A linear actuator

Abstract

The application relates to the field of actuator structures, in particular to a linear actuator which comprises a shell, a frameless motor fixedly connected in the shell, a nut fixedly connected with a rotor of the frameless motor, a ball screw threadedly connected with the nut, and a rod end connecting piece connected with an external structure at one end of the ball screw exposed outside the shell, wherein the axial length of the linear actuator is greatly reduced by using the frameless motor, the radial length is slightly increased, the space occupation of the linear actuator is effectively reduced, and the linear actuator is more suitable for occasions with compact structure design requirements such as humanoid robots.

Description

Technical Field

[0001] This application relates to the field of actuator structures, and more particularly to a linear actuator. Background Technology

[0002] Linear actuators generally convert the rotation of a motor into linear motion. However, linear actuators used in robots have higher requirements, such as smaller space occupation, simpler structural design, and easier daily maintenance.

[0003] There are some linear actuators that drive ball screw assemblies via motors, thereby enabling the drive components to move linearly. For example, a linear actuator and humanoid robot are disclosed in CN120194130A.

[0004] In the above linear actuators, the motor is located at one end of the lead screw shaft, and a torque transmission component is set between the motor output shaft and the lead screw shaft, which makes the axial length of the linear actuator too large, making it difficult to meet the compact structural requirements of robots, especially some small service robots or humanoid robots. Utility Model Content

[0005] To better meet the requirement of compact structure in robots, this application provides a linear actuator.

[0006] The linear actuator provided in this application adopts the following technical solution.

[0007] A linear actuator includes a housing, within which a frameless motor is fixedly connected. The rotor of the frameless motor is fixedly connected to a nut, which is threadedly connected to a ball screw. One end of the ball screw, exposed outside the housing, is detachably connected to a rod end connector for connection to an external structure.

[0008] By adopting the above technical solution, the traditional series connection of the motor and ball screw is transformed into a parallel connection using a frameless motor, which greatly reduces the axial length of the linear actuator, with only a slight increase in the radial length. The space occupied by the linear actuator is greatly reduced, making it more suitable for humanoid robots and other applications that require a compact structure.

[0009] Optionally, a head support rotating component and a tail support rotating component are detachably connected inside the housing. The inner rings of both the head support rotating component and the tail support rotating component are detachably connected to a nut. The frameless motor is located between the head support rotating component and the tail support rotating component.

[0010] By adopting the above technical solution, the smooth rotation of the nut is ensured.

[0011] Optionally, the tail support rotating component is located on the side of the frameless motor away from the rod end connector, and the number of tail support rotating components is at least two.

[0012] By adopting the above technical solution, it is ensured that the nut is far away from the housing so that the end of the ball screw that extends out is not easy to wobble, thus ensuring the stability of the linear actuator during operation.

[0013] Optionally, the outer shell is formed with a shell limiting ring for the outer ring of the tail support rotating component to abut against, and a spacer is detachably connected inside the outer shell, with the spacer abutting against the side of the tail support rotating component away from the outer ring of the shell limiting ring.

[0014] By adopting the above technical solution, the stability of the outer ring of the tail support rotating component is ensured.

[0015] Optionally, the nut is formed with a nut positioning ring for the inner ring of the tail support rotating component to abut against, and the nut is detachably connected with a nut movable positioning ring, which abuts against the inner ring of the tail support rotating component away from the nut positioning ring.

[0016] By adopting the above technical solution, the stability of the inner ring of the tail support rotating component is ensured.

[0017] Optionally, the outer casing includes a shell that is connected through both ends, a tail cover and a front seat that are detachably connected to the openings at both ends of the shell, and the front seat allows one end of the ball screw to be exposed, and the head support rotating component is detachably connected to the front seat.

[0018] By adopting the above technical solution, the linear actuator can be easily disassembled and maintained.

[0019] Optionally, the ball screw includes a screw shaft threaded to a nut and an actuator rod fixedly connected to the screw shaft and exposed in the front seat. The front seat is detachably connected to a guide sleeve and a sealing ring for the actuator rod to pass through tightly.

[0020] By adopting the above technical solution, the stable movement of the actuator is ensured.

[0021] Optionally, a push-pull force sensor may be detachably connected to the end of the housing away from the rod end connector, and a sensor end connector may be detachably connected to the side of the push-pull force sensor away from the housing.

