A reverse type planetary roller screw integrated servo electric cylinder

Abstract

This invention discloses an integrated servo electric cylinder with a reverse planetary roller screw, comprising a housing, a motor stator disposed inside the housing, a magnetic ring disposed inside the motor stator, a screw nut disposed inside the magnetic ring, a reverse planetary roller screw disposed inside the screw nut, a front end cover disposed on one side of the housing, a rear end cover disposed on the other side of the housing, an encoder magnet holder disposed inside the housing and located on one side of the screw nut, an encoder magnet disposed on the encoder magnet holder, an encoder disposed on one side of the encoder magnet, a gland disposed on the rear end cover, and an anti-rotation joint bearing disposed on one side of the reverse planetary roller screw. The advantages are: compact structure, space saving; convenient installation, plug-and-play; intelligent control, simple debugging; high precision and high response.

Description

Technical Field

[0001] This invention relates to the field of servo electric cylinder technology, and in particular to a reverse-type planetary roller screw integrated servo electric cylinder. Background Technology

[0002] Traditional split-type electric cylinder solutions, which use a "motor + coupling + ball screw" approach, are gradually showing their limitations when dealing with emerging high-end applications. Although ball screws have high transmission efficiency, their point contact force distribution becomes a weakness under extremely high loads, impact resistance, and long lifespan requirements. On the other hand, traditional split-type electric cylinders are relatively large. In some high-end applications, such as humanoid robot joints, medical devices, and semiconductors, there are stringent requirements for the external dimensions of the electric cylinder. This necessitates the adoption of integrated design technology to reduce the size of the electric cylinder and meet the needs of high-end applications.

[0003] The market urgently needs a new type of integrated electric cylinder that combines high rigidity, large thrust, long life, high precision and fast response. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a reverse planetary roller screw integrated servo electric cylinder, including a housing, a motor stator disposed inside the housing, a magnetic ring disposed inside the motor stator, a screw nut disposed inside the magnetic ring, a reverse planetary roller screw disposed inside the screw nut, a front end cover disposed on one side of the housing, a rear end cover disposed on the other side of the housing, an encoder magnet holder disposed inside the housing and located on one side of the screw nut, an encoder magnet disposed on the encoder magnet holder, an encoder disposed on one side of the encoder magnet, a gland head disposed on the rear end cover, and a reverse planetary roller screw disposed on the screw nut. The anti-rotation spherical bearing is located on one side of the ball screw. The reverse planetary ball screw is axially movable and installed inside the ball screw nut. The encoder magnet is mounted on the encoder magnet holder and is non-contactly connected to the encoder. The encoder converts the magnetic field signal into an electrical signal through a Hall sensor chip. When the magnetic pole is close to the Hall chip, the Hall sensor detects that the magnetic field is greater than a certain value Ks, outputs a low level and maintains it; when the detected magnetic field is less than a certain value Kn, it outputs a high level and maintains it. The anti-rotation spherical bearing is installed at one end of the reverse planetary ball screw, and the encoder is located inside the drive plate.

[0005] As a further supplement to this technical solution, a rear bearing housing is also provided inside the housing. The rear bearing housing is housed inside the housing and one end of it rests against the housing. A first four-point contact deep groove ball bearing is installed between the rear bearing housing and the lead screw nut. The inner ring of the first four-point contact deep groove ball bearing is tightly fitted with the outer cylindrical surface of the lead screw nut of the reverse planetary roller lead screw.

[0006] As a further supplement to this technical solution, a rear bearing cover is also provided on the side of the rear bearing housing near the rear end cover. The rear bearing cover is connected to the drive plate by screws, and the rear bearing cover is connected to the rear bearing housing by screws.

[0007] As a further supplement to this technical solution, a rear buffer pad is also provided on one side of the encoder magnet holder, and the rear buffer pad is installed inside the encoder magnet holder.

[0008] As a further supplement to this technical solution, a second four-point contact deep groove ball bearing is provided between the housing and the lead screw nut, and the inner ring of the second four-point contact deep groove ball bearing is tightly fitted with the outer cylindrical surface of the lead screw nut of the reverse planetary roller lead screw.

[0009] As a further supplement to this technical solution, a round nut is also installed on the lead screw nut, and the internal thread of the round nut is connected to the external thread of the lead screw nut of the reverse planetary roller lead screw.

[0010] As a further supplement to this technical solution, a front buffer pad is provided between the front end cover and the lead screw nut, and the front buffer pad is connected to the front end cover by screws.

