Circulating type planetary roller lead screw pair

Abstract

The utility model relates to the technical field of high-precision transmission, in particular to a circulating type planetary roller lead screw pair, which at least comprises a lead screw, a nut, a retainer, a roller and an end face cam, the retainer comprises a circular ring-shaped main body, the circular ring-shaped main body is provided with an inner hole for the lead screw to penetrate through, and the end face cam is arranged in the inner hole. A plurality of roller guide grooves which are uniformly distributed in the circumferential direction are formed in the circular ring-shaped main body, the roller guide grooves extend in the radial direction of the circular ring-shaped main body, and the retainers are symmetrically mounted on the two sides of the internal thread section; a plurality of pin rollers are arranged between the lead screw and the nut; and two ends of each pin roller are positioned in the pin roller guide grooves of the retainer. According to the structure, the retainers are in a circular ring shape and are arranged on the two sides of the internal thread section of the nut, so that the overall radial size of the circulating type planetary roller screw pair can be reduced, and a reliable structural foundation is provided for achieving miniaturization and microminiaturization of the circulating type planetary roller screw pair.

Description

Technical Field

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

[0002] Circulating planetary roller screw pairs are widely used in high-performance transmission applications such as robots, spacecraft, and precision machine tools to achieve high-load, high-precision linear motion. Their core principle is that multiple rollers circulate within the threaded channel between the screw and nut, achieving high transmission efficiency, high rigidity, and backlash-free transmission.

[0003] As the roller rolls within the threaded channel, axial relative displacement occurs due to the discrepancy between its helix angle and that of the nut. Each time the roller completes one revolution, it moves one lead relative to the leadscrew axially. To achieve cyclic motion, when the roller reaches the notch area of ​​the nut, the end face cams located at both ends of the nut apply an axial thrust to the roller. Under this action, the roller rises along the thread angle direction, thus bypassing the major diameter section of the leadscrew and completing its stroke reset, re-entering the threaded channel to continue its journey. In this process, the cage plays a crucial guiding and positioning role. On one hand, the cage ensures that each roller is in the accurate position, preventing interference or misalignment; on the other hand, the cage maintains proper contact with the roller, helping to guide the roller smoothly through the process of disengaging from and returning to the threaded track.

[0004] Traditional recirculating planetary roller screw assemblies are described in the industry standard "T / TCMCA 0026-2023" entitled "Planetary Roller Screw Assemblies". The cage is a squirrel-cage type, located between the screw and the rollers, and is divided into three sections: a central support section and two side clearance sections. The support section needs sufficient thickness to guide the rollers smoothly out of and back into the threaded channel; while the clearance sections must be extremely thin to avoid interference with the end face cam during reversal. This highly demanding structure with precise thickness control is difficult to manufacture in miniature screw assemblies, especially when overall dimensions are limited. The rigidity of the support section is difficult to guarantee, while the clearance sections are prone to deformation, severely limiting overall durability and structural reliability.

[0005] However, in some existing application scenarios, especially in the field of robotics, the demand for miniaturization and micro-miniaturization of cyclic planetary roller screw pairs is gradually increasing, while the squirrel cage cage in traditional cyclic planetary roller screw pairs limits the development of miniaturization and micro-miniaturization of cyclic planetary roller screw pairs.

[0006] Furthermore, in traditional recirculating planetary roller screw assemblies, an end-face cam applies axial force to the rollers, forcibly lifting them along the thread angle to achieve disengagement and re-entry from the thread. Although this structure achieves synchronous linkage between the screw and the nut, the rollers must be forced to cross the thread crest during reversal, and the intense contact between the rollers and the metal surface causes severe friction between the rollers and the thread crest, resulting in significant noise and thread wear problems. Summary of the Invention

[0007] The technical problem to be solved by this utility model is to provide a circulating roller screw pair that is conducive to miniaturization and micro-miniaturization, so as to overcome the technical defects of existing circulating roller screw pairs that are difficult to miniaturize and micro-miniaturize.

[0008] To solve the above-mentioned technical problems, the technical solution provided by this utility model is as follows: A cyclic planetary roller screw pair, comprising at least:

[0009] A lead screw, wherein the lead screw is provided with an external thread;

[0010] The nut has an internal thread section inside, and the inner wall of the nut has an axially extending clearance groove that passes through the internal thread section.

[0011] A retainer, comprising an annular body having an inner hole for accommodating a lead screw, and having a plurality of roller guide grooves evenly distributed along the circumference of the annular body extending along the radial direction of the annular body; the retainer is symmetrically mounted on both sides of the internal thread section.

[0012] Rollers, multiple rollers are disposed between the lead screw and the nut, with both ends of the rollers located in the roller guide grooves of the cage;

[0013] An end face cam is provided on the outer side of the cage, and a protrusion is provided on the side of the end face cam facing the roller.

