Planetary roller screw
Through the planetary roller screw structure, the problem of volume and cost increase in traditional screw transmission with small stroke and large thrust is solved, and small lead and large thrust and high-efficiency transmission is achieved.
Patent Information
- Application Number
- CN202421910394.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-08
- Publication Date
- 2025-07-08
- Estimated Expiration
- 2034-08-08
AI Technical Summary
In the prior art, when a screw transmission requires a small stroke and large thrust, the traditional method increases the reduction mechanism resulting in an increase in volume and weight, and is highly manufactured.
The planetary roller screw structure is adopted, and the effect of small lead and large thrust is achieved through the composite movement of the lead screw, roller and nut, and rolling friction transmission is used to improve transmission efficiency and load bearing capacity.
It realizes small lead and large thrust, simplifies the structure, cancels the speed reduction mechanism, and improves the transmission efficiency and load bearing capacity.
Smart Images
Figure CN223076150U_ABST
Abstract
Description
Technical Field
[0001] This application relates to screw drive technology, and particularly to a planetary roller screw. Background Art
[0002] Screw drive is the most important mechanism for converting rotary motion into linear motion and is widely used. In many applications, a small stroke but a large thrust is required, such as the clamping actuator in an electromechanical brake. Since the lead of the screw is physically difficult to make too small and the input power is limited, the traditional method is to increase the reduction mechanism at its input end to achieve the goal of increasing the output linear force. This will inevitably increase the volume and weight and also increase the manufacturing cost. Utility Model Content
[0003] In view of the above problems, this application aims to propose a planetary roller screw, which can achieve the effect of a theoretically very small actual lead while having a large physical lead.
[0004] This application proposes a planetary roller screw, which includes a screw, rollers, and a nut; the screw is located at the central position of the nut, there are multiple rollers, which are arranged along the circumferential surface of the screw between the nut and the screw; the screw, rollers, and nut form a structure of a composite motion of left planetary motion and spatial spiral motion;
[0005] The rollers are of a hollow structure, and a spline shaft passes through them; the spline shaft rotates together with the rollers; first gears coaxial with it are respectively installed at both ends of the spline shaft;
[0006] Second gears are respectively arranged at both ends of the screw;
[0007] The first gears at both ends of the rollers are correspondingly meshed with the second gears at both ends of the screw;
[0008] The first gears at both ends of the rollers rotate together with the rollers and the corresponding spline shaft, and there is no axial movement relative to the screw.
[0009] This application also proposes a planetary roller screw, which includes a screw, rollers, and a nut; the screw is located at the central position of the nut, there are multiple rollers, which are arranged along the circumferential surface of the screw between the nut and the screw; the screw, rollers, and nut form a structure of a composite motion of left planetary motion and spatial spiral motion;
[0010] The rollers are of a hollow structure, and a spline shaft passes through them; the spline shaft rotates together with the rollers; first gears coaxial with it are respectively installed at both ends of the spline shaft;
[0011] Internal gears are respectively arranged on the inner circumferential surfaces at both ends of the nut, and the internal gears are coaxial with the nut;
[0012] The first gears at both ends of the rollers are correspondingly meshed with the internal gears at both ends of the nut;
[0013] The first gears at both ends of the roller rotate together with the roller and the corresponding spline shaft, and there is no axial movement relative to the lead screw.
[0014] Preferably, the second gears at both ends of the lead screw are integrally formed with the lead screw.
[0015] Preferably, the second gears at both ends of the lead screw are discrete from the lead screw.
[0016] Preferably, the lead screw or the nut is the driving member.
[0017] Preferably, both ends of the plurality of rollers arranged around the lead screw are respectively indexed and positioned by end rings.
