Actuator rotation speed detection structure and actuator

Abstract

This invention discloses an actuator rotation speed detection structure and an actuator. The actuator rotation speed detection structure includes a housing, a motor, and a reduction mechanism. The motor includes a stator and a rotor, with a shaft sleeve connected to the rotor. The reduction mechanism has an input terminal connected to the rotor and an output terminal connected to the encoder shaft. The encoder shaft is provided with a first mounting surface, and the shaft sleeve is provided with a second mounting surface. A first magnetic ring is fixed to the first mounting surface, and a second magnetic ring is fixed to the second mounting surface. A PCB substrate is fixed to the housing, and the PCB substrate includes a third mounting surface, to which a first Hall element and a second Hall element are mounted. The first Hall element obtains the angle of the encoder shaft by cooperating with the first magnetic ring to detect the rotation angle of the first magnetic ring, and the second Hall element obtains the angle of the shaft sleeve by cooperating with the second magnetic ring to detect the rotation angle of the second magnetic ring. This invention simplifies the internal structure of the actuator, improves the integration density inside the actuator, and is advantageous for optimizing the space inside the actuator.

Description

TECHNICAL FIELD

[0001] The present invention relates to the technical field of robot driving, and in particular, relates to a rotation speed detection structure for an actuator and an actuator.

BACKGROUND ART

[0002] An actuator is a component inside a robot joint, which is used to provide power for relative motion between two movable members of the robot joint and to control the motion angles of the two movable members of the robot joint with high precision. To enable the robot joint to accurately execute related commands, a detection structure is usually arranged inside the actuator, so as to detect the angle of relevant members inside the actuator, especially the output end. A motor and a speed reduction mechanism are usually installed inside the actuator. The speed reduction mechanism transmits the output power of the motor to the output end of the actuator. In order to control the angle of the output end, it is usually necessary to arrange rotation angle detection units at the output end of the motor (the high-speed end of the actuator) and the output end of the actuator (the low-speed end) respectively. However, in the actuators of the prior art, the high-speed end detection unit and the low-speed end detection unit are arranged independently, which occupies a large internal space of the actuator and is disadvantageous to the miniaturization design of the external dimension of the actuator.

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0003] The present invention aims to solve the problems in the prior art that the integration degree of the high-speed end detection unit and the low-speed end detection unit is low and the occupied space is large by providing a rotation speed detection structure for an actuator and the actuator.

MEANS FOR SOLVING THE PROBLEMS

[0004] The object of the present invention is achieved by the following technical solutions.

[0005] The actuator's rotational speed detection structure includes a housing, a motor, and a reduction mechanism. The motor includes a stator that is fixedly engaged with the housing, and a rotor that fits the stator and is rotatable relative to the stator, the rotor being synchronously connected to a shaft sleeve that is pivotally mounted to the housing. The input terminal of the reduction mechanism is connected to the rotor, and the output terminal of the reduction mechanism is connected to an encoder shaft that is inserted into the shaft sleeve and mounted coaxially with the shaft sleeve. The encoder shaft is provided with a first mounting surface, and the shaft sleeve is provided with a second mounting surface. In the radial direction of the actuator, the second mounting surface is located outside the first mounting surface. A first magnetic ring is fixed to the first mounting surface, and a second magnetic ring is fixed to the second mounting surface. The central axes of the first and second magnetic rings coincide with the central axis of the encoder shaft. A PCB is fixed to the housing, and the PCB includes a third mounting surface that faces the first and second mounting surfaces. A first Hall element and a second Hall element are mounted on the third mounting surface. The first Hall element works in cooperation with the first magnetic ring to detect the rotation angle of the first magnetic ring, thereby obtaining the angle of the encoder shaft. The second Hall element works in cooperation with the second magnetic ring to detect the rotation angle of the second magnetic ring, thereby obtaining the angle of the shaft sleeve.

