A pin-fixed retainer and planetary roller screw pair

Abstract

This utility model relates to the field of high-precision transmission technology, specifically disclosing a pin-fixed cage and a planetary roller screw assembly. The cage includes an annular cage base with a central hole and multiple roller limiting holes evenly distributed along its circumference. The cage base also has at least two pin holes distributed along its circumference. It further includes a pin that is adapted to and installed within the pin holes. When the pin is installed in the pin holes, a portion of it extends inward into the central hole. This structure achieves axial positioning through the pin, breaking away from the traditional two-sided positioning design. While ensuring circumferential rotational freedom, it simplifies the overall structure. Even under the harsh conditions of miniaturized planetary roller screw assemblies, the pin structure still ensures the reliable connection between the cage and the screw or nut, maintaining excellent operational stability.

Description

Technical Field

[0001] This utility model relates to the field of high-precision transmission technology, specifically to a pin-fixed cage and a planetary roller screw pair. Background Technology

[0002] In traditional planetary roller screw assemblies, the axial positioning of the cage typically relies on the engagement of a retaining circlip and a gear step, ensuring normal rotation on the smooth section of the screw or the inner wall of the nut and preventing axial movement. However, as planetary roller screw assemblies evolve towards miniaturization and micro-miniaturization, the retaining circlip fixing method faces the following technical bottlenecks:

[0003] (1) Insufficient mechanical properties of snap rings: In miniaturized designs, the wire diameter ratio of snap rings is usually less than 1:10, which leads to a significant decrease in their stiffness and elasticity, making it difficult to provide effective axial support;

[0004] (2) Difficult to install and disassemble: After the size of the snap ring is reduced, the difficulty of its installation and disassembly increases sharply, which seriously affects the assembly efficiency and maintenance convenience;

[0005] (3) Interference with rollers: In a compact layout, the snap ring is very likely to interfere with the adjacent rollers in space, and may even be unable to be assembled smoothly;

[0006] (4) Weakened gear step limiting function: Miniaturization leads to a significant reduction in the height of the gear step (e.g., less than 0.5 mm), which cannot provide sufficient axial resistance for the cage. Summary of the Invention

[0007] This invention aims to solve the problems of poor stability, low reliability, difficult assembly and disassembly, and easy interference with rollers caused by the use of snap rings and gear steps to fix the cage in the miniaturization design of existing planetary roller screw pairs.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a pin-fixed retainer, comprising an annular retainer base, wherein the retainer base is provided with a central hole, and the retainer base is provided with a plurality of roller limiting holes evenly distributed along its circumference; the retainer base is also provided with at least two pin holes distributed along its circumference; and further comprising a pin, wherein the pin is adapted to the pin holes and installed in the pin holes; when the pin is installed in the pin holes, a portion thereof extends inward into the central hole.

[0009] In a preferred embodiment, the pin hole extends radially from the outer circumferential surface of the retainer base to the central hole, the length of the pin is greater than the length of the pin hole, and when the pin is installed in the pin hole, one end of it extends inward into the central hole.

[0010] In a preferred embodiment, the pin holes are evenly distributed along the circumferential direction of the cage base.

[0011] In a preferred embodiment, the axis of the pin hole intersects the axis of the central hole perpendicularly in space, both ends of the pin hole penetrate the outer circumferential surface of the cage base, and the pin hole partially intersects the central hole in the radial direction; when the pin is installed in the pin hole, a portion of it extends radially inward into the central hole.

[0012] In a preferred embodiment, there are two pin holes that are symmetrical to each other.

[0013] This utility model also discloses a planetary roller screw pair, including a nut, a screw, a plurality of rollers disposed between the nut and the screw, and a pair of retainers for limiting the rollers; both ends of the rollers are provided with smooth rod sections, which are accommodated in the roller limiting holes of the retainers; the retainers are the pin-fixed retainers described above, and the screw is provided with a first annular groove for accommodating the pin; when the pin is installed in the pin hole, the portion of it extending into the central hole extends into the first annular groove.