[0018] The planetary roller screw of the present application can achieve an infinitely small actual lead in theory while having a relatively large physical lead. At the same time, it is a rolling friction drive with a relatively high screw drive efficiency; and due to the adoption of the basic structure of the planetary roller screw, it has a relatively large load-bearing capacity. Brief Description of the Drawings
[0019] Figure 1 is a schematic diagram of the structure and composition of the planetary roller screw of the present application;
[0020] Figure 2 is Figure 1 a schematic diagram of the split composition of the planetary roller screw of
[0021] Figure 3 is a schematic diagram of the gear and lead screw integrated structure of the planetary roller screw of the present application;
[0022] Figure 4 is a schematic diagram of the structure in which the internal gear of the planetary roller screw of the present application is installed on the nut. Detailed Description of the Invention
[0023] The planetary roller screw of the present application is characterized in that its structural composition and motion relationship are similar to those of the circulating planetary roller screw, that is, it is composed of three main components: a lead screw, rollers, and a nut. The rollers follow both the planetary motion relationship with the lead screw and the nut, and at the same time have the characteristic that the rollers move axially relative to the lead screw and the nut. The difference is that the rollers do not need to circulate, and the planetary motion of the rollers and the lead screw is ensured by mutually meshing gears. The center of the roller passes through a spline shaft, and the spline shaft is fixed to the gears at both ends and rotates simultaneously with the rollers, but allows the rollers to move axially. A plurality of rollers arranged along the circumferential direction of the lead screw are indexed by end rings to ensure their correct distribution positions. The distribution holes on the end rings pass through the central shaft and allow the central shaft to rotate freely.
[0024] Generally, the nut and the lead screw are multi-start threads, and the rollers are provided with annular grooves. The groove pitch of the annular grooves is the same as the pitch of the threads.
[0025] The angular velocity of the lead screw is ω. When it rotates one week, the moving distance of the roller relative to the lead screw is L1, and the moving distance relative to the nut is L2. The relative displacement between the two is the displacement of the lead screw relative to the nut - that is, the lead s.
[0026] Limited by the component size, this mechanism is only applicable to small stroke cases.
[0027] The implementation mode of the planetary roller screw of the present application is shown in the attached drawings of the specification.
[0028] Figure 1 In the figure, the planetary roller screw of the present application mainly includes: nut 1, roller 2, and lead screw 3. The pitch diameter of the internal thread of nut 1, the pitch diameter of the teeth of roller 2, and the pitch diameter of the thread of lead screw 3 constitute the planetary motion elements around the pitch diameter circle of lead screw 3. That is, if nut 1 does not make a rotational motion and lead screw 3 makes a rotational motion, then roller 2 makes a revolution and a rotation around the center of lead screw 3.
[0029] To ensure the correct realization of this motion, in addition to the correct structural dimensions, gears 22 and 31 that conform to the meshing transmission law are provided at the ends of lead screw 3 and roller 2. The axis of gear 22 is coaxial with roller 2, and the axis of gear 31 is coaxial with lead screw 3. Roller 2 is hollow, and a spline shaft 21 passes through its interior and forms a sliding fit relationship with spline shaft 21. The fit between the hollow roller 2 and spline shaft 21 can be achieved through a structure 23 fixed at the end. Structure 23 realizes a sliding fit with spline shaft 21, but it is only a part of roller 2. It must be coaxial with roller 2. The other hollow parts of roller 2 can be through holes that allow spline shaft 21 to pass through freely. A number of rollers 2 are distributed along the circumferential direction of lead screw 3 and are indexed and positioned by an end ring 4. The end ring 4 is axially positioned by a circlip 41. Similarly, the gears on spline shaft 21 are also positioned by circlips, and the middle hole of gear 22 forms a tight fit with spline shaft 21.
[0030] Structurally, the gear 31 at the end of lead screw 3 can be separated from the lead screw 3 body and fastened by means such as screws, such as Figure 1 or it can be an integral structure form, such as Figure 3 .
[0031] In the present application Figure 1 In the shown embodiment, the driving part is lead screw 3. In other embodiments of the present application, the driving part can also be nut 1. As long as there is a relative rotation between nut 1 and lead screw 3.
