High-precision integrated planetary roller screw rod device

Abstract

The invention discloses a high-precision integrated planetary roller lead screw device, and belongs to the field of transmission mechanisms. A step cavity is formed in the main case; the motor stator is fixedly connected to the middle side wall of the step cavity; the right side wall of the step cavity is connected with a bearing outer ring; the bearing outer ring is in interference fit or transition fit connection with the right side wall of the step cavity; the outer side of the left side of the planetary roller screw rod inner gear ring shaft is rigidly connected with magnetic steel; an encoder is fixedly arranged on the left side wall of the step cavity; a lead screw through internal thread is arranged on the inner side of the planetary roller lead screw inner gear ring shaft, a lead screw is arranged in the step cavity and coincides with the axis of the step cavity, the left side of the lead screw is in interference connection with a roller retainer, the right end of the roller retainer is rotationally connected with a plurality of rollers, and the lead screw through internal thread is in threaded connection with the rollers. According to the planetary roller screw rod driving device, an original motor driving component and a planetary roller screw rod are integrated, and the size of the device is reduced.

Description

Technical Field

[0001] This application relates to the field of transmission mechanisms, and more specifically, to a high-precision integrated planetary roller screw device. Background Technology

[0002] Traditional planetary roller screw transmission mechanisms mostly adopt a split design, requiring a coupling or reducer to connect the motor to the planetary roller screw, resulting in a long transmission chain and large size (e.g., the joint module of an industrial robot can reach a volume of 120cm²). 3 This leads to reduced accuracy during later installation, especially worsening of coaxiality, resulting in transmission efficiency of less than 75%. Summary of the Invention

[0003] The summary section of this application is intended to provide a brief overview of the concepts, which will be described in detail in the detailed description section below. This summary section is not intended to identify key or essential features of the claimed technical solutions, nor is it intended to limit the scope of the claimed technical solutions.

[0004] To address the technical problems mentioned in the background section, some embodiments of this application provide a high-precision integrated planetary roller screw device, comprising: a housing; a stator inside the housing; a motor stator fixed inside the housing; a bearing outer ring inside the housing; the bearing outer ring being interference-fitted or transition-fitted with the inner side of the housing; the inner side of the bearing outer ring contacting rolling elements; a first row of outer ring raceways on the inner side of the bearing outer ring, the first row of outer ring raceways contacting the first row of rolling elements; the first row of rolling elements contacting the first row of inner ring raceways, the first row of inner ring raceways located on the outer surface of the planetary roller screw internal gear ring shaft; a second row of outer ring raceways on the inner side of the bearing outer ring, the second row of outer ring raceways contacting the second row of rolling elements; the second row of rolling elements contacting the second row of inner ring raceways, the second row of inner ring raceways located on the outer surface of the planetary roller screw internal gear ring shaft; one side of the outer surface of the planetary roller screw internal gear ring shaft being integrated with a magnet to form the rotor shaft of the entire device. Preferably, an encoder is fixedly installed on the left inner side of the housing; the inner diameter of the encoder is larger than the rotor shaft of the device, so it does not interfere with the rotor shaft; the inner side of the rotor shaft is connected to the roller; there is a roller retainer on the side of the roller; the roller is also connected to the lead screw; the roller is connected to the internal gear ring shaft of the planetary roller lead screw and the lead screw by threads; the mechanical and electrical structures of this invention both adopt a cantilever support structure, which can reduce the size of the device and increase the power density. Furthermore, the planetary roller lead screw structure, rolling bearings, and magnets are integrated into one unit, cleverly reducing the size of the entire device. Moreover, there is no need for couplings or reducers to connect the drive and the planetary roller lead screw, reducing losses during transmission. It can also improve the coaxiality between the motor and the roller lead screw, and improve the lead screw accuracy.

[0005] Preferably, the present invention has a first motor end cover on the left side of the outer casing and a second motor end cover on the right side of the outer casing. The inner side of the second motor end cover contacts and limits the bearing end face. The inner side of the second motor end cover has a felt oil seal, and the felt oil seal forms a small gap with the lead screw. This improves the sealing performance of the entire planetary roller lead screw device without affecting rotation.

