Planetary roller screw miniature linear actuator
By using a planetary roller screw pair and a design with direct connection between the motor and the screw, the density, structural stability and efficiency problems of existing micro linear actuators are solved, the efficient tight convexity and tight convexity of the transmission structure and the improvement of energy density are achieved, the shortcomings of energy density and structural compactness in the existing technology are solved, and the improvement of high precision and stability is achieved.
Patent Information
- Application Number
- CN202422657045.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-31
- Publication Date
- 2025-09-23
- Estimated Expiration
- 2034-10-31
AI Technical Summary
Existing micro linear actuators have deficiencies in energy density and structural compactness, making it difficult to achieve high output push-pull forces in a compact layout environment, and to maintain accuracy and stability during long-term operation or in extreme environments.
The design of planetary roller screw pair and direct connection between motor and screw improves the load-bearing capacity and energy density while reducing costs by reducing the lead and improving the structural integration.
The transmission structure of the linear actuator is more compact, the energy density is improved, the structural layout is more integrated, the cost is reduced, and high precision and stability are maintained in extreme environments.
Smart Images
Figure CN223378999U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of linear drive devices, in particular to a planetary roller screw micro linear actuator. Background Art
[0002] With the rapid development of industrial automation and precision manufacturing, the demand for micro linear actuators is growing. Micro linear actuators utilize electric, pneumatic, or hydraulic drive methods to convert input rotary motion into linear motion, achieving precise control of the load. Currently, there are various types of micro linear actuators on the market, including electric micro linear drives and precision linear actuators.
[0003] While existing technologies have made significant progress in improving the comprehensive capabilities of micro linear actuators, they are limited in terms of energy density. This makes it difficult to achieve high output forces in compact environments. Furthermore, maintaining accuracy and stability over long periods of operation or in extreme environments remains a challenge. Utility Model Content
[0004] In response to the technical problems of defects in existing linear actuators, the utility model provides a planetary roller screw micro linear actuator, which effectively reduces the lead by using a planetary roller screw pair, thereby improving the load-bearing capacity while making the transmission structure of the linear actuator more compact and improving the energy density; and adopts a design of direct connection between the motor and the screw, which effectively improves the integration of the structural layout and reduces costs.
[0005] The technical solution provided by the utility model is: a planetary roller screw micro linear actuator, comprising a main housing, with a front end cover and a rear housing fixedly provided at both ends of the main housing respectively; a first cavity and a second cavity that are connected are provided in the main housing, and a third cavity that is connected to the second cavity is provided in the rear housing; a planetary roller screw pair is provided in the first cavity, and the planetary roller screw pair includes a nut, a screw and a plurality of rollers, the screw extends from the first cavity to the second cavity and the third cavity, the rollers are evenly arranged between the screw and the nut, the rollers include a first meshing section and a second meshing section, the middle diameter of the first meshing section is larger than the middle diameter of the second meshing section, the first meshing section and the part of the screw located in the first cavity are engaged with each other The external thread is engaged, and the second engaging section is engaged with the internal thread of the nut; a linear displacement sensor is arranged between the nut and the main shell, and a push rod is fixedly arranged at one end of the nut, and part of the push rod extends to the outside of the main shell; a motor is arranged in the second cavity, and the motor includes a stator and a rotor, the stator is fixedly connected to the main shell, and the rotor is fixed to the part of the screw located in the second cavity; a control unit is arranged in the third cavity, and a rotary encoder is arranged between the control unit and the end of the screw; a spherical bearing is provided at one end of the rear shell, and a tension and pressure sensor is integrated on the rear shell; the motor, rotary encoder, linear displacement sensor and tension and pressure sensor are all electrically connected to the control unit.
[0006] Optionally, the second engaging section is provided at two locations, and is respectively located on both sides of the first engaging section.
[0007] Optionally, the planetary roller screw pair further includes a retaining frame, wherein the retaining frame is located between the nut and the screw, and both ends of the roller are rotatably connected to the retaining frame respectively.