[0032] In the present application Figure 1In the illustrated embodiment, the roller 2 meshes with the gear at the end of the lead screw 3. In other embodiments, it may also be that the roller 2 meshes with the gear at the end of the nut 1; the gear at the end of the lead screw 3 is cancelled and replaced by an internal gear mounted at the end of the nut. The internal gear is coaxial with the nut 1 and meshes correctly with the gear at the end of the roller 2, and conforms to the planetary motion law, such as Figure 4 , an internal gear 11 is formed on the nut 1.
[0033] Advantages
[0034] 1. Small lead, that is, a rolling lead screw with a very small lead can be manufactured, which is beneficial to simplifying the structure of the working device constituted by it. Because a small lead means a small driving torque, the reduction mechanism can often be cancelled.
[0035] 2. No slipping, constant ratio transmission. For the planetary roller screw of the present application, the transmission of the lead screw has a strict input-output speed ratio relationship and no slipping phenomenon will occur.
[0036] Unless otherwise defined, all technical and / or scientific terms used in this application have the same meaning as commonly understood by those of ordinary skill in the field to which this application pertains. The materials, methods, and examples mentioned in this application are illustrative only and not restrictive.
[0037] Although the present application has been described in conjunction with specific embodiments, under the inventive concept of the present application, those skilled in the art can make appropriate substitutions, modifications, and changes, and such substitutions, modifications, and changes still fall within the protection scope of the present application.
Claims
1. A planetary roller screw, comprising a screw rod, rollers, and a nut; the screw rod is located at the central position of the nut, there are multiple rollers, which are arranged between the nut and the screw rod along the circumferential surface of the screw rod; the screw rod, rollers, and nut form a structure of compound motion of left planetary motion and spatial spiral motion; it is characterized in that: The rollers are of a hollow structure, through which a spline shaft passes; the spline shaft rotates together with the rollers; first gears coaxial with it are respectively installed at both ends of the spline shaft; Second gears are respectively arranged at both ends of the screw rod; The first gears at both ends of the rollers are correspondingly meshed with the second gears at both ends of the screw rod; The first gears at both ends of the rollers rotate together with the rollers and the corresponding spline shaft, and have no axial movement relative to the screw rod.
2. The planetary roller screw according to claim 1, characterized in that: The second gears at both ends of the screw rod are integrally formed with the screw rod.
3. The planetary roller screw according to claim 1, characterized in that: The second gears at both ends of the screw rod are discrete from the screw rod.
4. The planetary roller screw according to claim 1, characterized in that: The screw rod or the nut is the driving part.
5. The planetary roller screw according to claim 1, characterized in that: Both ends of the multiple rollers arranged around the screw rod are respectively indexed and positioned through end rings.
6. A planetary roller screw, comprising a screw rod, rollers, and a nut; the screw rod is located at the central position of the nut, there are multiple rollers, which are arranged between the nut and the screw rod along the circumferential surface of the screw rod; the screw rod, rollers, and nut form a structure of compound motion of left planetary motion and spatial spiral motion; it is characterized in that: The rollers are of a hollow structure, through which a spline shaft passes; the spline shaft rotates together with the rollers; first gears coaxial with it are respectively installed at both ends of the spline shaft; Internal gears are respectively arranged on the inner circumferential surfaces at both ends of the nut, and the internal gears are coaxial with the nut; The first gears at both ends of the rollers are correspondingly meshed with the internal gears at both ends of the nut; The first gears at both ends of the rollers rotate together with the rollers and the corresponding spline shaft, and have no axial movement relative to the screw rod.
7. The planetary roller screw according to claim 6, characterized in that: The second gears at both ends of the screw rod are integrally formed with the screw rod.
8. The planetary roller screw according to claim 6, characterized in that: The second gears at both ends of the screw rod are discrete from the screw rod.
9. The planetary roller screw according to claim 6, characterized in that: The screw rod or the nut is the driving part.
10. The planetary roller screw according to claim 6, characterized in that: Both ends of the multiple rollers arranged around the screw rod are respectively indexed and positioned through end rings.