[0011] As a further supplement to this technical solution, a graphite copper sleeve is fitted on the side of the reverse planetary roller screw near the front end cover, the outer side of the graphite copper sleeve abuts against the inside of the front end cover, and the reverse planetary roller screw is fitted on the graphite copper sleeve.

[0012] As a further supplement to this technical solution, a dustproof ring is provided between the front end cover and the reverse planetary roller screw. The dustproof ring is housed inside the front end cover, and the reverse planetary roller screw is sleeved inside the dustproof ring.

[0013] Its advantages are that it has a compact structure and saves space: the servo motor, driver and controller are integrated into the housing, eliminating the need for an external electrical control cabinet and reducing the overall installation space by more than 70%. Easy to install and plug-and-play: The quick-connect aviation connectors eliminate the need for complex motor alignment, coupling installation and driver wiring, greatly reducing the risk of failure due to improper installation. Intelligent control and simple debugging: Built-in zero-return algorithm and preset motion parameters, no need for external sensors and complex servo debugging, parameter tuning and drag teaching can be completed quickly through software; High precision and high response: It adopts servo closed-loop control, and the repeatability of positioning can reach ±0.01mm; the response speed is fast, and the positioning time is as low as 0.05ms, which far exceeds that of traditional split electric cylinders. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a cross-sectional structural schematic diagram of the present invention; In the diagram: 1. Housing; 2. Motor stator; 3. Magnetic ring; 4. Lead screw nut; 5. Reverse planetary roller lead screw; 6. Front cover; 7. Rear cover; 8. Encoder magnet holder; 9. Encoder magnet; 10. Encoder; 11. Gland head; 12. Anti-rotation spherical plain bearing; 13. Rear bearing housing; 14. First four-point contact deep groove ball bearing; 15. Rear bearing cover; 16. Rear buffer pad; 17. Second four-point contact deep groove ball bearing; 18. Round nut; 19. Front buffer pad; 20. Graphite copper sleeve; 21. Dust seal; 22. Drive board. Detailed Implementation

[0015] To facilitate a clearer understanding of this technical solution for those skilled in the art, the following will be described in conjunction with the appendix. Figure 1-2 The technical solution of the present invention is described in detail below: This invention employs a reverse-type planetary roller screw 5, providing an ideal technical core for integrated electric cylinders. Under the same load, the reverse-type planetary roller screw 5 is one-third smaller in volume than a ball screw. Its core "reverse" design—nut rotation and linear output of the screw—breaks through the traditional mindset of screw rotation and nut linear output, bringing multiple revolutionary advantages: the screw nut 4 can be directly used as the rotor of a frameless torque motor, eliminating intermediate transmission links such as couplings and reducers, achieving true mechatronics integration, and significantly reducing axial dimensions and overall weight; the line contact method between the rollers and the thread allows its load-bearing capacity to reach 3-5 times that of a ball screw of the same size, with strong impact resistance and a lifespan 15 times longer than that of a ball screw, while maintaining high transmission efficiency and high precision.

[0016] A reverse planetary roller screw integrated servo electric cylinder includes a housing 1, a motor stator 2 disposed inside the housing 1, a magnetic ring 3 disposed inside the motor stator 2, a screw nut 4 disposed inside the magnetic ring 3, a reverse planetary roller screw 5 disposed inside the screw nut 4, a front end cover 6 disposed on one side of the housing 1, a rear end cover 7 disposed on the other side of the housing 1, an encoder magnet seat 8 disposed inside the housing 1 and located on one side of the screw nut 4, an encoder magnet 9 disposed on the encoder magnet seat 8, an encoder 10 disposed on one side of the encoder magnet 9, a gland head 11 disposed on the rear end cover 7, and an anti-rotation joint bearing 12 disposed on one side of the reverse planetary roller screw 5. The reverse planetary roller screw 5 is axially movable and installed inside the screw nut 4. The encoder magnet 9 is mounted on the encoder magnet seat 8, and the encoder magnet 9 and the encoder 10 are connected non-contactly. The encoder is connected via a Hall sensor core. The chip converts the magnetic field signal into an electrical signal. When the magnetic pole is close to the Hall chip, the Hall chip detects that the magnetic field is greater than a certain value Ks, outputs a low level and maintains it; when the detected magnetic field is less than a certain value Kn, it outputs a high level and maintains it. The anti-rotation joint bearing 12 is installed at one end of the reverse planetary roller screw 5, and the encoder 10 is set inside the drive plate 22. The external thread of the gland head 11 is connected to the internal thread on the rear cover 7, and the external thread of the encoder magnet seat 8 is connected to the internal thread of the nut of the reverse planetary roller screw 5. The drive plate and the rear bearing cover 15 are connected by 6 M2X4 cross-slot pan head screws; the rear bearing cover 15 and the rear bearing seat 13 are connected by 6 M2X4 cross-slot countersunk screws; the front buffer pad 19 and the front cover 6 are connected by 4 M2.5x6 socket head countersunk screws; the front cover 6 and the housing 1 are connected by 4 M5×20 socket head cap screws. The housing 1 is also provided with a rear bearing seat 13. The rear bearing seat 13 is housed in the housing 1 and one end of it rests against the housing 1. A first four-point contact deep groove ball bearing 14 is installed between the rear bearing seat 13 and the lead screw nut 4. The inner ring of the first four-point contact deep groove ball bearing 14 is tightly fitted with the outer cylindrical surface of the lead screw nut 4 of the reverse planetary roller lead screw 5. The rear bearing seat 13 is also provided with a rear bearing cover 15 near the rear end cover 7. The rear bearing cover 15 is connected to the drive plate by screws, and the rear bearing cover 15 is connected to the rear bearing seat 13 by screws.