[0006] Alternatively, the first Hall element works in cooperation with the first magnetic ring to detect the rotational speed of the first magnetic ring and obtain the angular velocity of the encoder shaft, and the second Hall element works in cooperation with the second magnetic ring to detect the rotational speed of the second magnetic ring and obtain the angular velocity of the shaft sleeve.

[0007] According to the actuator rotation speed detection structure of an embodiment of the present invention, by providing a first mounting surface for attaching a first magnetic ring and a second mounting surface for attaching a second magnetic ring on the encoder shaft and shaft sleeve which are mated together, the first magnetic ring and the second magnetic ring can be positioned at the same or substantially the same position in the axial direction of the actuator. Therefore, by installing only one PCB board in the housing, two Hall elements that fit the two magnetic rings can be attached. In other words, the Hall elements corresponding to the two magnetic rings can share the same PCB board. This simplifies the internal structure of the actuator, improves the integration density inside the actuator, and is advantageous for optimizing the space inside the actuator. Furthermore, the low-speed end detection and high-speed end detection of the actuator can be concentrated in the same area inside the actuator, making it easier to lay out the internal wiring.

[0008] In a preferred embodiment, a first annular support is fixed to the encoder shaft in a removable manner, and a second annular support surrounding the outer circumference of the first annular support is fixed to the shaft sleeve in a removable manner. The upper surface of the first annular support forms a first mounting surface. The upper surface of the second annular support forms a second mounting surface. By fixing the first and second annular supports to the encoder shaft and shaft sleeve respectively in a removable manner, and by installing the first and second magnetic rings on the first and second annular supports, respectively, the assembly and inspection of the actuator can be facilitated.

[0009] In a preferred embodiment, the upper surface of the first annular support is provided with a first annular groove recessed downwards, and the first magnetic ring has a thickness equal to the depth of the first annular groove and is fitted into the first annular groove. The upper surface of the second annular support is provided with a second annular groove recessed downwards, and the second magnetic ring has a thickness equal to the depth of the second annular groove and is fitted into the second annular groove, so that the upper surfaces of the first magnetic ring and the second magnetic ring are flush. By mounting the first and second magnetic rings in a manner that they are recessed into the upper surfaces of the first and second annular supports, respectively, the gap between the first and second annular supports and the PCB substrate can be made relatively small. Furthermore, the two magnetic rings are offset from each other in the radial direction of the actuator, and the upper surfaces of the two magnetic rings are positioned flush in the axial direction of the actuator. As a result, the space occupied by the entire rotational speed detection structure in the axial direction of the actuator can be further reduced.

[0010] In a preferred embodiment, a mounting base is fitted onto the encoder shaft, and a tightening screw is threaded into the mounting base. The inner end of the tightening screw is fitted into a threaded hole provided on the encoder shaft, and the first annular support is fitted onto the mounting base and screwed into the mounting base. By installing the mounting base on the encoder shaft, the portion of the encoder shaft for mounting the first annular support has a relatively large outer diameter, and since the diameter of the encoder shaft is smaller than the diameter of the shaft sleeve, after increasing the diameter with the mounting base, the first annular support can be brought as close as possible to the second annular support in the radial direction of the actuator. As a result, the first mounting surface can be brought closer to the second mounting surface, the radial distance between the first magnetic ring and the second magnetic ring of the actuator is relatively small, the mounting requirement for two Hall elements can be met with only a small-sized PCB board, the space occupied by the PCB board can be further reduced, and this is advantageous for optimizing the internal space of the actuator. Assembling the first magnetic ring and the first annular support as an assembly and screwing the assembly to the encoder shaft makes the assembly of the actuator simple and easy.

[0011] In a preferred embodiment, the second annular support is fitted onto the upper part of the shaft sleeve and screw-fitted to the shaft sleeve.

