A new type of planetary roller screw

Abstract

The utility model discloses a novel planetary roller screw, including screw shaft and nut main part, screw shaft and nut main part thread cooperation, the inside both ends of nut main part are fixed and set retainer, and multiple planetary rollers are installed evenly along the circumference between two retainers, and the inside both ends of nut main part are fixed and set inner gear ring, and the both ends of planetary roller are engaged with inner gear ring respectively, the both ends of nut main part inner wall are provided with sealing groove, and sealing ring is embedded in sealing groove, and the both ends of nut main part are detachably connected with end cap, and end cap is axially limited to sealing ring. The sealing ring realizes radial positioning through the precise cooperation of the sealing groove of the both ends of nut main part and the second ring groove of retainer, and in combination with the axial pre -tightening force of end cap, the problem of easy deviation and falling of traditional sealing ring is solved completely.

Description

Technical Field

[0001] This utility model relates to the field of planetary roller screws, and more specifically, to a novel planetary roller screw. Background Technology

[0002] Planetary roller screws, as high-precision transmission devices, are widely used in CNC machine tools, industrial robots, aerospace equipment, and other fields. Their core advantages lie in achieving high load-bearing capacity and long service life through multi-roller load-sharing design and line contact characteristics. However, existing circulating planetary roller screws still face significant technical bottlenecks in practical applications: Firstly, traditional solutions use only a single sealing ring for internal protection, a design with obvious drawbacks. On the one hand, a single-layer sealing structure is insufficient to effectively prevent the intrusion of external dust and impurities, easily leading to raceway wear and jamming problems after long-term operation. On the other hand, the sealing ring is not reliably fixed to the screw nut, making it prone to axial displacement or detachment during operation due to vibration. This not only reduces sealing efficiency but may also cause equipment downtime due to missing parts. These problems are particularly prominent under complex operating conditions (such as frequent starts and stops, and high-speed reciprocating motion).

[0003] Therefore, how to solve the technical problems existing in the prior art has become an urgent problem for those skilled in the art. Utility Model Content

[0004] To address the problems existing in the prior art, the purpose of this utility model is to provide a new type of planetary roller screw, which has two sealing rings and is radially limited by the sealing groove on the inner wall of the nut body and the second ring groove on the cage, and axially limited by the end cap. This not only improves the sealing effect, but also makes it less prone to falling off during operation and less likely to be lost during disassembly and assembly.

[0005] To solve the above problems, the present invention adopts the following technical solution: A novel planetary roller screw includes a screw shaft and a nut body. The screw shaft is threadedly engaged with the nut body. Cages are fixed at both ends inside the nut body, and multiple planetary rollers are evenly installed circumferentially between the two cages. Internal gear rings are fixed at both ends inside the nut body, and the two ends of the planetary rollers respectively mesh with the internal gear rings. Sealing grooves are formed on the inner walls of both ends of the nut body, and sealing rings are embedded in the sealing grooves. End caps are detachably connected to both ends of the nut body, and the end caps axially limit the sealing rings.

[0006] Furthermore, an installation groove is formed on the inner wall of the nut body, and the internal gear ring is interference-fitted in the installation groove.

[0007] Furthermore, the internal gear ring has a structure consisting of two semi-circular arcs joined together, and an anti-rotation pin is provided between the internal gear ring and the nut body. Furthermore, an inner hoop ring is installed between the internal gear ring and the cage.

[0008] Furthermore, the retainer has a first annular groove on one side and a second annular groove on the other side, with the inner hoop ring installed in the first annular groove and the inner side of the sealing ring engaging with the second annular groove.

[0009] Furthermore, both ends of the planetary roller are provided with mating teeth, which mesh with the corresponding internal gear ring.

[0010] Furthermore, a connecting ring is provided on the outer wall of the nut body, and a connecting hole is provided on the connecting ring along the circumferential direction.

[0011] Furthermore, the sealing ring is a lip seal ring, which is made of a highly wear-resistant elastomer.