[0022] By adopting the above technical solution, the axial pressure borne by the linear actuator can be collected and fed back to the external control system in real time to achieve precise force control.

[0023] Optionally, an encoder is detachably connected inside the housing, and an encoder magnet base is detachably connected to the nut near the encoder end.

[0024] By adopting the above technical solution, the rotation angle of the nut is detected in real time, and the linear displacement is accurately calculated in combination with the lead parameter, thus forming a closed-loop position control.

[0025] In summary, this application includes at least the following beneficial effects.

[0026] By using a frameless motor, the traditional series connection of the motor and ball screw is transformed into a parallel connection, which greatly reduces the axial length of the linear actuator, with only a slight increase in the radial length. The space occupied by the linear actuator is greatly reduced, making it more suitable for applications such as humanoid robots that require a compact structure. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the main structure of this application;

[0028] Figure 2 This is a cross-sectional structural diagram of this application;

[0029] Figure 3 yes Figure 2 Enlarged view of point A in the middle.

[0030] Explanation of reference numerals in the attached drawings: 1. Housing; 2. Frameless motor; 3. Nut; 4. Ball screw; 41. Screw shaft; 42. Actuating rod; 43. Guide sleeve; 44. Sealing ring; 45. Push-pull force sensor; 46. Sensor end connector; 47. Encoder; 48. Encoder magnet seat; 5. Rod end connector; 51. Head support rotating component; 52. Tail support rotating component; 53. Housing limit ring; 54. Spacer ring; 55. Nut fixed limit ring; 56. Nut moving limit ring; 57. Housing; 58. Tail cover; 59. Front seat. Detailed Implementation

[0031] The present application will be further described in detail below with reference to the accompanying drawings.

[0032] This application discloses a linear actuator, referring to... Figure 1 The device includes a housing 1, inside which a frameless motor 2 is installed. A nut 3 is coaxially fixed to the inner wall of the rotor of the frameless motor 2. A ball screw 4 is coaxially threaded to the inner ring of the nut 3. The ball screw 4 can be exposed at one end of the housing 1.

[0033] Reference Figure 2The outer casing 1 includes a casing 57 with openings at both ends that are connected through it. A tail cover 58 and a front seat 59 are detachably connected to each end of the casing 57. The tail cover 58 can be connected to the casing 57 via bolts, and the front seat 59 can be threaded to the casing 57. The ball screw 4 includes a screw shaft 41 and an actuator 42 coaxially fixed to the end of the screw shaft 41. The screw shaft 41 is coaxially threaded to the casing 57, and the lead of the screw shaft 41 can be 1 mm. The actuator 42 passes through and protrudes from the front seat 59. One end of the actuator 42 protruding from the front seat 59 is coaxially threaded to a rod end connector 5. The rod end connector 5 can be a fisheye bearing for movable connections to related structures of the humanoid robot. A sealing ring 44 and a guide sleeve 43 are embedded in the front seat 59. The guide sleeve 43 abuts against the side of the sealing ring 44 facing inwards from the casing 57, allowing the actuator 42 to pass tightly through the guide sleeve 43 and the sealing ring 44.

[0034] Reference Figure 2 The outer casing 1 contains a detachable head support rotating component 51 and a tail support rotating component 52. The head support rotating component 51 and tail support rotating component 52 can be bearings or bushings. In this embodiment, the head support rotating component 51 can be a deep groove ball bearing or an angular contact ball bearing. The head support rotating component 51 is embedded in the front seat 59. There can be two tail support rotating components 52, with their end faces in close contact. The frameless motor 2 is located between the head support rotating component 51 and the tail support rotating component 52.

[0035] Reference Figure 2 and Figure 3 The inner circumference of the housing 57 is formed with a housing limiting ring 53, and the outer end face of the tail support rotating member 52 near the frameless motor 2 abuts against the housing limiting ring 53. The inner wall of the outer housing 1 is coaxially fitted with a spacer ring 54, which abuts against the outer end face of the tail support rotating member 52 away from the frameless motor 2. The tail cover 58 abuts against the end face of the spacer ring 54 away from the tail support rotating member 52, so that the outer ring of the tail support rotating member 52 is not easily moved.