[0014] In a preferred embodiment, the roller includes a threaded section and smooth sections located at both ends of the threaded section, the smooth sections of the roller cooperating with the roller guide groove; or, the roller includes only the threaded section, the two ends of the threaded section cooperating with the roller guide groove.

[0015] In a preferred embodiment, the inner radial end of the roller guide groove is provided with an opening that extends through to the inner hole of the annular body.

[0016] In a preferred embodiment, the two sides of the opening contract inward to form a contraction opening, and the contraction opening is elastic.

[0017] In a preferred embodiment, the material of the annular body is elastic, and the constriction opening is based on the elasticity of the material of the annular body.

[0018] In a preferred embodiment, a perforated groove extending through to the inner hole of the annular body is provided between adjacent roller guide grooves, and elastic arms are formed on both sides of the perforated groove, forming elastic contraction openings on both sides of the roller guide groove.

[0019] In a preferred embodiment, elastic arms protruding from the inner wall of the annular main body are provided on both sides of the roller guide groove, and a contraction opening is formed between adjacent elastic arms.

[0020] In a preferred embodiment, when the roller and nut are in the internal thread engagement state, the roller is elastically clamped by the contraction opening of the roller guide groove and driven to elastically deform outward. When the roller runs to the clearance groove position, the roller is driven to enter the clearance groove radially based on the elastic reset of the contraction opening.

[0021] In a preferred embodiment, the cage is provided with a radial cut-off notch.

[0022] In a preferred embodiment, the nut is provided with a slot for accommodating the cage.

[0023] The cage and recirculating planetary roller screw assembly of this embodiment have the following advantages compared with the prior art:

[0024] (1) Compared with the traditional cage structure located between the roller and the screw, the circular cage is set on both sides of the internal thread section of the nut. This can reduce the overall radial dimension of the recirculating planetary roller screw pair and provide a reliable structural basis for the miniaturization and micro-miniaturization of the recirculating planetary roller screw pair.

[0025] (2) The planar cage structure is convenient for CNC milling or stamping and other processing methods, replacing the traditional squirrel cage structure, greatly simplifying the production process, resulting in higher production efficiency and lower cost.

[0026] (3) The roller guide groove on the cage is provided with an opening that extends through the inner hole of the annular body, so that the radial dimension of the cage can be made smaller, and thus the overall radial dimension of the circulating planetary roller screw pair is smaller, which can make the circulating planetary roller screw pair more miniaturized and micro-sized.

[0027] (4) The opening of the roller guide groove on the retainer is set as an elastic contraction opening. When the roller needs to be axially reset when it runs to the position of the relief groove, the elastic reset of the contraction opening drives the roller to enter the relief groove radially. When it passes the crest of the external thread on the screw, it drives the roller to reset, making the roller reset smoother. This effectively reduces the friction between the roller and the external thread on the screw, effectively avoids impact noise, and extends the service life of the screw and roller.

[0028] (5) The cage design has excellent guiding characteristics, making the rollers run more stably and the system has stronger dynamic response. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the exploded state structure of the cyclic planetary roller screw pair shown in Example 1.

[0030] Figure 2 This is a schematic diagram of the longitudinal section of the cyclic planetary roller screw pair shown in Example 1.

[0031] Figure 3 This is a schematic diagram of the cage structure in the first embodiment of the cyclic planetary roller screw pair shown in Example 1.

[0032] Figure 4 This is a schematic diagram of the cage structure in the second embodiment of the cyclic planetary roller screw pair shown in Example 1.

[0033] Figure 5 This is a schematic diagram of the cage structure in the third embodiment of the cyclic planetary roller screw pair shown in Example 1.

[0034] Figure 6 This is a schematic diagram of the cage structure in the fourth embodiment of the cyclic planetary roller screw pair shown in Example 1.

[0035] Figure 7 for Figure 6 A schematic diagram of the three-dimensional structure of the cage shown;

[0036] Figure 8 This is a schematic diagram of the cage structure in the fifth embodiment of the cyclic planetary roller screw pair shown in Example 1.

[0037] Figure 9 This is a schematic diagram of the nut structure in the cyclic planetary roller screw pair shown in Example 1;

[0038] Figure 10 This is a cross-sectional view of the cyclic planetary roller screw pair shown in Example 1.

[0039] Figure 11 This is a schematic diagram of the planar structure of the cage in the cyclic planetary roller screw pair shown in Embodiment 2;

[0040] Figure 12 This is a schematic diagram of the longitudinal section of the cyclic planetary roller screw pair shown in Example 2. Detailed Implementation

[0041] 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.