[0012] Furthermore, the outer wall of the end cap is provided with heat-conducting fins, and the inner wall is provided with a spiral dustproof groove.

[0013] Furthermore, the end cap is equipped with a miniature vent valve.

[0014] Compared with the prior art, this utility model provides a novel planetary roller screw, which has the following beneficial effects: 1. Employing a dual sealing mechanism of "radial limiting + axial compression," the sealing ring achieves radial positioning through the precise fit between the sealing grooves at both ends of the nut body and the second ring groove of the cage. Combined with the axial preload of the end cap, this completely solves the problem of traditional sealing rings being prone to displacement and detachment. Experimental verification shows that this structure can control the positional deviation of the sealing ring within 0.05mm under vibration conditions, and reduces the sealing ring loss rate to zero during disassembly and assembly, significantly improving the long-term operational reliability of the equipment. 2. The sealing ring adopts a lip seal, which automatically conforms to the sealing surface under working pressure, forming a dynamic compensation effect. Actual test data shows that within a temperature range of -20℃ to 80℃, the sealing ring can maintain stable contact pressure, effectively preventing seal failure caused by thermal expansion and contraction, and adapting to a wide temperature range working environment. 3. The combination of segmented internal gear ring design and anti-rotation pins reduces the assembly time of the internal gear ring by about 40% while eliminating the risk of circumferential sliding. 4. The detachable end cap and sealing ring assembly structure allows for sealing ring replacement without disassembling the entire lead screw assembly, significantly reducing maintenance complexity. Attached Figure Description

[0015] Figure 1 This is a perspective view of the present utility model; Figure 2 This is a perspective view of the nut assembly of this utility model; Figure 3 This is an exploded view of the nut body of this utility model; Figure 4This is a partially exploded view of the nut body of this utility model; Figure 5 This is a cross-sectional view of the nut body of this utility model; Figure 6 for Figure 5 A magnified view of a portion of point A in the middle.

[0016] Explanation of the labels in the diagram: 1. Lead screw shaft; 2. Nut body; 201. Sealing groove; 202. Mounting groove; 3. Connecting ring; 4. Internal gear ring; 5. Planetary roller; 6. Mating gear; 7. Cage; 701. First ring groove; 702. Second ring groove; 8. Inner hoop ring; 9. Sealing ring; 10. End cap; 12. Connecting hole; 13. Anti-rotation pin. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present utility model, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0018] Please see Figures 1-6 A novel planetary roller screw includes a screw shaft 1 and a nut body 2. The screw shaft 1 is threadedly engaged with the nut body 2. Cages 7 are fixed at both ends inside the nut body 2. Multiple planetary rollers 5 are evenly installed circumferentially between the two cages 7. The outer surface of the planetary rollers 5 slides against the inner wall of the nut body 2. Internal gear rings 4 are fixed at both ends inside the nut body 2, and the two ends of the planetary rollers 5 mesh with the internal gear rings 4 respectively. Sealing grooves 201 are formed on the inner walls at both ends of the nut body 2, and sealing rings 9 are embedded in the sealing grooves 201. End caps 10 are detachably connected to both ends of the nut body 2, and the end caps 10 axially limit the sealing rings 9.

[0019] In this embodiment, the lead screw shaft 1 is the transmission input shaft, and its outer wall forms a threaded pair with the nut body 2. A connecting ring 3 extends from the outer wall of the nut body 2, and a connecting hole 12 is opened along the circumferential direction on the connecting ring 3, allowing the equipment to be installed externally. The retainers 7 are arranged in pairs at both ends inside the nut body 2, and their main function is to fix the planetary rollers 5 in a predetermined position to ensure precise meshing between the planetary rollers 5 and the internal gear ring 4.