[0008] Optionally, the number of thread heads of the lead screw and the nut is the same, and the thread profiles of the lead screw and the nut are both triangular.
[0009] Optionally, the lead of the threads on the first meshing segment and the second meshing segment is zero, and the thread profiles on the first meshing segment and the second meshing segment are semicircular.
[0010] Optionally, a sheath is fixedly provided on the outside of the nut, and the sheath is slidably fitted with the inner wall of the first cavity.
[0011] Optionally, the linear displacement sensor includes a first reading unit and a magnetic grating, the magnetic grating is fixedly arranged on the outside of the sheath, the first reading unit is fixedly arranged on the inside of the first cavity, the first reading unit is arranged opposite to the magnetic grating, and the first reading unit is electrically connected to the control unit.
[0012] Optionally, the rotary encoder includes a second reading unit and a magnetic pole, a magnet sheath is fixedly provided at one end of the lead screw, the magnetic pole is fixedly provided on the magnet sheath, the magnetic pole is arranged opposite to the second reading unit, and the second reading unit is electrically connected to the control unit.
[0013] Optionally, a baffle is fixedly provided in the first cavity near the second cavity, and the baffle is used to abut against the nut.
[0014] Optionally, a first bearing and a second bearing are provided between the lead screw and the main housing, the first bearing is located in the middle of the lead screw, and the second bearing is located at an end of the lead screw close to the control unit.
[0015] Beneficial effects
[0016] The technical solution provided by the present invention has the following beneficial effects compared with the existing technology: in order to solve the technical problems of defects in existing linear actuators, the present invention effectively reduces the lead by using a planetary roller screw pair, thereby improving the load-bearing capacity while making the transmission structure of the linear actuator more compact and improving the energy density; and adopts a design of direct connection between the motor and the screw, which effectively improves the integration of the structural layout and reduces costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 This is a schematic structural diagram of the planetary roller screw micro linear actuator proposed in an embodiment of the present utility model.
[0018] Figure 2 This is a schematic cross-sectional view of the structure of the planetary roller screw micro linear actuator proposed in an embodiment of the present utility model. DETAILED DESCRIPTION
[0019] In order to further understand the content of the present invention, the present invention is described in detail with reference to the accompanying drawings and embodiments.
[0020] The present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific examples described herein are intended solely to illustrate the relevant utility model and are not intended to limit the utility model. It should also be noted that, for ease of description, only the relevant portions of the utility model are shown in the accompanying drawings. Terms such as "first," "second," and so on, used in the present utility model are provided for the convenience of describing the technical solution of the present utility model and do not have a specific limiting effect. They are general references and do not constitute a limitation on the technical solution of the present utility model. It should be noted that, unless conflicting, the embodiments and features within the embodiments of the present application may be combined with one another. In the description of the present utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating positions or locations, are based on the positions or locations shown in the accompanying drawings and are intended solely to facilitate the description of the present utility model and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Unless otherwise expressly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be a communication between the internal parts of two components. For those of ordinary skill in the art, the specific meanings of the above terms in this utility model can be understood according to the specific circumstances. Multiple technical solutions in the same embodiment, as well as multiple technical solutions in different embodiments, can be arranged and combined to form new technical solutions that do not contain contradictions or conflicts, and all of these are within the scope of protection claimed by this utility model.
[0021] Example 1
[0022] Combined with attachment Figure 1-2 This embodiment proposes a planetary roller screw micro linear actuator, including a main housing 10, with a front end cover 11 and a rear housing 12 fixedly provided at both ends of the main housing 10; a first cavity 101 and a second cavity 102 that are connected are provided in the main housing 10, and a third cavity 103 that is connected to the second cavity 102 is provided in the rear housing 12.