[0042] 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.

[0043] 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.

[0044] Example 1,

[0045] This embodiment describes a type of cyclic planetary roller screw pair, such as... Figure 1 , Figure 2 and Figure 9 As shown, the assembly includes a lead screw 50, a nut 20, a roller 30, an end face cam 40, and a cage 10. The lead screw 50 has external threads, and the nut 20 has an internal thread section 21 and mounting sections 22 located on both sides of the internal thread section. The mounting sections 22 are used to mount the cage 10 and the end face cam 40. The inner wall of the nut 20 has an axially extending clearance groove 23 that penetrates the internal thread section 21. The roller 30 achieves axial reset at the location of the clearance groove 23 based on the protrusion 41 on the end face cam 40. It should be noted that the above structures are mature structures of circulating planetary roller lead screw pairs in this field, and their specific structures will not be described in detail in this embodiment.

[0046] As a special feature of this embodiment, the retainer 10 in this embodiment is as follows: Figures 3-8 As shown, it includes an annular body 11 with an inner hole 12. The annular body 11 is provided with a plurality of roller guide grooves 13 evenly distributed along the circumference. The roller guide grooves 13 extend along the radial direction of the annular body 11, allowing the rollers 30 to achieve radial displacement within the roller guide grooves 13.

[0047] In this embodiment, the roller 30 includes a threaded section 31 and smooth sections 32 located at both ends of the threaded section. The smooth sections 32 of the roller 30 cooperate with the roller guide groove 13. Of course, this is only a preferred embodiment of this embodiment. As an equivalent embodiment, the roller may only include the threaded section without the smooth sections, and the two ends of the threaded section cooperate with the roller guide groove 13.

[0048] The structure of the cage 10 in the first preferred embodiment of this example is as follows: Figure 3 As shown, its roller guide groove 13 does not extend into the inner hole 12.

[0049] The structure of the cage 10 in the second preferred embodiment of this example is as follows: Figure 4 As shown, the roller guide groove 13 has an opening at its radially inner end that extends through to the inner hole 12 of the annular body 11. This embodiment is similar to... Figure 3 Compared to the structure of the cage shown, the radial dimension of the cage can be made smaller because the wall between the roller guide groove 13 and the inner hole 12 is reduced in the radial direction. This results in a smaller overall radial dimension of the recirculating planetary roller screw pair, making the recirculating planetary roller screw pair more miniaturized and micro-sized.

[0050] The structure of the cage 10 in the third preferred embodiment of this example is as follows: Figure 5 As shown, in Figure 4 Based on the structure of the cage shown, the two sides of the opening are narrowed inward to form a contraction opening 16. Furthermore, this contraction opening 16 is elastic. In this embodiment, the material of the annular body is elastic, and the contraction opening is based on the elasticity of the material of the annular body.

[0051] In this embodiment, such as Figure 10 As shown, when the roller 30 and nut 20 are in the internal thread engagement state, the roller 30 is elastically clamped by the contraction opening 16 of the roller guide groove 13 and driven to elastically deform outward. When the roller 30 runs to the position of the clearance groove 23, as... Figure 10 As shown at point A, the elastic reset mechanism of the contraction opening 16 drives the roller 30 radially into the clearance groove 23. In this state, the roller achieves axial reset under the action of the protrusion 41 on the end face cam 40. The cage of this embodiment, and... Figures 3-4 Compared to the cage shown, during the axial reset of the rollers, the rollers pass over the crest of the external thread of the lead screw, making the roller reset smoother. This effectively reduces the friction between the rollers and the external thread of the lead screw, effectively avoids impact noise, and extends the service life of the lead screw and rollers.

[0052] Preferably, in this embodiment, the inner side of the contraction opening 16 is provided with an inner arc-shaped portion 18 for contacting and engaging with the roller, so that the contraction opening 16 has better wrapping effect on the roller 30 and drives the roller to move radially more smoothly.

[0053] The structure of the cage 10 in the fourth preferred embodiment of this example is as follows: Figures 6-7 As shown, in Figure 5 Based on the structure of the cage shown, a perforated groove 17 extending through to the inner hole 12 of the annular body is provided between adjacent roller guide grooves 13. Elastic arms 15 are formed on both sides of the perforated groove 17, and the elastic arms on both sides of the roller guide groove 13 form elastic contraction openings 16. The perforated groove 17 serves the dual purpose of reducing weight and increasing the elasticity of the elastic arms.

[0054] The structure of the cage 10 in the fifth preferred embodiment of this example is as follows: Figure 8 As shown, elastic arms 15 protruding from the inner wall of the annular main body inner hole 12 are provided on both sides of the roller guide groove 13, and an elastic contraction opening 16 is formed between adjacent elastic arms.