[0017] The encoder magnet base 8 is also provided with a rear buffer pad 16 on one side, and the rear buffer pad 16 is installed inside the encoder magnet base 8.

[0018] Among them, a second four-point contact deep groove ball bearing 17 is provided between the housing 1 and the lead screw nut 4. The inner ring of the second four-point contact deep groove ball bearing 17 is tightly fitted with the outer cylindrical surface of the lead screw nut 4 of the reverse planetary roller lead screw 5.

[0019] The lead screw nut 4 is also equipped with a round nut 18, the internal thread of which is connected to the external thread of the lead screw nut 4 of the reverse planetary roller lead screw 5.

[0020] Among them, a front buffer pad 19 is provided between the front cover 6 and the lead screw nut 4. The front buffer pad 19 is connected to the front cover 6 by screws, using four 12.9 grade M5×20 socket head cap screws.

[0021] Among them, a graphite copper sleeve 20 is fitted on the side of the reverse planetary roller screw 5 near the front end cover 6. The outer side of the graphite copper sleeve 20 abuts against the inside of the front end cover 6, and the reverse planetary roller screw 5 is fitted on the graphite copper sleeve 20.

[0022] A dustproof ring 21 is provided between the front end cover 6 and the reverse planetary roller screw 5. The dustproof ring 21 is housed inside the front end cover 6, and the reverse planetary roller screw 5 is sleeved inside the dustproof ring 21.

[0023] Working Principle: This reverse planetary roller screw 5 is supported by a rigid retainer. An even number of rollers are fitted with the retainer with a clearance fit. The screw shaft ends are connected by retaining rings to prevent axial movement of the planetary rollers. To achieve reverse transmission, the rollers use left-hand threads, while the nut and screw use right-hand threads. Both the reverse planetary roller screw 5 and the screw nut 4 feature a 90° thread angle design and a 1.5mm pitch, effectively ensuring synchronous movement. The reverse planetary roller screw 5 and screw nut 4 employ a three-start helical design, while the rollers use a single-start helical design, perfectly meeting assembly and transmission ratio requirements. The involute gears at both ends of the rollers and screw feature a positive displacement design, significantly improving the bending strength of the gear root and the contact strength of the tooth surface, as well as increasing gear life and transmission performance, avoiding gear undercut and uneven load distribution.

[0024] It adopts a highly integrated design of components such as a reverse planetary roller screw 5, a frameless torque motor, a four-point contact deep groove ball bearing, an encoder 10, and a driver, achieving comprehensive performance with high thrust, impact resistance, high speed, small size, long life, high rigidity, high precision, low noise, and fast response.

[0025] The working principle of the integrated electric cylinder using the reverse planetary roller screw 5 is as follows: the rotor of the servo motor is directly coupled to the nut, and the rotation of the motor directly drives the rotation of the nut; the thread on the inner wall of the nut drives multiple planetary rollers, and the rollers "revolve" around the screw and "rotate" around their own axis at the same time; the rollers mesh with the thread of the central screw, converting the rotational motion into the linear extension and retraction motion of the screw along its axis, thereby outputting thrust or tension.

[0026] Operation process: When the stator 2 of the frameless torque motor is energized, the nut of the reverse planetary roller screw 5 rotates under the action of electromagnetic induction, which drives the rollers to "rotate" and "revolve", thereby driving the screw to perform reciprocating linear motion.