[0023] A planetary roller screw pair is arranged in the first cavity 101, and the planetary roller screw pair includes a nut 13, a screw 14 and a plurality of rollers 15. The screw 14 extends from the first cavity 101 to the second cavity 102 and the third cavity 103. The rollers 15 are evenly arranged between the screw 14 and the nut 13. The rollers 15 include a first meshing section 151 and a second meshing section 152. The middle diameter of the first meshing section 151 is larger than the middle diameter of the second meshing section 152. The first meshing section 151 meshes with the external thread of the part of the screw 14 located in the first cavity 101, and the second meshing section 152 meshes with the internal thread of the nut 13; a linear displacement sensor is arranged between the nut 13 and the main housing 10, and a push rod 24 is provided at one end of the nut 13, and part of the push rod 24 extends to the outside of the main housing 10.
[0024] A motor is disposed in the second cavity 102 . The motor includes a stator 16 and a rotor 17 . The stator 16 is fixedly connected to the main housing 10 , and the rotor 17 is fixed to a portion of the lead screw 14 located in the second cavity 102 .
[0025] A control unit 18 is provided in the third cavity 103, and a rotary encoder is provided between the control unit 18 and the end of the screw 14; a spherical bearing 19 is provided at one end of the rear shell 12, and a tension and pressure sensor is integrated on the rear shell 12; the motor, rotary encoder, linear displacement sensor and tension and pressure sensor are all electrically connected to the control unit 18.
[0026] Combined with the structural form described above, the main working principle of the planetary roller screw micro linear actuator of this embodiment is: the control unit 18 controls the motor to drive the screw 14 in the planetary roller screw pair to rotate, and the nut 13 in the planetary roller screw pair converts the rotational motion of the screw 14 into linear motion, driving the push rod 24 to translate, and the push rod 24 is connected to the external mechanism, thereby realizing the output of linear motion.
[0027] In this embodiment of the planetary roller screw pair, threads are machined into the nut 13, threads are machined into the lead screw 14, and roller 15 includes a first meshing section 151 and a second meshing section 152. The median diameter of the first meshing section 151 is larger than the median diameter of the second meshing section 152. The first meshing section 151 meshes with the external threads of the portion of the lead screw 14 located within the first cavity 101, while the second meshing section 152 meshes with the internal threads of the nut 13. Thus, the lead screw 14, roller 15, and nut 13 form a differential planetary roller screw, ensuring the precision and stability of the linear actuator.
[0028] In a preferred embodiment, two second engagement segments 152 are provided, and are located on both sides of the first engagement segment 151 , respectively, so that the force on the roller 15 can be more balanced, and the roller 15 can be prevented from tilting.
[0029] Furthermore, the planetary roller screw pair also includes a cage 20, which is located between the nut 13 and the screw 14. The two ends of the roller 15 are rotatably connected to the cage 20. The arrangement of the cage 20 also serves to ensure the stability of the arrangement of the roller 15, thereby ensuring efficient, precise, and stable movement of the planetary roller screw pair.
[0030] In a preferred embodiment, the screw 14 and nut 13 have the same number of thread starts, and both have triangular thread profiles. Furthermore, the lead of the threads on the first and second meshing segments 151, 152 can be set to zero, i.e., annular threads, with the thread profiles of the first and second meshing segments 151, 152 being semicircular. This creates a differential planetary roller screw pair that effectively reduces the lead, improving load capacity while making the linear actuator's transmission structure more compact and increasing energy density.
[0031] In this embodiment, the motor is preferably a frameless torque motor. The motor's stator 16 drives the motor's rotor 17, which in turn drives the lead screw 14 to rotate, thereby driving the nut 13 to move linearly. Specifically, the motor rotor 17 is directly fixed to the lead screw 14, achieving a direct connection with the lead screw 14. This effectively eliminates the need for an intermediate gear reduction mechanism, significantly improving the structural integration while reducing costs.