[0014] This utility model also discloses a planetary roller screw pair, including a nut, a screw, a plurality of rollers disposed between the nut and the screw, and a pair of retainers for limiting the rollers; both ends of the rollers are provided with smooth rod sections, which are accommodated in the roller limiting holes of the retainers; the retainers are the pin-fixed retainers described above, and the inner wall of the nut is provided with a second annular groove for accommodating the pin; when the pin is installed in the pin hole, the portion of it extending into the central hole extends into the second annular groove.

[0015] Compared with the prior art, the pin-fixed cage and planetary roller screw pair of this utility model have the following advantages:

[0016] (1) Innovative structure and reliable positioning: Axial positioning is achieved by the cooperation of the pin and the screw or nut groove, breaking through the traditional mindset of two-sided positioning. While ensuring the degree of freedom of circumferential rotation, the overall structure is simplified.

[0017] (2) Easy to install and disassemble, and improved efficiency: The matching structure of the pin and the hole significantly simplifies the installation and disassembly process, and is more time-saving and labor-saving than the snap ring method.

[0018] (3) Adaptable to miniaturization and stable performance: Even under the harsh working conditions of miniaturized planetary roller screw pairs, the pin structure can still ensure the reliability of the connection between the cage and the screw or nut, and maintain excellent operating stability.

[0019] (4) Controllable precision and excellent assembly: By precisely setting the fit tolerance between the pin and the ring groove, the axial installation clearance can be actively adjusted, effectively overcoming the shaking problem caused by the inherent clearance of the traditional snap ring and improving the assembly precision.

[0020] (5) Enhanced rigidity and elimination of movement: The pin structure provides a more rigid axial connection for the cage, which fundamentally eliminates the risk of axial movement caused by loose snap rings or assembly errors, and significantly enhances axial stability. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the cage structure shown in Embodiment 1; Figure 2 This is a schematic diagram of the planetary roller screw pair with a cage as shown in Example 1. Figure 3 for Figure 2 A cross-sectional schematic diagram of the planetary roller screw pair shown; Figure 4 for Figure 2 The diagram shows the structure of the lead screw in the planetary roller screw pair. Figure 5 This is a schematic diagram of the cage structure shown in Embodiment 2; Figure 6 for Figure 5 Side view of the cage shown; Figure 7 for Figure 6 Left view of the cage shown; Figure 8 This is a schematic diagram of the structure of a planetary roller screw pair with a cage as shown in Embodiment 2. Figure 9 for Figure 8 A partial cross-sectional view of the planetary roller screw pair shown. Figure 10 This is a partial cross-sectional view of the planetary roller screw pair with a cage, as shown in another application embodiment 2. Figure 11 This is a schematic diagram of the structure of the planetary roller screw pair of the cage shown in another application embodiment 2; Figure 12 for Figure 11 The diagram shows the structure of a planetary roller screw pair. Figure 13 This is a schematic diagram of the cage structure shown in Embodiment 3; Figure 14 for Figure 13 A schematic cross-sectional view of the cage shown. Figure 15 This is a schematic diagram of the structure of a planetary roller screw pair with a cage as shown in Embodiment 3. Figure 16 for Figure 15 The diagram shows the structure of the planetary roller screw pair after the nut and cage are hidden. Figure 17 for Figure 15 The diagram shows a cross-sectional view of the planetary roller screw pair. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0023] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "rear", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model 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 this utility model.

[0024] In the description of this utility model, 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 a fixed connection, an integral connection, or a detachable connection; they can refer to the internal connection of two components; they can refer to a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0025] Example 1

[0026] This embodiment provides a pin-fixed retainer 10, such as... Figure 1 As shown, it includes an annular retainer base 11, which has a central hole 12 for receiving the lead screw.

[0027] In this embodiment, the cage base 11 is provided with a plurality of roller limiting holes 13 evenly distributed along its circumference, and the roller limiting holes 13 axially penetrate the cage base 11.