[0036] Reference Figure 3 Nut 3 has a nut positioning ring 55 formed thereon, and the inner ring end face of the tail support rotating member 52 near the frameless motor 2 abuts against the nut positioning ring 55. The outer circumference of nut 3 is coaxially threaded with a nut moving ring 56, which abuts against the inner ring end face of the tail support rotating member 52 away from the frameless motor 2, so that the inner ring of the tail support rotating member 52 is not easily moved.

[0037] Reference Figure 2An encoder 47 is detachably connected inside the tail cover 58. An encoder magnet seat 48 is coaxially and detachably connected to the nut 3 near the encoder 47. The encoder 47 generates an electrical signal by detecting the change in the magnetic field of the encoder magnet seat 48. After processing, the encoder 47 obtains the rotation angle and number of turns of the nut 3. Combined with the lead of the lead screw shaft 41, the signal is converted into a linear displacement to form a closed-loop position control.

[0038] Reference Figure 1 A push-pull force sensor 45 is detachably connected to the end of the outer casing 1 away from the rod end connector 5. A sensor end connector 46 is detachably connected to the side of the push-pull force sensor 45 away from the outer casing 1 via bolts. The sensor end connector 46 can be a radial sliding bearing and can be used to connect related components of the humanoid robot. The push-pull force sensor 45 detects the axial force on the lead screw shaft 41 in real time and outputs a feedback signal. The external control system dynamically adjusts the input current of the frameless motor 2 based on the feedback signal to achieve precise control of the output force of the linear actuator.

[0039] The implementation principle of a linear actuator in this application embodiment is as follows: the rotor of the frameless motor 2 drives the nut 3 to rotate, so that the lead screw shaft 41 and the actuator rod 42 move linearly synchronously.

[0040] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A linear actuator, comprising a housing (1), characterized in that: A frameless motor (2) is fixedly connected inside the outer casing (1). The rotor of the frameless motor (2) is fixedly connected to a nut (3). The nut (3) is threadedly connected to a ball screw (4). One end of the ball screw (4) exposed outside the outer casing (1) is detachably connected to a rod end connector (5) for connection to an external structure.

2. A linear actuator according to claim 1, characterized in that: The outer casing (1) is detachably connected to a head support rotating part (51) and a tail support rotating part (52). The inner rings of the head support rotating part (51) and the tail support rotating part (52) are detachably connected to a nut (3). The frameless motor (2) is located between the head support rotating part (51) and the tail support rotating part (52).

3. A linear actuator according to claim 2, characterized in that: The tail support rotating component (52) is located on the side of the frameless motor (2) away from the rod end connector (5), and the number of tail support rotating components (52) is at least two.

4. A linear actuator according to claim 2, characterized in that: The outer shell (1) has a shell limiting ring (53) formed inside for the outer ring of the tail support rotating member (52) to abut against. The outer shell (1) has a spacer ring (54) detachably connected inside. The spacer ring (54) abuts against the outer ring of the tail support rotating member (52) away from the outer ring of the shell limiting ring (53).

5. A linear actuator according to claim 2, characterized in that: The nut (3) is formed with a nut positioning ring (55) for the inner ring of the tail support rotating member (52) to abut against. The nut (3) is detachably connected with a nut moving ring (56), which abuts against the inner ring of the tail support rotating member (52) away from the nut positioning ring (55).

6. A linear actuator according to claim 2, characterized in that: The outer shell (1) includes a shell (57) that is connected through both ends, a tail cap (58) and a front seat (59) that are detachably connected to the openings at both ends of the shell (57). The front seat (59) allows one end of the ball screw (4) to be exposed, and the head support rotating part (51) is detachably connected to the front seat (59).

7. A linear actuator according to claim 6, characterized in that: The ball screw (4) includes a screw shaft (41) threaded to a nut (3) and an actuator (42) fixedly connected to the screw shaft (41) and exposed in the front seat (59). The front seat (59) is detachably connected to a guide sleeve (43) and a sealing ring (44) for the actuator (42) to pass through tightly.

8. A linear actuator according to claim 1, characterized in that: A push-pull force sensor (45) is detachably connected to one end of the outer casing (1) away from the rod end connector (5), and a sensor end connector (46) is detachably connected to one side of the push-pull force sensor (45) away from the outer casing (1).

9. A linear actuator according to claim 1, characterized in that: An encoder (47) is detachably connected inside the housing (1), and an encoding magnet base (48) is detachably connected to the nut (3) near the end of the encoder (47).

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