[0032] The movement of the lead screw 14 is controlled by a motor, which is in turn controlled by a control unit 18. A rotary encoder on the control unit 18 outputs the number of revolutions of the lead screw 14 to the control unit 18. A linear displacement sensor outputs the linear motion of the nut 13 to the control unit 18. A tension and pressure sensor outputs the applied tension and pressure to the control unit 18. Because the rotary encoder and linear displacement sensor are co-located on the lead screw 14, they operate synchronously, and both utilize absolute value control. Consequently, the control unit 18 combines the input information from the rotary encoder, linear displacement sensor, and tension and pressure sensor to control the movement of the linear actuator's push rod 24.
[0033] In other embodiments, a sheath 21 is fixedly mounted on the outside of the nut 13, and the sheath 21 slides against the inner wall of the first cavity 101. The sheath 21 is configured to directly slide against the main housing 10. Preferably, the nut 13 is directly pressed into the sheath 21, and the sheath 21 is made of a non-metallic material, which can reduce the coefficient of friction, reduce energy consumption, and improve transmission efficiency. Furthermore, when the push rod 24 is directly connected to the sheath 21, the sheath 21 and push rod 24 can be connected using a threaded connection.
[0034] In this embodiment, a linear displacement sensor is disposed between the nut 13 and the main housing 10. Combined with the aforementioned arrangement of the sheath 21, in a preferred embodiment, the linear displacement sensor includes a first reading unit 104 and a magnetic grid 105. The magnetic grid 105 is fixedly disposed on the outside of the sheath 21, and the first reading unit 104 is fixedly disposed on the inside of the first cavity 101. The first reading unit 104 and the magnetic grid 105 are disposed opposite each other and are electrically connected to the control unit 18. Thus, the sheath 21 is used to implement the arrangement of the linear displacement sensor. Since the sheath 21 is fixed to the nut 13, the linear displacement sensor can accurately read the displacement data of the nut 13.
[0035] Furthermore, the rotary encoder is preferably configured as follows: the rotary encoder includes a second reading unit 106 and a magnetic pole 107. A magnet sheath is fixedly mounted on one end of the lead screw 14. The magnetic pole 107 is fixedly mounted on the magnet sheath. The magnetic pole 107 is positioned opposite the second reading unit 106. The second reading unit 106 is electrically connected to the control unit 18. Thus, the magnetic pole 107 is directly fixed to the end of the lead screw 14, allowing accurate reading of the rotation data of the lead screw 14.
[0036] In other embodiments, a baffle 108 is fixedly provided in the first cavity 101 near the second cavity 102 , and the baffle 108 is used to abut against the nut 13 , thereby limiting the movement of the nut 13 .
[0037] Furthermore, in another embodiment, a first bearing 22 and a second bearing 23 are disposed between the lead screw 14 and the main housing 10. The first bearing 22 is located in the middle of the lead screw 14, and the second bearing 23 is located at the end of the lead screw 14 near the control unit 18. Both the first bearing 22 and the second bearing 23 are deep groove ball bearings to ensure smooth and stable movement of the lead screw 14. Combined with the aforementioned baffle 108, the first bearing 22 in the middle of the lead screw 14 can be positioned and secured by the baffle 108 and the baffle within the main housing 10.
[0038] To sum up, in order to solve the technical problems of defects in existing linear actuators, a planetary roller screw micro linear actuator in this embodiment effectively reduces the lead by using a planetary roller screw pair, thereby improving the load-bearing capacity and making the transmission structure of the linear actuator more compact and improving the energy density; and adopts a design of direct connection between the motor and the screw 14, which effectively improves the integration of the structural layout and reduces the cost.
[0039] The above is a schematic description of the present invention and its embodiments, which is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by this and, without departing from the inventive purpose of the present invention, designs a structure and embodiment similar to the technical solution without inventiveness, they shall fall within the scope of protection of the present invention.
