CN216842944U

CN216842944U - Planetary roller screw and transmission system thereof

Info

Publication number: CN216842944U
Application number: CN202120236718.6U
Authority: CN
Inventors: 李战训; 谢阳; 刘钊
Original assignee: Zhejiang Keboda Industrial Co ltd
Current assignee: Zhejiang Keboda Industrial Co ltd
Priority date: 2021-01-28
Filing date: 2021-01-28
Publication date: 2022-06-28
Anticipated expiration: 2031-01-28

Abstract

A planetary roller screw comprises a nut, a plurality of rollers, two retainers and a screw rod, wherein the rollers are uniformly distributed on the periphery of the screw rod along the circumferential direction and are all meshed with the screw rod, and two ends of each roller are respectively embedded into the two retainers; the nut is arranged at the periphery of the rollers and meshed with the rollers; wherein, each roller is respectively engaged with the screw rod and the nut in an interference manner. The utility model also discloses a planet roller lead screw transmission system of adopting above-mentioned planet roller lead screw. The utility model discloses a planet roller lead screw's precision is high, easily assembles.

Description

Planetary roller screw and transmission system thereof

Technical Field

The utility model relates to a planet roller screw technique.

Background

Roller screws, which translate the rotational motion of a motor into a linear reciprocating motion of a piston, are often used to control the disengagement and engagement of clutches. Fig. 1 shows a schematic view of a planetary roller screw for a friction clutch device. As shown in fig. 1, a conventional planetary roller screw 1a is mainly composed of a nut 11a, a plurality of rollers 12a, two holders 13a, a screw 14a, a housing 15a, and a bowl-shaped spring 16 a. Fig. 2 to 4 respectively show structural schematic diagrams of a bowl-shaped spring plate, a retainer and a roller of a conventional planetary roller screw.

In order to improve the running stability, the differential planetary roller screw needs to apply pretightening force to ensure normal movement, and enough friction force needs to be kept among all transmission parts. The bowl-shaped spring 16a provides a pre-load to eliminate the gap between the nut 11a and the roller 12a, but its accuracy gradually decreases with increasing load.

As shown in FIG. 3, the retainer 13a is provided with grooves 17a for limiting the rollers 12a, the journals 121a at both ends of the rollers 12a are axially positioned in the grooves 17a on the retainer, and the grooves 17a are open grooves, so that the journal 121a is not limited radially. In the actual assembly process, when the screw 14a is finally assembled, because the roller 12a cannot be radially limited, the roller 12a may be warped, that is, the axis of the roller 12a and the axis of the screw 14a have a certain angle, so that the screw 14a cannot be assembled smoothly, and therefore, a special tool clamp is required in the actual assembly process to keep the axis of the roller 12a parallel to the axis of the screw 14 a.

Fig. 5 shows a schematic structure of a conventional planetary roller screw transmission system applied to a clutch. As shown in fig. 5, the planetary roller screw transmission system includes a motor rotor 3a, a bearing 2a, and a roller screw 1 a. The motor rotor 3a, the bearing 2a and the roller screw 1a are axially arranged, the structure occupies large space, the structure of the whole actuator is increased, the space utilization rate is poor, and the requirement of compact system arrangement is not met. In addition, the size of the screw rod is very long, the rigidity of the system is reduced, only one bearing 2a in the system plays a main supporting role, the center of gravity of the system is far away from the center of the bearing 2a at the supporting point, the system can generate a swinging phenomenon in the moving process of the system, and the swinging amount of the planetary roller screw rod is gradually increased as the screw rod 14a is far away from the bearing 2 a.

Since the inner race of the bearing 2a is mounted on the screw 14a of the planetary roller screw 1a, the size of the bearing is limited. In the system, the bearing is the only stress point, all axial forces in the system are finally borne by the bearing 2a, the requirements of the motion stroke and the response time of the planetary roller screw in the system determine that the system can only select the deep groove ball bearing to meet the requirements, but the axial bearing capacity of the deep groove ball bearing is limited and is far lower than the axial force generated in the system, so that the type selection of the bearing 2a can only select a non-standard bearing, and the application of the non-standard bearing not only reduces the reliability of the system, but also improves the cost of the system.

Disclosure of Invention

The utility model aims to solve the technical problem that a planet roller lead screw that the precision is high, easily assemble is provided.

The utility model aims to solve still another technical problem and provide a planetary roller screw transmission system compact structure, system rigidity are strong, good reliability, with low costs.