[0006] Priority is given to the sealing caps between the outer ring of the bearing and the inner gear ring of the planetary roller screw, as well as on both sides of the two rows of rolling elements, to enhance the sealing of the bearing.

[0007] Preferably, the contact angle formed by the straight line connecting the rolling element and the outer raceway of the bearing and the inner raceway of the rotor shaft and the perpendicular line to the axis of the internal gear ring of the planetary roller screw is 30°±5°. In conventional bearings, the contact angle used in angular contact bearings is 15°.

[0008] Preferably, the lead screw is a stepped shaft with a larger diameter on the left side and external threads on the outer diameter surface. The lead screw has a thread length that is the same as that of the roller thread.

[0009] Preferably, the roller cage is interference-fitted with the lead screw and has clearance with the inner side of the planetary roller lead screw internal gear ring shaft.

[0010] Preferably, the rolling elements are evenly separated by a rolling element cage.

[0011] Priority is given to the fact that the first motor end cover and the second motor end cover only contact the end face of the outer shell, thereby axially limiting the internal structure and protecting the inside of the device.

[0012] The beneficial effects of this application are as follows: This invention integrates the planetary roller screw component and bearing into a single design and manufacture. The drive part magnet and the outer ring of the planetary roller screw are integrated to form a rotor shaft. The original motor drive component and planetary roller screw are integrated into one unit to reduce the size. Furthermore, the cantilever support structure reduces the number of components such as couplings, further reducing the size. The motor rotation directly drives the outer ring of the planetary roller screw, eliminating the need for a coupling and reducing energy loss during transmission. Traditional arrangements of motors and planetary roller screws often suffer from low concentricity during installation. However, this invention eliminates this issue. Furthermore, the integrated design of the bearing inner ring raceway and the ball screw outer ring allows them to be combined on a single outer diameter surface. This enables single-set turning and grinding of the planetary roller screw internal gear shaft using conventional tools, eliminating the need to change the reference surface and ensuring machining accuracy. Measurement and assembly result in minimal error. An internal contact angle of 30±5° is formed, increasing initial preload. The entire mechanical structure is assembled as a single unit. This contact angle falls within the range of conventional angular contact bearings, allowing the bearing to withstand relatively large axial forces while also bearing a certain radial force. Compared to conventional structures, where the internal bearing cannot achieve adequate clearance and requires press fitting and physical interference fit, leading to deformation and decreased product accuracy, this invention significantly improves accuracy.

[0013] The present invention adopts an integrated ball bearing design with an internal contact angle of 30±5°, which can significantly improve the axial load capacity of the entire device compared with conventional bearing structures. This invention adopts an integrated ball bearing design with an "O"-shaped arrangement of 30±5° contact angle inside. Compared with conventional bearing structures, it improves axial rigidity and extends the support points of the entire rotor shaft to both sides, thereby improving the rotor's anti-overturning ability. This invention is a double-row angular contact bearing with a large internal space between the first and second rows of rolling elements. Compared with conventional bearings, this increases the storage space for grease inside the bearing, allowing it to be filled with a large amount of high-quality grease suitable for the operating conditions, thus extending the lubrication life of the components. The present invention adopts a herringbone sealing structure on both sides of the rolling bearing, which is beneficial for protecting against external foreign objects and providing a more suitable axial displacement seal, which is beneficial for product assembly. The felt seal is integrated in the end cover, which is beneficial for protecting the internal structure of the planetary screw and greatly reducing the entry of external foreign objects into the screw cavity. Attached Figure Description

[0014] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application.

[0015] Furthermore, throughout the accompanying drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the elements are not necessarily drawn to scale.

[0016] In the attached diagram: Figure 1 This is a semi-sectional three-dimensional schematic diagram according to an embodiment of this application; Figure 2This is a full sectional view according to an embodiment of this application; Figure 3 This is a schematic cross-sectional view of the internal contact angle portion in this application; Figure 4 yes Figure 2 Enlarged structural diagram at point I; Figure 5 yes Figure 2 Enlarged structural diagram of section II.