[0020] The retainer 7 has a first annular groove 701 on one side and a second annular groove 702 on the other side. The inner hoop 8 is installed in the first annular groove 701, and the inner side of the sealing ring 9 mates with the second annular groove 702. Specifically, the outer side of the sealing ring 9 is embedded in the annular sealing groove 201, and the inner side is embedded in the second annular groove 702, forming a radial bidirectional limiting. The two ends of the nut body 2 are detachably connected to end caps 10, which are fastened to the nut body 2 by bolts, applying an axial preload to the sealing ring 9 to ensure that the sealing ring 9 always fits tightly against the sealing surface and completely eliminates axial displacement of the sealing ring 9 caused by vibration.

[0021] The sealing ring 9 is a lip-shaped sealing ring made of high wear-resistant elastomer. Under working pressure, it automatically fits the sealing surface, effectively compensating for gaps caused by temperature changes or wear, and ensuring long-term sealing reliability.

[0022] The internal gear ring 4 adopts a two-half-circular arc splicing design, and the inner wall of the nut body 2 has an installation groove 202, in which the internal gear ring 4 is interference-fitted. This design significantly simplifies the assembly process, eliminating the need for the complex press-fitting process of the integral internal gear ring 4.

[0023] An anti-rotation pin 13 is provided between the internal gear ring 4 and the nut body 2 to prevent the internal gear ring from sliding circumferentially during operation and to ensure transmission accuracy.

[0024] An inner ring 8 is installed between the internal gear ring 4 and the cage 7. The inner ring is engaged in the first ring groove 701 of the cage 7, which further enhances the structural rigidity of the internal gear ring 4 and avoids the risk of deformation during high-speed operation.

[0025] Both ends of the planetary rollers 5 are equipped with mating teeth 6, which mesh with the internal gear rings 4 at both ends. When the lead screw shaft 1 rotates, the mating teeth 6 at both ends of the planetary rollers 5 are always engaged with the internal gear rings 4, forcing the planetary rollers 5 to maintain the correct radial position. The internal gear rings 4 absorb lateral forces through tooth surface contact, avoiding jamming or wear caused by uneven loading of the planetary rollers 5, and effectively suppressing the impact of vibration and impact on transmission accuracy. Multiple planetary rollers 5 are evenly arranged circumferentially, and the load is evenly distributed through the guiding action of the cage 7, reducing single-point contact stress and extending service life. The internal gear rings 4 provide radial positioning and circumferential limiting for the planetary rollers 5, preventing planetary roller offset or tilting, while evenly distributing the load to all planetary rollers. The internal gear rings 4 only serve as a static guiding mechanism, significantly reducing manufacturing difficulty and maintenance costs.

[0026] The outer wall of the end cap 10 is provided with heat-conducting fins (not shown in the figure) to accelerate the dissipation of internal heat; the inner wall is machined with spiral dustproof grooves (not shown in the figure) to form a labyrinth cavity structure, which effectively prevents external dust from entering along the shaft gap.

[0027] The end cap 10 is equipped with a miniature vent valve (not shown in the figure) to balance the air pressure inside and outside the nut body 2, prevent condensation from accumulating due to temperature difference, and avoid excessive internal pressure from affecting the sealing performance.

[0028] Assembly process of this utility model: 1. The segmented internal gear ring 4 is embedded into the mounting groove on the inner wall of the nut body 2 by interference fit, and then fixed by anti-rotation pins; 2. Place the planetary roller 5 between the two cages 7 so that its mating teeth 6 mesh with the internal gear ring 4; 3. Embed the sealing ring 9 into the sealing groove on the inner wall of the nut body 2, and snap its inner side into the second annular groove of the retainer 7; 4. Align the end cap 10 with both ends of the nut body 2, apply axial preload through the bolts, and compress the sealing ring 9 to complete the seal.

[0029] In actual operation, the nut body 2 is driven by the screw shaft 1 and moves linearly along the axis of the screw shaft 1. Since the outer surface of the planetary roller 5 is in sliding fit with the inner wall of the nut body 2, when the nut body 2 moves, the friction force forces the planetary roller 5 to rotate continuously around its own axis. The cage 7 restricts the axial movement of the planetary roller 5 and ensures that the planetary roller 5 is stably located inside the nut body 2. The planetary roller 5 meshes with the internal gear ring 4 through the mating teeth 6. The internal gear ring 4 constrains the radial position of the planetary roller 5 and prevents the planetary roller 5 from shifting or tilting.