[0028] As a special feature of this embodiment, the cage base 11 is also provided with two pin holes 14 evenly distributed along its circumference. The pin holes 14 extend radially from the outer circumferential surface of the cage base 11 to the central hole 12.

[0029] Of course, only two pin holes 14 are provided in this embodiment. In actual applications, the number of pin holes 14 can be set to more as needed.

[0030] A planetary roller screw pair using the cage of this embodiment, such as Figure 2 , Figure 3 As shown, it includes a nut 20, rollers 40, a lead screw 30, and a retainer 10 as shown in Embodiment 1. The plurality of rollers 40 are confined between the nut 20 and the lead screw 30 by a pair of opposing retainers 10.

[0031] In this embodiment, as Figure 2 As shown, the roller 40 includes a threaded section 41, a gear-thread composite structure 42 located on both sides of the threaded section 41, and a smooth rod section 43 located outside the gear-thread composite structure 42. The smooth rod section 43 is located in the roller limiting hole 13 of the cage 10.

[0032] In this embodiment, the structure of the lead screw 30 is as follows: Figure 4 As shown, the device includes a lead screw body 31, on which a lead screw thread section 32 is provided. Gears 33 are provided on both sides of the lead screw thread section 32. The gears 33 are used to mesh with the gears in the gear-thread composite structure 42 on the roller 40. First annular grooves 34 are provided on both sides of the gears 33.

[0033] In this embodiment, a pin 50 is also included. The pin 50 is adapted to and installed in the pin hole 14, and the length of the pin 50 is greater than the length of the pin hole 14. When the pin 50 is installed in the pin hole 14, one end of it extending into the central hole 12 extends into the first annular groove 34, thereby realizing the assembly between the retainer 10 and the lead screw 30, and limiting the retainer in the axial direction.

[0034] In this embodiment, preferably, the pin 50 does not contact the bottom of the first annular groove 34 to reduce running friction.

[0035] It should be noted that the pin 50 and the pin hole 14 can be fixed by existing technologies such as interference fit, adhesive bonding, welding or riveting.

[0036] In this embodiment, the cage is axially positioned by a pin engaging with an annular groove. Compared with traditional end face / step positioning, this implementation can avoid friction on the end face of the cage, thereby preventing wear and folding of the end face.

[0037] Example 2

[0038] This embodiment provides a pin-fixed retainer, such as... Figures 5-7 As shown, it includes an annular retainer base 11, which has a central hole 12 for receiving the lead screw.

[0039] In this embodiment, one end of the retainer base 11 is provided with a plurality of roller limiting holes 13 evenly distributed along its circumference, wherein, for example... Figure 3 As shown, the axial depth of the roller limiting hole is h, and the axial thickness of the cage base is t1. The axial depth of each roller limiting hole 13 is between one-third and two-thirds of the axial thickness of the cage base.

[0040] In this embodiment, since the roller limiting hole does not penetrate the cage base in the axial direction, the cage base maintains a complete annular structure in the area not reached by the roller limiting hole. This ensures that the cage as a whole possesses the structural strength required for use. This type of cage structure allows for a more compact radial structure, making it particularly suitable for miniature planetary roller screw pairs.

[0041] Preferably, in this embodiment, the roller limiting hole 13 has openings, namely a first opening 131 provided on the outer periphery side of the cage base and a second opening 132 provided on the inner periphery side of the cage base. The widths of both the first opening 131 and the second opening 132 are smaller than the diameter of the roller limiting hole.

[0042] Of course, the provision of two openings in the roller limiting hole is only a preferred embodiment of this invention. Alternatively, only the first opening 131 or the second opening 132 may be provided, or no opening may be provided at all.

[0043] Preferably, in this embodiment, the connection between the roller limiting hole and the outer and inner peripheries of the cage is provided with rounded corners. The purpose of this is to prevent rubbing against other parts and to facilitate assembly.

[0044] As a special feature of this embodiment, the cage base 11 is further provided with two pin holes 14 evenly distributed along its circumference. The pin holes 14 extend radially from the outer circumferential surface of the cage base 11 to the central hole 12.

