Toothless planetary roller screw pair

Abstract

This invention relates to a toothless planetary roller screw pair, comprising a planetary nut, a planetary screw, and a plurality of planetary rollers disposed between the planetary nut and the planetary screw. Each planetary roller has a threaded portion in its center that mates with the planetary screw and the planetary nut. Each planetary roller has several annular grooves distributed axially at both ends. Each planetary nut has several annular grooves at both ends that mate with the annular grooves of the planetary rollers. The annular grooves and annular grooves can slide relative to each other. This invention uses annular grooves and annular grooves at both ends to form a sliding raceway contact pair, replacing the traditional gear-internal gear ring mating structure. The contact between the annular grooves and annular grooves ensures complete contact across the entire raceway, resulting in strong load-bearing capacity and significantly improving the rollers' resistance to eccentric loading and skewing. Furthermore, the mating clearance between the annular grooves and annular grooves can be machined and controlled according to actual working conditions, resulting in higher constraint and limiting accuracy, stronger stability and impact resistance, and significantly reduced machining and assembly difficulty.

Description

Technical Field

[0001] This invention relates to a toothless planetary roller screw pair, belonging to the technical field of planetary roller screw pairs. Background Technology

[0002] Planetary roller screw pairs are high-precision transmission devices that convert rotary motion into linear motion. They possess excellent properties such as high load capacity, high rigidity, and long service life, and are widely used in aerospace, defense, machinery manufacturing, new energy, and electric vehicle production.

[0003] Because the helix angles of the planetary screw and the planetary roller thread raceway are inconsistent, the rollers will be subjected to eccentric loads during operation, causing them to run skewed. To solve this problem, the traditional method is to machine external gears at both ends of the rollers and install internal gear rings that mesh with the external gears at both ends of the planetary nut. The gear meshing constrains the state of the rollers and prevents them from deflecting or skewing during operation.

[0004] The existing gear-internal gear ring mating structure has limited effect on suppressing roller misalignment, cannot provide sufficient multi-point constraint, and has limited load-bearing capacity; at the same time, due to the existence of backlash, it is greatly affected by impact conditions.

[0005] Moreover, the gear pair requires high machining precision, especially the phase consistency of the gears on both sides of the roller needs to be strictly controlled to ensure the synchronization of the gear transmission on both sides, resulting in low yield and high processing cost. Furthermore, due to the phase problem involving the multi-start thread raceway and the gear pair, it is difficult to control the phase consistency of the roller gear phase and its thread raceway during batch processing, which makes it difficult to guarantee consistency during batch assembly, resulting in high assembly difficulty, low assembly error tolerance and efficiency. Summary of the Invention

[0006] In order to solve the problems existing in the prior art, the present invention proposes a toothless planetary roller screw pair with a sliding raceway contact pair.

[0007] To achieve the above objectives, the technical solution proposed by this invention is as follows: A toothless planetary roller screw pair includes a planetary nut, a planetary screw, and a plurality of planetary rollers disposed between the planetary nut and the planetary screw. The planetary rollers have threads in the middle that mate with the planetary screw and the planetary nut, and a plurality of annular protrusions distributed axially at both ends of the planetary rollers. The planetary nut has a plurality of annular grooves at both ends that mate with the annular protrusions of the planetary rollers, and the annular protrusions and annular grooves can slide relative to each other.

[0008] A further design of the above technical solution is as follows: the cross-section of the annular groove is convex arc-shaped, and the cross-section of the annular groove is triangular.

[0009] A preferred embodiment of the above technical solution is that the annular groove is formed by slotting the inner surface of the planetary nut.

[0010] Another preferred embodiment of the above technical solution is: the planetary nut has an inner ring on the inner side of both ends, and the annular groove is formed on the inner surface of the inner ring.

[0011] The annular groove is either a continuous circumferential groove or a segmented circumferential groove.

[0012] The annular groove is provided on the journal section at both ends of each roller, and the annular groove is a continuous circumferential convex surface or a segmented circumferential convex surface.

[0013] Compared with the prior art, the present invention has the following advantages: This invention uses an annular convex groove and an annular groove to form a sliding raceway contact pair, replacing the traditional gear-internal gear ring mating structure. The contact between the annular convex groove and the annular groove can ensure complete contact of the entire circle, resulting in strong load-bearing capacity and significantly improving the roller's ability to resist eccentric loads and skewing. At the same time, the mating clearance between the annular convex groove and the annular groove can be machined and controlled according to actual working conditions, resulting in higher constraint and limiting accuracy, and stronger stability and impact resistance.

[0014] Meanwhile, the fit between the annular protrusion and the annular groove does not require consideration of the synchronization of the gears on both sides, making the processing difficult. The annular protrusion can be processed by extrusion or rolling, resulting in high production efficiency, good stability, and reduced manufacturing costs.