[0030] This invention employs a dual-limiting + dynamic compensation sealing system, solving the problems of easy displacement and detachment of traditional single rubber rings. The segmented internal gear ring and quick-release end cap design significantly shortens assembly time and reduces maintenance difficulty. The synergistic effect of heat-conducting fins, dustproof grooves, and vent valves enables stable operation of the equipment under complex conditions such as dust and temperature differences. Anti-rotation pins eliminate the risk of circumferential sliding of the internal gear ring, ensuring transmission accuracy. Because the cage is fixed, the center position of the planetary rollers remains constant, thus eliminating the "planetary gears revolving around the sun gear" motion characteristic of traditional planetary gear systems. The internal gear ring 4 directly drives the planetary rollers to rotate, eliminating the complex motion mechanism of traditional planetary carriers, reducing manufacturing difficulty and maintenance costs, and achieving structural simplification, improved sealing, and enhanced reliability. This design is particularly suitable for industrial scenarios with compact axial dimensions, low maintenance frequency, and strong environmental adaptability.

[0031] The control method of this utility model is to control the device by manually starting and stopping the switch. The wiring diagram of the power element and the supply of power are common knowledge in the field. Since this utility model is mainly used to protect mechanical devices, the control method and wiring layout will not be explained in detail.

[0032] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model based on the technical solution and its improved concept should be covered within the protection scope of the present utility model.

Claims

1. A novel planetary roller screw, characterized in that: The nut body includes a lead screw shaft (1) and a nut body (2). The lead screw shaft (1) is threadedly engaged with the nut body (2). The nut body (2) has retainers (7) fixed at both ends inside. Multiple planetary rollers (5) are evenly installed circumferentially between the two retainers (7). An internal gear ring (4) is fixed at both ends inside the nut body (2). The planetary rollers (5) mesh with the internal gear ring (4) at both ends. A sealing groove is provided on the inner wall of both ends of the nut body (2). A sealing ring (9) is embedded in the sealing groove. End caps (10) are detachably connected to both ends of the nut body (2). The end caps (10) limit the axial movement of the sealing ring (9).

2. The novel planetary roller screw according to claim 1, characterized in that: The nut body (2) has an installation groove on its inner wall, and the internal gear ring (4) is interference-fitted in the installation groove.

3. A novel planetary roller screw according to claim 2, characterized in that: The internal gear ring (4) is a structure of two semi-circular arcs spliced ​​together, and an anti-rotation pin is provided between the internal gear ring (4) and the nut body (2).

4. A novel planetary roller screw according to claim 3, characterized in that: An inner hoop ring (8) is installed between the internal gear ring (4) and the cage (7).

5. A novel planetary roller screw according to claim 4, characterized in that: The retainer (7) has a first annular groove on one side and a second annular groove on the other side. The inner hoop (8) is installed in the first annular groove, and the inner side of the sealing ring (9) is engaged with the second annular groove.

6. A novel planetary roller screw according to claim 5, characterized in that: Both ends of the planetary roller (5) are provided with mating teeth (6), which mesh with the corresponding internal gear ring (4).

7. A novel planetary roller screw according to claim 5, characterized in that: The outer wall of the nut body (2) is provided with a connecting ring (3), and the connecting ring (3) has a connecting hole (12) along the circumferential direction.

8. A novel planetary roller screw according to claim 5, characterized in that: The sealing ring (9) is a lip-type sealing ring, which is made of a highly wear-resistant elastomer.

9. A novel planetary roller screw according to claim 5, characterized in that: The outer wall of the end cap (10) is provided with heat-conducting fins, and the inner wall is provided with a spiral dustproof groove.

10. A novel planetary roller screw according to claim 5, characterized in that: The end cap (10) is equipped with a miniature vent valve.

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