equidistantly distributed positioning holes 611, the number of which is the same as that of the planetary rollers 4. The distance between the two ring parts 61 is slightly less than or just enough to accommodate the ends of the elastic body 5 and the planetary rollers 4. During assembly, technicians can first fit the elastic body 5 onto both ends or one end of each planetary roller 4, and then insert the planetary roller 4 into the corresponding positioning holes 611 on the ring part 61. Next, using welding or tight fitting, the other ring part 61 is fixed to the other end of the connecting rod 62, thus securing the overall structure through the connecting rod 62 between the two ring parts 61. In this way, the center lines of all the planetary rollers 4 are ensured to be perfectly parallel, avoiding uneven force distribution due to different angles during use. These connecting rods 62 are distributed between each planetary roller 4. They serve to both widen the spacing and maintain symmetry. After molding, the entire cage-type bracket 6 becomes an integrated module that can be directly assembled with the main screw 2 and nut 3.

[0044] This modular approach, which integrates the planetary rollers 4, the elastomer 5, and the cage-type support 6, significantly simplifies the assembly process. In traditional structures, each roller must be inserted into the nut individually, with the gears and internal gear rings aligned simultaneously—a cumbersome and time-consuming process. In contrast, this invention allows for pre-assembly of the entire module, enabling rapid assembly with a single insertion and positioning. Furthermore, since both ends of each planetary roller 4 are fixed between two ring components 61, their position will not loosen or shift even under vibration or repetitive motion.

[0045] This invention also includes two retaining rings 7 at both ends inside the nut 3. These two retaining rings 7 are located just outside the two ends of the entire module, forming a boundary to limit the displacement range of the module within the nut 3. The retaining rings 7 can be installed in the grooves on the inner wall of the nut 3 in the form of elastic C-rings or hole retaining rings. The installation method is simple, yet it effectively prevents the module from shifting or loosening under external force. In this way, not only can the module maintain stability during long-term operation, but it also avoids abnormal internal roller friction caused by axial misalignment.

[0046] Overall, when the roller screw of this invention is installed in a transmission device, as long as the main screw is driven by rotation, the nut will linearly shift due to the meshing action between the planetary rollers and the thread. This shift can be used for direct drive or reverse transmission, for example, in a reverse roller screw assembly mechanism. Its key advantage is that the planetary rollers will not slip or jam, ensuring stable rolling operation and maintaining overall accuracy and efficiency. Furthermore, the contact friction generated by the elastomer and the thread provides a natural damping effect, helping to absorb minor vibrations and extending service life.

[0047] More importantly, the elastomer and cage support used in this invention not only improve motion stability but also solve the high barrier to entry problem in traditional gear manufacturing. In micro-applications, manufacturing precision gears often faces problems such as difficult tolerance control, long processing time, and insufficient part strength. However, this invention completely eliminates the need for two-stage or different pitch internal threads and internal gear rings, instead using an elastomer for fit and structural guidance to ensure synchronization, fundamentally simplifying the manufacturing process and reducing costs.

[0048] Furthermore, the elastomer itself can be modified by changing the material and adjusting the hardness according to different application requirements. It can even be designed as a composite material with damping or shock absorption functions, so that this utility model can not only be applied to precision machinery, but also extended to medical equipment, wearable devices or high-frequency motion mechanisms.

[0049] In summary, the roller screw of this invention is structurally based on the concept of eliminating two-stage or differently pitched internal threads and internal gear rings, utilizing elastic compression and modular supports to achieve stable rolling. In operation, it maintains high efficiency without slippage, and in processing and assembly, it significantly reduces difficulty and cost. It is particularly suitable for application in space-constrained, high-precision micro linear transmission systems, representing an innovative and practical transmission technology.

[0050] In the several embodiments provided by this utility model, it should be understood that the disclosed device can be implemented in other ways. For example, the above embodiments can be arbitrarily combined and applied without conflict; for example, the device embodiments described above are merely illustrative, and the division of modules is merely a logical functional division, and there may be other division methods in actual implementation; for example, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0051] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one position or distributed across multiple positions. Some or all of the modules can be selected to achieve the purpose of the embodiment solution according to actual needs. Furthermore, the functional modules in the various embodiments of this utility model can be integrated into one module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0052] The above-described embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art to which this utility model pertains should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A roller screw, characterized in that, Include: The main screw has external threads; Nuts have internal threads. Multiple planetary rollers are arranged around the main screw, and the roller threads of the planetary rollers engage with the external thread of the main screw and the internal thread of the nut to form a planetary motion relative to the main screw; wherein, each end of the planetary roller is provided with an elastic body; the elastic body is a cylinder with a through hole in the center, and the elastic body is compressed and disposed on the planetary roller; The internal thread of the nut has the same thread direction as the roller thread of the planetary roller, and the external thread of the main screw has the same thread direction as or opposite to the internal thread of the nut and the roller thread of the planetary roller.

2. The roller screw according to claim 1, characterized in that, The roller screw includes a squirrel cage bracket, which includes two ring parts and multiple connecting rods; the multiple connecting rods are fixed between the two ring parts; the squirrel cage bracket, multiple elastomers and multiple planetary rollers are pre-assembled into a module, and then assembled with the main screw and nut.

3. The roller screw according to claim 2, characterized in that, The multiple connecting rods are fixed between the two ring components by laser welding.

4. The roller screw according to claim 3, characterized in that, The annular component is provided with positioning holes corresponding to the planetary rollers; the elastic body is located between the threaded portion of the planetary rollers and the annular component.

5. The roller screw according to claim 4, characterized in that, The connecting rod is located between the two planetary rollers.

6. The roller screw according to claim 1, characterized in that, The planetary roller has only one roller thread.

7. The roller screw according to claim 6, characterized in that, The nut has only one internal thread.

8. The roller screw according to any one of claims 2 to 7, characterized in that, The roller screw includes two retaining rings; the two retaining rings are disposed inside the nut and are respectively located at both ends of the plurality of planetary rollers.

9. The roller screw according to claim 8, characterized in that, The roller screw is used in micro or mini linear drive systems.

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