[0045] Of course, only two pin holes 14 are provided in this embodiment. In actual applications, the number of pin holes 14 can be set to more as needed.

[0046] A planetary roller screw pair using the cage of this embodiment, such as Figure 8 , Figure 9 As shown, it includes a nut 20, rollers 40, a lead screw 30, and a retainer 10 as shown in Embodiment 2. The plurality of rollers 40 are confined between the nut 20 and the lead screw 30 by a pair of opposing retainers 10.

[0047] In this embodiment, as Figure 8As shown, the roller 40 includes a threaded section 41, a gear-thread composite structure 42 located on both sides of the threaded section 41, and a smooth section 43 located outside the gear-thread composite structure 42. The smooth section 43 is located in the roller limiting hole 13 of the cage 10. The widths of the first opening 131 and the second opening 132 are smaller than the diameter of the smooth section 43. This ensures that the smooth sections 43 at both ends of the roller 40 cannot disengage from the first opening 131 and the second opening 132 in the radial direction.

[0048] Preferably, in this embodiment, the axial depth of the roller limiting hole 13 is greater than the length of the guide rod section 43. This arrangement provides sufficient axial space, ensuring proper axial movement of the roller and preventing jamming, while also facilitating assembly.

[0049] In this embodiment, the structure of the lead screw 30 is as follows: Figure 8 As shown, it includes a lead screw body 31, on which a lead screw thread section 32 is provided, and gears 33 are provided on both sides of the lead screw thread section 32. The gears 33 are used to mesh with the gears in the gear-thread composite structure 42 on the roller 40.

[0050] In this embodiment, a pin 50 is also included. The pin 50 is adapted to and installed in the pin hole 14, and the length of the pin 50 is greater than the length of the pin hole 14. When the pin 50 is installed in the pin hole 14, one end of it extending into the central hole 12 extends into the first annular groove 34, thereby realizing the assembly between the retainer 10 and the lead screw 30, and limiting the retainer in the axial direction.

[0051] In this embodiment, preferably, the pin 50 does not contact the bottom of the first annular groove 34 to reduce running friction.

[0052] In this embodiment, as a preferred option, such as Figure 10 As shown, a rolling element 52 is provided at one end of the pin 50 that is adapted to the first annular groove 34, and the rolling element 52 rolls and rubs against the first annular groove 34. The advantage of this arrangement is that it improves the radial support stability of the cage and reduces friction with the first annular groove. Preferably, in this embodiment, the end of the pin 50 is provided with a receiving groove 51, and the rolling element 52 is located in the receiving groove 51. Preferably, the rolling element is a ball.

[0053] Another planetary roller screw pair using the cage of this embodiment, such as Figures 11-12 As shown, the assembly includes a nut 20, rollers 40, a lead screw 30, and a retainer 10 as shown in Embodiment 1. The plurality of rollers 40 are positioned between the nut 20 and the lead screw 30 by a pair of opposing retainers 10.

[0054] In this embodiment, as Figure 11 As shown, the roller 40 includes a threaded section 41, a gear-thread composite structure 42 located on both sides of the threaded section 41, and a smooth section 43 located outside the gear-thread composite structure 42. The smooth section 43 is located in the roller limiting hole 13 of the cage 10. The widths of the first opening 131 and the second opening 132 are smaller than the diameter of the smooth section 43. This ensures that the smooth sections 43 at both ends of the roller 40 cannot disengage from the first opening 131 and the second opening 132 in the radial direction.

[0055] In this embodiment, the structure of the nut 20 is as follows: Figure 11 , Figure 12 As shown, it includes an internal thread section 21, an internal gear ring 22 located on both sides of the internal thread section 21, and a second annular groove 23 located on the outer side of the internal gear ring 22. The internal gear ring 22 meshes with the gear in the gear-thread composite structure 42 on the roller 40.