[0017] Figure label: 1. Main housing; 2. Bearing outer ring; 3. First row of rolling elements; 4. Planetary roller screw internal gear ring shaft; 5. Screw; 6. Second motor end cover; 7. Rolling element cage; 8. Sealing cover; 9. Motor rotor; 10. Motor stator; 11. Encoder; 12. First motor end cover; 13. Roller cage; 14. Roller; 15. Second row of rolling elements; 201. First row of outer ring raceway; 401. First row of inner ring raceway; 202. Second row of outer ring raceway; 402. Second row of inner ring raceway; 403. Screw through-thread; 501. External thread; 601. Felt sealing ring. Detailed Implementation

[0018] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0019] It should also be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. Unless otherwise specified, the embodiments and features described in this disclosure can be combined with each other.

[0020] It should be noted that the concepts of "one" and "two" mentioned in this disclosure are only used to distinguish different devices, modules or units, and are not used to limit the order of functions performed by these devices, modules or units or their interdependencies.

[0021] It should be noted that the terms "a" and "a plurality of" used in this disclosure are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0022] This disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] Example 1: Refer to Figures 1-5A high-precision integrated planetary roller screw device includes a main housing 1; a stepped cavity is provided inside the main housing 1; a motor stator 9 is fixedly connected to the middle side wall of the stepped cavity; a bearing outer ring 2 is connected to the right side wall of the stepped cavity; the bearing outer ring 2 is connected to the right side wall of the stepped cavity with an interference fit or a transition fit; a first row of outer ring raceways 201 is provided inside the bearing outer ring 2; a planetary roller screw internal gear ring shaft 4 is provided inside the stepped cavity; the axis of the planetary roller screw internal gear ring shaft 4 coincides with the axis of the stepped cavity; a first row of inner ring raceways 401 is provided on the outer surface of the planetary roller screw internal gear ring shaft 4; a first row of rolling elements 3 is provided between the first row of outer ring raceways 201 and the first row of inner ring raceways 401; a second row of outer ring raceways 3 is provided inside the bearing outer ring 2. In section 202, a second row of inner ring raceways 402 is provided on the outer surface of the planetary roller screw internal gear ring shaft 4, and a second row of rolling elements 15 is provided between the second row of outer ring raceways 202 and the second row of inner ring raceways 402; a magnet 10 is rigidly connected to the outer left side of the planetary roller screw internal gear ring shaft 4; an encoder 11 is fixedly provided on the left side wall of the stepped cavity; a screw thread 403 is provided on the inner side of the planetary roller screw internal gear ring shaft 4, a screw 5 is provided in the stepped cavity, the screw 5 coincides with the axis of the stepped cavity, a roller retainer 13 is interference-fitted to the left side of the screw 5, and several rollers 14 are rotatably connected to the right end of the roller retainer 13, the screw thread 403 is threadedly connected to the rollers 14; the rollers 14 are threadedly connected to the screw shaft 5.

[0024] The left end of the main housing 1 is fitted with a first motor end cover 12, and the right end of the main housing 1 is fitted with a second motor end cover 6. The inner side of the second motor end cover 6 has a gap with the lead screw 5. A felt sealing ring 601 is fixed to the inner side of the second motor end cover 6, and the felt sealing ring 601 forms a small gap with the lead screw 5.

[0025] There are sealing caps 8 between the outer ring 2 of the bearing and the inner gear ring shaft 4 of the planetary roller screw, and on both sides of the rolling element 3.

[0026] The contact angle between the straight line formed by the contact point of the rolling element 3 and the raceway of the outer ring 2 of the bearing and the raceway of the internal gear ring shaft 4 of the planetary roller screw and the perpendicular line to the axis of the internal gear ring shaft 4 of the planetary roller screw is 30°±5°.

[0027] The lead screw 5 is a stepped shaft with a larger diameter on the left side. The outer diameter surface of the lead screw 5 on the left side is provided with an external thread 501 that is threaded to the roller 14. The external thread 501 and the roller 14 have the same thread length.

[0028] The roller retainer 13 has a gap with the lead screw through internal thread 403.

[0029] A rolling element retainer 7 is provided between the rolling elements 3, and the rolling elements 3 are evenly separated by the rolling element retainer 7.

[0030] The second motor end cover 6 is in contact with the end face of the outer ring 2 of the bearing.