Claims
1. A planetary roller screw micro linear actuator, characterized in that: The invention comprises a main shell (10), wherein a front cover (11) and a rear shell (12) are fixedly provided at both ends of the main shell (10); a first cavity (101) and a second cavity (102) are provided in the main shell (10), and a third cavity (103) is provided in the rear shell (12) and is in communication with the second cavity (102); A planetary roller screw pair is provided in the first cavity (101), the planetary roller screw pair comprising a nut (13), a screw (14) and a plurality of rollers (15), the screw (14) extending from the first cavity (101) to the second cavity (102) and the third cavity (103), the rollers (15) being evenly arranged between the screw (14) and the nut (13), the rollers (15) comprising a first meshing section (151) and a second meshing section (152), the first meshing section (151) ) has a median diameter greater than that of the second meshing section (152), the first meshing section (151) meshes with the external thread of a portion of the lead screw (14) located in the first cavity (101), and the second meshing section (152) meshes with the internal thread of the nut (13); a linear displacement sensor is provided between the nut (13) and the main housing (10), a push rod (24) is fixedly provided at one end of the nut (13), and a portion of the push rod (24) extends to the outside of the main housing (10); A motor is provided in the second cavity (102), the motor comprising a stator (16) and a rotor (17), the stator (16) being fixedly connected to the main housing (10), and the rotor (17) being fixed to a portion of the lead screw (14) located in the second cavity (102); A control unit (18) is provided in the third cavity (103), and a rotary encoder is provided between the control unit (18) and the end of the lead screw (14); a spherical bearing (19) is provided at one end of the rear housing (12), and a tension and pressure sensor is integrated on the rear housing (12); the motor, the rotary encoder, the linear displacement sensor and the tension and pressure sensor are all electrically connected to the control unit (18).
2. The planetary roller screw micro linear actuator according to claim 1, characterized in that: The second engaging section (152) is provided at two locations, and is respectively located on both sides of the first engaging section (151).
3. The planetary roller screw micro linear actuator according to claim 1, characterized in that: The planetary roller screw pair further includes a retaining frame (20), the retaining frame (20) is located between the nut (13) and the screw (14), and both ends of the roller (15) are rotatably connected to the retaining frame (20).
4. The planetary roller screw micro linear actuator according to claim 1, characterized in that: The number of thread heads of the lead screw (14) and the number of thread heads of the nut (13) are the same, and the thread profiles of the lead screw (14) and the nut (13) are both triangular.
5. A planetary roller screw micro linear actuator according to claim 1 or 4, characterized in that: The lead of the threads on the first meshing section (151) and the second meshing section (152) is zero, and the thread profiles on the first meshing section (151) and the second meshing section (152) are semicircular.
6. The planetary roller screw micro linear actuator according to claim 1, characterized in that: A sheath (21) is fixedly provided on the outside of the nut (13), and the sheath (21) is in sliding engagement with the inner wall of the first cavity (101).
7. The planetary roller screw micro linear actuator according to claim 6, characterized in that: The linear displacement sensor comprises a first reading unit (104) and a magnetic grid (105), wherein the magnetic grid (105) is fixedly arranged on the outside of the sheath (21), and the first reading unit (104) is fixedly arranged on the inside of the first cavity (101). The first reading unit (104) and the magnetic grid (105) are arranged opposite to each other, and the first reading unit (104) is electrically connected to the control unit (18).
8. The planetary roller screw micro linear actuator according to claim 1, characterized in that: The rotary encoder includes a second reading unit (106) and a magnetic pole (107), one end of the lead screw (14) is fixedly provided with a magnetic sheath, the magnetic pole (107) is fixedly provided on the magnetic sheath, the magnetic pole (107) and the second reading unit (106) are arranged opposite to each other, and the second reading unit (106) is electrically connected to the control unit (18).
9. The planetary roller screw micro linear actuator according to claim 1, characterized in that: A baffle (108) is fixedly provided in the first cavity (101) near the second cavity (102), and the baffle (108) is used to abut against the nut (13).
10. The planetary roller screw micro linear actuator according to claim 1, characterized in that: A first bearing (22) and a second bearing (23) are provided between the lead screw (14) and the main housing (10), wherein the first bearing (22) is located in the middle of the lead screw (14), and the second bearing (23) is located at one end of the lead screw (14) close to the control unit (18).