[0027] The above technical solutions only embody the preferred technical solutions of the present invention. Any modifications that may be made by those skilled in the art to certain parts thereof embody the principles of the present invention and fall within the protection scope of the present invention.

Claims

1. A reverse-type planetary roller screw integrated servo electric cylinder, characterized in that, Includes a housing (1), a motor stator (2) located inside the housing (1), a magnetic ring (3) located inside the motor stator (2), a lead screw nut (4) located inside the magnetic ring (3), a reverse planetary roller screw (5) located inside the lead screw nut (4), a front end cover (6) located on one side of the housing (1), a rear end cover (7) located on the other side of the housing (1), an encoder magnet holder (8) located inside the housing (1) and on one side of the lead screw nut (4), an encoder magnet (9) located on the encoder magnet holder (8), an encoder (10) located on one side of the encoder magnet (9), a gland head (11) located on the rear end cover (7), and a reverse planetary roller screw (5) located on the rear end cover (7). The anti-rotation joint bearing (12) is located on one side. The reverse planetary roller screw (5) is axially movable and installed inside the screw nut (4). The encoder magnet (9) is installed on the encoder magnet seat (8). The encoder magnet (9) is non-contactly connected to the encoder (10). The encoder (10) converts the magnetic field signal into an electrical signal through a Hall sensor chip. When the magnetic pole is close to the Hall chip, the Hall detects that the magnetic field is greater than a certain value Ks, outputs a low level and holds it. When the detected magnetic field is less than a certain value Kn, it outputs a high level and holds it. The anti-rotation joint bearing (12) is installed at one end of the reverse planetary roller screw (5). The encoder (10) is located inside the drive plate (22).

2. The reverse-type planetary roller screw integrated servo electric cylinder according to claim 1, characterized in that, The housing (1) is also provided with a rear bearing seat (13), which is housed in the housing (1) and one end of which rests against the housing (1). A first four-point contact deep groove ball bearing (14) is installed between the rear bearing seat (13) and the lead screw nut (4). The inner ring of the first four-point contact deep groove ball bearing (14) is tightly fitted with the outer cylindrical surface of the nut of the reverse planetary roller lead screw (5).

3. A reverse-type planetary roller screw integrated servo electric cylinder according to claim 2, characterized in that, The rear bearing housing (13) is also provided with a rear bearing cover (15) on the side near the rear end cover (7). The rear bearing cover (15) is connected to the drive plate by screws, and the rear bearing cover (15) is connected to the rear bearing housing (13) by screws.

4. A reverse-type planetary roller screw integrated servo electric cylinder according to claim 3, characterized in that, The encoder magnet holder (8) is also provided with a rear buffer pad (16) on one side, and the rear buffer pad (16) is installed inside the encoder magnet holder (8).

5. A reverse-type planetary roller screw integrated servo electric cylinder according to claim 4, characterized in that, A second four-point contact deep groove ball bearing (17) is provided between the housing (1) and the lead screw nut (4), and the inner ring of the second four-point contact deep groove ball bearing (17) is tightly fitted with the outer cylindrical surface of the lead screw nut (4) of the reverse planetary roller lead screw (5).

6. A reverse-type planetary roller screw integrated servo electric cylinder according to claim 5, characterized in that, A round nut (18) is also installed on the lead screw nut (4), and the internal thread of the round nut (18) is connected to the external thread of the lead screw nut (4) of the reverse planetary roller lead screw (5).

7. A reverse-type planetary roller screw integrated servo electric cylinder according to claim 6, characterized in that, A front buffer pad (19) is provided between the front end cover (6) and the lead screw nut (4), and the front buffer pad (19) and the front end cover (6) are connected by screws.

8. A reverse-type planetary roller screw integrated servo electric cylinder according to claim 7, characterized in that, A graphite copper sleeve (20) is fitted on the side of the reverse planetary roller screw (5) near the front end cover (6). The outer side of the graphite copper sleeve (20) rests against the inside of the front end cover (6), and the reverse planetary roller screw (5) is fitted on the graphite copper sleeve (20).

9. A reverse-type planetary roller screw integrated servo electric cylinder according to claim 8, characterized in that, A dustproof ring (21) is provided between the front end cover (6) and the reverse planetary roller screw (5). The dustproof ring (21) is housed inside the front end cover (6), and the reverse planetary roller screw (5) is sleeved inside the dustproof ring (21).

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