[0056] In this embodiment, as Figure 12 As shown, in the assembled state, the pin 50 is fixedly disposed in the pin hole 14. One end of the pin 50 does not protrude from the inner peripheral wall of the retainer base 11, while the other end of the pin 50 extends into the second annular groove 23 on the nut.

[0057] Preferably, pin 50 can also be set to Figure 10 The rolling element shown in the figure undergoes rolling friction with the second annular groove 23.

[0058] Example 3

[0059] One type of retainer 10 in this embodiment, such as Figure 13 , Figure 14 As shown, the difference between the retainer shown in Embodiment 2 and the retainer shown in Embodiment 3 lies in the structural arrangement of the pin hole 14.

[0060] Specifically, in this embodiment, the cage base 11 is provided with a pair of symmetrical pin holes 14. The two ends of the pin holes 14 penetrate the outer circumferential surface of the cage base 11. The axis of the pin holes 14 intersects the axis of the central hole 12 in a spatially perpendicular manner. Furthermore, the pin holes 14 partially intersect the central hole 12 in the radial direction.

[0061] A planetary roller screw pair using the cage of this embodiment, such as Figures 15-17 ,and Figures 2-4 ,as well as Figures 8-9 The difference in the planetary roller screw pair shown is that the cage 10 adopts the cage shown in Embodiment 3.

[0062] In this embodiment, as Figures 15-17As shown, it also includes a pin 50, which is adapted to and installed in the pin hole 14. Correspondingly, the lead screw 30 is provided with a first annular groove 34. When the pin 50 is installed in the pin hole 14, a portion of it extends radially inward into the first annular groove 34. With this arrangement, a portion of the pin 50 is located in the first annular groove 34, and a portion is located in the pin hole 14, thereby achieving the connection and limiting between the retainer and the lead screw.

[0063] In summary, the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A pin-fixed retainer, comprising an annular retainer base, the retainer base having a central hole, and the retainer base having a plurality of roller limiting holes evenly distributed along its circumference; characterized in that, The cage base is further provided with at least two pin holes distributed along its circumference; it also includes a pin, which is adapted to the pin holes and installed in the pin holes; when the pin is installed in the pin holes, a portion of it extends inward into the central hole.

2. The pin-fixed retainer according to claim 1, characterized in that, The pin hole extends radially from the outer circumferential surface of the retainer base to the central hole. The length of the pin is greater than the length of the pin hole. When the pin is installed in the pin hole, one end of it extends inward into the central hole.

3. The pin-fixed retainer according to claim 2, characterized in that, The pin holes are evenly distributed along the circumferential direction of the cage base.

4. The pin-fixed retainer according to claim 1, characterized in that, The axis of the pin hole intersects the axis of the center hole perpendicularly in space. Both ends of the pin hole penetrate the outer circumferential surface of the cage base. Furthermore, the pin hole partially intersects the center hole in the radial direction. When the pin is installed in the pin hole, a portion of it extends radially inward into the center hole.

5. The pin-fixed retainer according to claim 4, characterized in that, The pin holes are provided in two symmetrical positions.

6. A planetary roller screw assembly, comprising a nut, a lead screw, a plurality of rollers disposed between the nut and the lead screw, and a pair of cages for limiting the rollers; wherein each roller has a smooth section at both ends, the smooth section being received in a roller limiting hole of the cage; characterized in that, The retainer is a pin-fixed retainer as described in any one of claims 1-5, and the lead screw is provided with a first annular groove for accommodating the pin; when the pin is installed in the pin hole, the portion of the pin that extends into the central hole extends into the first annular groove.

7. A planetary roller screw assembly, comprising a nut, a lead screw, a plurality of rollers disposed between the nut and the lead screw, and a pair of cages for limiting the rollers; wherein each roller has a polished section at both ends, the polished section being received in a roller limiting hole of the cage; characterized in that, The retainer is a pin-fixed retainer as described in any one of claims 1-3, and the inner wall of the nut is provided with a second annular groove for accommodating the pin; when the pin is installed in the pin hole, the portion of it extending into the central hole extends into the second annular groove.

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