The embodiment of the utility model provides a planet roller screw, including nut, a plurality of roller, two retainers and screw, a plurality of roller along the circumference evenly distributed in the periphery of screw, and all mesh with the screw, the both ends of each roller are embedded in two retainers respectively; the nut is arranged at the periphery of the rollers and meshed with the rollers; the nut is characterized in that each roller is respectively engaged with the screw rod and the nut in an interference manner.

The utility model discloses planet roller lead screw has following advantage at least: through the interference engagement of the roller and the screw rod and the nut, pretightening force can be generated under the condition of not additionally adopting a bowl-shaped elastic sheet, and the axial clearance between the roller and the screw rod and between the roller and the nut is eliminated, so that the precision of the planetary roller screw cannot change along with the change of the load, the overall precision of the roller screw is improved, and the assembly difficulty is reduced.

The embodiment of the utility model also provides a planetary roller screw transmission system, which comprises a motor rotor, a bearing and the planetary roller screw; the motor rotor and the bearing are respectively sleeved outside the nut of the planetary roller screw, and the nut can synchronously rotate along with the motor rotor.

The utility model discloses planetary roller screw drive system has following advantage at least:

1. the motor rotor and the bearing are radially arranged on the nut of the planetary roller screw, so that the whole structure of the transmission system is more compact, and the utilization rate of the system space is improved;

2. the bearing is arranged in the radial direction of the planetary roller screw, so that the gravity center of the system is closer to the support center, and the reliability of the system is improved;

3. the embodiment reduces the production difficulty and cost and prolongs the service life of the roller screw.

Drawings

Fig. 1 shows a schematic view of a planetary roller screw for a friction clutch device.

Fig. 2 to 4 respectively show structural schematic diagrams of a bowl-shaped spring plate, a retainer and a roller of a conventional planetary roller screw.

Figure 5 shows a resulting schematic of a prior art planetary roller screw drive system applied to a clutch.

Fig. 6 shows a schematic structural diagram of a planetary roller screw according to an embodiment of the invention.

Fig. 7 shows a schematic structural view of a cage of a planetary roller screw according to an embodiment of the present invention.

Fig. 8 shows a schematic structural diagram of a planetary roller screw drive system according to an embodiment of the invention.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

Fig. 6 shows a schematic structural diagram of a planetary roller screw according to an embodiment of the present invention, please refer to fig. 6. The planetary roller screw 1 according to an embodiment of the present invention includes a nut 11, a plurality of rollers 12, two cages 13, a screw 14, and two stopper members 16.

The plurality of rollers 12 are uniformly distributed on the periphery of the screw 14 along the circumferential direction and are in interference engagement with the screw 14, and two ends of each roller 12 are respectively embedded into the two retainers 13; the nut 11 is disposed on the outer periphery of the plurality of rollers 12 and is in interference engagement with the plurality of rollers 12.

In the present embodiment, each roller 12 includes a large diameter section 120, a first small diameter section 121, and a second small diameter section 122, the first small diameter section 121 and the second small diameter section 122 are respectively located at two sides of the large diameter section 120, the large diameter section 120 is in interference engagement with the lead screw 14, and the first small diameter section 121 and the second small diameter section 122 are respectively in interference engagement with the nut 11.

Further, the large diameter section 120 includes a plurality of large diameter section annular grooves 123 (lead angle is 0) for interference engagement with the thread (lead angle is not 0) of the lead screw 14, and the first small diameter section 121 and the second small diameter section 122 respectively include a plurality of small diameter section annular grooves 124 (lead angle is 0) for interference engagement with the plurality of annular convex teeth 114 (lead angle is 0) of the nut 11. Correspondingly, the first small diameter section 121 and the second small diameter section 122 also have a plurality of small diameter section annular convex teeth 125 (lead angle of 0) for interference engagement with the plurality of annular grooves 115 (lead angle of 0) of the nut 11.

Please refer to fig. 7. Each retainer 13 is annular, the annular retainer 13 is sleeved outside the screw 14, and the annular retainer 13 is provided with a plurality of mounting through holes 131 into which the plurality of rollers 12 are inserted in one-to-one correspondence. Two limiting parts 16 are respectively arranged on the outer sides of the two retainers 13 to limit the two retainers 13 from moving in the axial direction. In the present embodiment, the stopper member 16 is a retainer ring; the inner surface of the central hole of the nut 11 is provided with a stop step 116 that cooperates with the retainer ring 16, the stop step 116 abutting against the outer end surface of the retainer ring 16.