[0031] Working principle: When the encoder receives an external driver signal that changes the stator magnetic field, the rotor direction changes, and the internal gear ring shaft of the planetary roller screw in which the rotor is located rotates. The bearing between the internal gear ring shaft of the planetary roller screw and the housing serves as support. The internal gear ring shaft of the planetary roller screw drives the rollers to rotate around the screw. The rotation of the rollers drives the screw to move forward / backward, so as to perform work on the external workpiece.

[0032] The above description is merely a selection of preferred embodiments of this disclosure and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in the embodiments of this disclosure is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in the embodiments of this disclosure.

Claims

1. A high-precision integrated planetary roller screw device, comprising: The utility model discloses a host shell (1), its characterized in being: The host shell (1) is equipped with a step cavity, a motor stator (9) is fixedly connected to the middle side wall in the step cavity, a bearing outer ring (2) is connected to the right side wall of the step cavity, a first column outer ring raceway (201) is arranged in the inner side of the bearing outer ring (2), a planetary roller screw inner tooth ring shaft (4) is arranged in the step cavity, a first column inner ring raceway (401) is arranged on the outer surface of the planetary roller screw inner tooth ring shaft (4), a first column rolling element (3) is arranged between the first column outer ring raceway (201) and the first column inner ring raceway (401), a second column outer ring raceway (202) is arranged in the inner side of the bearing outer ring (2), a second column inner ring raceway (402) is arranged on the outer surface of the planetary roller screw inner tooth ring shaft (4), a second column rolling element (15) is arranged between the second column outer ring raceway (202) and the second column inner ring raceway (402), a magnetic steel (10) is rigidly connected to the left side outer side of the planetary roller screw inner tooth ring shaft (4), an encoder (11) is fixedly arranged on the left side side wall of the step cavity, a screw rod through-hole inner thread (403) is arranged in the inner side of the planetary roller screw inner tooth ring shaft (4), a screw rod (5) is arranged in the step cavity, the screw rod (5) is connected to a roller retainer (13) through the left side interference, a plurality of rollers (14) are rotatably connected to the right end of the roller retainer (13), the screw rod through-hole inner thread (403) is threadedly connected with the roller (14), and the roller (14) is threadedly connected with the screw rod shaft (5).

2. The high-precision integrated planetary roller screw device according to claim 1, characterized in that: The axis of the planetary roller screw inner tooth ring shaft (4) coincides with the axis of the step cavity, and the screw rod (5) coincides with the axis of the step cavity.

3. The high-precision integrated planetary roller screw device according to claim 1, characterized in that: The first motor end cover (12) is clamped to the left end of the host shell (1), the second motor end cover (6) is clamped to the right end of the host shell (1), and the inner side of the second motor end cover (6) is fixedly provided with a felt sealing ring (601).

4. The high-precision integrated planetary roller screw device according to claim 1, characterized in that: The sealing cover (8) is arranged between the bearing outer ring (2) and the planetary roller screw inner tooth ring shaft (4) and on both sides of the rolling element (3).

5. The high-precision integrated planetary roller screw device according to claim 1, characterized in that: The contact angle formed by the straight line of the contact points of the rolling element (3) and the raceways of the bearing outer ring (2) and the planetary roller screw inner tooth ring shaft (4) and the perpendicular line of the axis of the planetary roller screw inner tooth ring shaft (4) is 30°±5°.

6. The high-precision integrated planetary roller screw device according to claim 1, wherein: The screw rod (5) is a stepped shaft with a larger diameter on the left side, the outer thread (501) is arranged on the left side outer diameter surface of the screw rod (5) and is threadedly connected with the roller (14), and the outer thread (501) has the same length of thread as the roller (14).

7. The high-precision integrated planetary roller screw device according to claim 1, wherein: The roller retainer (13) has a gap with the screw rod through-hole inner thread (403).

8. The high-precision integrated planetary roller screw device of claim 1, wherein: The rolling element retainers (7) are arranged between the rolling elements (3) and uniformly separate the rolling elements (3).

9. The high-precision integrated planetary roller screw device according to claim 3, characterized in that: The second motor end cover (6) is in contact with the end surface of the bearing outer ring (2).

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