[0015] The engagement of the annular protrusion and annular groove also eliminates the phase matching issue with the thread raceway, making alignment convenient and eliminating the need for precise matching of gear meshing phases. This significantly reduces assembly difficulty and greatly improves assembly efficiency, resulting in better consistency in batch assembly. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the toothless planetary roller screw pair of the present invention; Figure 2 for Figure 1 A magnified view of a portion of the image; Figure 3 This is a schematic diagram showing the fit between the annular protrusion and the annular groove; In the diagram: 1-planetary screw, 2-planetary nut, 21-annular groove, 3-planetary roller, 31-annular protrusion, 4-cage, 5-seal ring. Detailed Implementation

[0017] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0018] In the description of the embodiments of the present invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are used only for the convenience of describing the present invention 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. Therefore, they should not be construed as limitations on the invention. The accompanying drawings are schematic diagrams or conceptual diagrams, and the relationships between the thickness and width of each part, as well as the proportional relationships between each part, etc., are not entirely consistent with their actual values. Example 1

[0019] The toothless planetary roller screw pair in this embodiment, such as Figure 1 and Figure 2 As shown, the system includes a planetary nut 2, a planetary screw 1, and multiple planetary rollers 3 disposed between the planetary nut 2 and the planetary screw 1. The planetary rollers 3 have threads in the middle that mate with the planetary screw 1 and the planetary nut 2. The journal sections at both ends of the planetary rollers 3 have annular grooves 31 arranged circumferentially. Several annular grooves 31 are distributed along the axial direction of the planetary rollers 3. The planetary nut 2 has several annular grooves 21 at both ends that mate with the annular grooves 31 at both ends of the planetary rollers 3. Correspondingly, the annular grooves 21 are arranged circumferentially along the planetary nut 2 and several are distributed along the axial direction of the planetary nut 2. During the revolution and rotation of the planetary rollers 3, the annular grooves 31 at both ends are just embedded in the annular grooves 21, and the annular grooves and annular grooves can slide relative to each other, forming a sliding raceway contact pair, which provides constraint on the planetary rollers 3 and prevents the planetary rollers 3 from skewing during operation.

[0020] In this embodiment, the annular groove 21 is formed by slotting the inner surfaces at both ends of the planetary nut 2, eliminating the need for the traditional internal gear ring structure. The annular groove is a continuous circumferential groove, and the corresponding annular convex groove is also a continuous circumferential convex surface.

[0021] This embodiment uses an annular convex groove and an annular groove to form a sliding raceway contact pair, which can ensure complete contact around the entire circle, has a strong load-bearing capacity, and significantly improves the roller's ability to resist eccentric loads and skewing. At the same time, the fit clearance between the convex arc surface annular convex groove and the annular groove can be machined and controlled according to the actual working conditions, resulting in higher constraint and positioning accuracy.

[0022] Because this embodiment uses the combination of annular protrusion and annular groove, there is no need to consider the synchronization of the gears on both sides, or the phase matching problem of not meshing with the thread raceway. The processing difficulty is low, the alignment is convenient, and there is no need to accurately match the gear meshing phase. The assembly difficulty is greatly reduced while the assembly efficiency is greatly improved, and the consistency of batch assembly is better. Example 2

[0023] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the inner ring (similar to the internal gear ring in a traditional structure) is provided on the inner side of both ends of the planetary nut 2. The annular groove 21 is opened on the inner surface of the inner ring. Multiple planetary nuts 3 are arranged circumferentially between the planetary screw 1 and the planetary nut 2 by the retainer 4, and the inner ring and the retainer are fixed to the inner side of the planetary nut 2 by the snap ring. Sealing rings are provided at both ends of the planetary nut 2 for sealing.

[0024] Combination Figure 3 As shown, in this embodiment, the cross-section of the annular groove 31 is convex arc-shaped, and the cross-section of the annular groove 21 is triangular, so that the relative sliding friction is smaller after the two are fitted together; the convex arc-shaped annular groove can be processed by extrusion or rolling, which has high production efficiency, good stability, and reduces manufacturing costs. The annular groove 21 is a segmented groove arranged circumferentially, and the corresponding annular convex groove 31 is also a segmented convex surface arranged circumferentially.

[0025] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A toothless planetary roller screw pair comprising a planetary nut, a planetary screw, and a plurality of planetary rollers disposed between the planetary nut and the planetary screw, characterized in that: The planetary roller has a thread in the middle that mates with the planetary screw and planetary nut, and several annular grooves are distributed along the axial direction at both ends of the planetary roller; the planetary nut has several annular grooves at both ends that mate with the annular grooves of the planetary roller, and the annular grooves and annular grooves can slide relative to each other.

2. The toothless planetary roller screw pair of claim 1, wherein: The annular groove has a convex arc cross-section, and the annular recess has a triangular cross-section.

3. A toothless planetary roller screw pair according to claim 2, characterized in that: The annular groove is formed by slotting the inner surface of the planetary nut.

4. The toothless planetary roller screw pair according to claim 2, characterized in that: The planetary nut has an inner ring on the inner side of both ends, and the annular groove is formed on the inner surface of the inner ring.

5. The toothless planetary roller screw pair according to claim 3 or 4, characterized in that: The annular groove is either a continuous circumferential groove or a segmented circumferential groove.

6. The toothless planetary roller screw pair according to claim 5, characterized in that: The annular groove is provided on the journal section at both ends of each roller, and the annular groove is a continuous circumferential convex surface or a segmented circumferential convex surface.

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