The shaft necks 127 at the two ends of the roller 12 are embedded into the mounting through holes 131 and are fixed in the nut 11 by the retaining rings 16 at the two ends, so that the axial limit and the radial limit of the roller 12 are realized, the axial line of the roller 12 and the axial line of the screw 14 are always kept parallel in the assembling process, and the warping phenomenon is avoided. In addition, in the assembling process, an additional tool is not needed for limiting the roller, so that the assembling process is simple.

The retaining rings 16 at the two ends only play a role of fixing, and do not generate axial pre-tightening force. In the embodiment, the size of the pitch diameter of the roller 12 is increased, so that the roller 12 is respectively in interference engagement with the screw 14 and the nut 11, and the contact area of the roller 12 with the nut 11 and the screw 14 is deformed to generate contact pressure to apply pre-tightening force (or the pitch diameter of the screw 14 is increased to achieve the purpose of pre-tightening). The interference fit of the middle diameter is used for replacing a bowl-shaped elastic sheet to generate pretightening force, and the precision of the planetary roller screw cannot change along with the change of the load in the actual operation process.

Fig. 8 shows a schematic structural diagram of a planetary roller screw drive system according to an embodiment of the invention. The planetary roller screw transmission system comprises a motor rotor 3, a bearing 2 and the planetary roller screw 1.

The motor rotor 3 and the bearing 2 are respectively sleeved outside the nut 11 of the planetary roller screw 1, and the nut 11 can rotate synchronously along with the motor rotor 3. The connection mode between the motor rotor 3 and the nut 11 can be key connection, interference fit and the like.

The motor rotor 3 and the bearing 2 are radially arranged on the nut 11 of the planetary roller screw 1, so that the structure is more compact, and the utilization rate of system space is improved. The screw 14 of the planetary roller screw does not need to be provided with a bearing, so that the length of the screw 14 is shortened, and the rigidity of the system is improved. Meanwhile, because the bearing 2 is arranged in the radial direction of the planet roller screw 1, the gravity center of the system is mainly concentrated on the planet roller screw 1, the gravity center is very close to the support center of the bearing 2, the swinging amount is very small and can be ignored, and therefore the reliability of the system is improved.

In addition, because the bearing 2 is arranged on the nut 11 of the planetary roller screw 1, the inner diameter of the bearing 2 is larger, and the axial force capable of being borne is correspondingly increased, so that under the condition of bearing the same axial force, a standard bearing can be selected to meet the requirement, the cost of the system is reduced, and the reliability of the system is improved.

It will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. A planetary roller screw comprises a nut, a plurality of rollers, two retainers and a screw rod, wherein the rollers are uniformly distributed on the periphery of the screw rod along the circumferential direction and are all meshed with the screw rod, and two ends of each roller are respectively embedded into the two retainers; the nut is arranged on the periphery of the plurality of rollers and meshed with the plurality of rollers; the nut is characterized in that each roller is respectively in interference engagement with the lead screw and the nut.

2. The planetary roller screw of claim 1, wherein each of the rollers includes a large diameter section, a first small diameter section, and a second small diameter section, the first small diameter section and the second small diameter section being respectively located on both sides of the large diameter section, the large diameter section being in interference engagement with the screw, and the first small diameter section and the second small diameter section being respectively in interference engagement with the nut.

3. A planetary roller screw according to claim 2, wherein the large diameter section includes a plurality of large diameter section annular grooves for interference engagement with the screw thread of the screw, and the first and second small diameter sections each include a plurality of small diameter section annular grooves for interference engagement with the plurality of annular lobes of the nut.

4. A planetary roller screw according to any one of claims 1 to 3, wherein each of the retainers is annular, the annular retainer is fitted around the screw, and the annular retainer is provided with a plurality of mounting through-holes into which the plurality of rollers are fitted in one-to-one correspondence.

5. The planetary roller screw of claim 4, comprising two limiting members respectively disposed outside the two cages to limit the axial movement of the two cages.

6. A planetary roller screw according to claim 5, wherein the limiting member is a retainer ring; the inner surface of the central hole of the nut is provided with a stopping step matched with the retainer ring, and the stopping step is abutted to the outer end face of the retainer ring.

7. A planetary roller screw drive system comprising a motor rotor, a bearing and a planetary roller screw according to any one of claims 1 to 6;

the motor rotor and the bearing are respectively sleeved outside the nut of the planetary roller screw, and the nut can rotate synchronously along with the motor rotor.