[0055] In this embodiment, the cage material can be selected from different materials such as metal, engineering plastics, and resin to adapt to diverse application scenarios.

[0056] In this embodiment, since the cage has a planar structure, it is easy to perform CNC milling or stamping processing, replacing the traditional squirrel cage structure, which greatly simplifies the production process, resulting in higher production efficiency and lower costs.

[0057] In this embodiment, a pair of retainers 10 are provided and are disposed opposite to each other on both sides of the internal thread section 21, and the end face cam is disposed on the outer side of the retainer. It should be noted that this is only a preferred embodiment of this embodiment. In practical applications, the position of the retainer is not limited to both ends, and it can also be disposed on one side or in the middle of a double nut structure.

[0058] Example 2,

[0059] This embodiment describes a type of cyclic planetary roller screw pair, such as... Figure 11 , Figure 12 As shown, the difference from Embodiment 1 is that the retainer 10 is provided with a radial cut-off 19, giving the retainer 10 elastic deformation capability. Accordingly, as Figure 10 As shown, the nut 20 has a slot 24 for accommodating the retainer 10.

[0060] It should be noted that, in this embodiment, Figure 11 The cage shown is based on Figure 6 , Figure 7The cage shown is provided with a radial cut-off notch 19. It should be understood that... Figures 3-5 as well as Figure 8 The cage shown can also be provided with a radial cut-off 19.

[0061] During assembly, based on the design of the radial cut-off opening 19, the cage 10 is first radially compressed and then placed in the slot 24. After release, the cage is installed in the slot 24 based on the elastic restoring force. This structure enables reliable fixation and safe operation of the cage in a small space. Its advantages are that the range of motion of the cage in the axial direction is limited within the annular groove, avoiding axial drift or accidental dislodgement of the cage during operation; ensuring that the cage is always located in the working area corresponding to the roller, ensuring the continuity of roller cyclic guidance; reducing the risk of direct contact between the cage and structures such as the end face cam, improving the structural fault tolerance of the system; and optimizing the assembly process, making cage installation faster and more accurate, and improving maintenance convenience.

[0062] 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 circulating planetary roller screw pair, characterized in that, At least including: A lead screw, wherein the lead screw is provided with an external thread; The nut has an internal thread section inside, and the inner wall of the nut has an axially extending clearance groove that passes through the internal thread section. A retainer, comprising an annular body having an inner hole for accommodating a lead screw, and having a plurality of roller guide grooves evenly distributed along the circumference of the annular body extending along the radial direction of the annular body; the retainer is symmetrically mounted on both sides of the internal thread section. Rollers, multiple rollers are disposed between the lead screw and the nut, with both ends of the rollers located in the roller guide grooves of the cage; An end face cam is provided on the outer side of the cage, and a protrusion is provided on the side of the end face cam facing the roller.

2. The cyclic planetary roller screw pair according to claim 1, characterized in that, The roller includes a threaded section and smooth sections located at both ends of the threaded section, the smooth sections of the roller cooperating with the roller guide groove; or, the roller only includes a threaded section, the two ends of the threaded section cooperating with the roller guide groove.

3. The cyclic planetary roller screw pair according to claim 2, characterized in that, The roller guide groove has an opening at its radial inner end that extends through to the inner hole of the annular body.

4. The cyclic planetary roller screw assembly according to claim 3, characterized in that, The two sides of the opening contract inward to form a contraction opening, and the contraction opening is elastic.

5. The cyclic planetary roller screw pair according to claim 4, characterized in that, The material of the annular body is elastic, and the contraction opening is based on the elastic material of the annular body.

6. The cyclic planetary roller screw pair according to claim 4, characterized in that, A perforated groove is provided between adjacent roller guide grooves, extending through to the inner hole of the annular body. Elastic arms are formed on both sides of the perforated groove, and the elastic arms on both sides of the roller guide groove form elastic contraction openings.

7. The cyclic planetary roller screw pair according to claim 4, characterized in that, The roller guide groove has elastic arms protruding from the inner wall of the annular main body on both sides, and a contraction opening is formed between adjacent elastic arms.

8. The cyclic planetary roller screw assembly according to any one of claims 4-7, characterized in that, When the roller and nut are in the internal thread engagement state, the roller is elastically clamped by the contraction opening of the roller guide groove and driven to elastically deform outward. When the roller runs to the clearance groove position, the roller is driven to enter the clearance groove radially based on the elastic reset of the contraction opening.

9. The cyclic planetary roller screw assembly according to any one of claims 1-7, characterized in that, The cage is provided with a radial cut-off.

10. The cyclic planetary roller screw assembly according to claim 9, characterized in that, The nut has a slot for accommodating the cage.

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