[0012] In a preferred embodiment, the housing includes an outer wall, an upper wall extending inward from the top of the outer wall along the radial direction of the actuator, and a support wall extending downward from the inner edge of the upper wall. A mounting space is formed between the support wall and the side wall, and the motor is positioned within this mounting space, with the stator fixedly connected to the outer circumference of the support wall. The rotor surrounds the outer circumference of the stator, and the PCB board is fixedly connected to the upper wall so as to be positioned above the first and second mounting surfaces. The outer wall, upper wall, and support wall form a U-shaped cross-section structure in the housing, providing mounting space for the motor and offering better protection for the motor. The upper wall is also used to provide a mounting base for the PCB board, facilitating the mounting of the PCB board.

[0013] In a preferred embodiment, a mounting plate is fixedly connected to the upper wall, and an annular rib projecting upward is provided on the upper surface of the mounting plate. The outer edge of the PCB substrate is circular and abuts against the inner edge of the annular rib. The annular rib is used to position the PCB substrate radially to the actuator, and two Hall elements pre-mounted on the PCB substrate can be aligned with two magnetic rings radially to the actuator. This improves the mounting accuracy of the PCB substrate and ensures that the rotational speed detection at the low-speed and high-speed ends of the actuator has high accuracy.

[0014] In a preferred embodiment, the reduction mechanism is a harmonic reducer. The circular spline of the harmonic reducer is fixedly engaged with the housing, and the web generator of the harmonic reducer is connected to the bottom of the rotor via a connecting bracket. An output flange, pivotally mounted to the housing via bearings, is fixed to the flex spline of the harmonic reducer, and the bottom of the encoder shaft is fixedly connected to the output flange. A fixing bracket is fixedly mounted above the upper wall, and the upper part of the encoder shaft is pivotally mounted to the fixing bracket via bearings. In this way, both the upper and lower ends of the encoder shaft are pivotally mounted to the housing via bearings, and the bearings provide radial support to the encoder shaft, making the rotation of the encoder shaft more stable. As a result, the accuracy of rotational speed detection at the low-speed end is improved.

[0015] In a preferred embodiment, the lower end of the shaft sleeve is fixedly connected to a connecting bracket by bolts, thereby synchronously connecting the shaft sleeve and the rotor. The shaft sleeve is located inside the support wall and is pivotally mounted to the support wall via bearings. The support wall and bearings are used to provide radial support to the shaft sleeve, making the rotation of the shaft sleeve more stable and improving the accuracy of rotational speed detection at the high-speed end.

[0016] The actuator includes a rotation speed detection structure for the actuator described above. [Brief explanation of the drawing]

[0017] [Figure 1] This is a schematic diagram of the structure of the present invention. [Figure 2] This is a cross-sectional view of the present invention. [Figure 3] This is an enlarged schematic diagram of section A in Figure 2. [Figure 4] Figure 2 shows a schematic diagram of the assembly of the two magnetic rings, the first annular support, and the second annular support. [Figure 5] Figure 2 is a schematic diagram of the mounting panel structure. [Modes for carrying out the invention]

[0018] The present invention will be further described below with reference to the drawings and specific embodiments.

[0019] Referring to Figures 1-5, a rotational speed detection structure for an actuator according to the present invention is shown. The rotational speed detection structure includes a housing 10, a motor 20, and a reduction mechanism, the motor 20 and the reduction mechanism being mounted inside the housing 10. The reduction mechanism is a harmonic reducer 60, and the motor 20 includes a stator 22 and a rotor 21. The stator 22 is fixedly engaged with the housing 10, and the rotor 21 surrounds the outer circumference of the stator 22 and fits the stator 22, thereby the rotor 21 and stator 22 forming a frameless torque motor. An axle sleeve 40 is synchronously connected to the rotor 21, and the input end of the harmonic reducer 60 is connected to the rotor 21. That is, the web generator 62 of the harmonic reducer 60 is connected to the rotor 21. The flex spline 63 of the harmonic reducer 60 is the output end, to which an encoder shaft 30 is connected. The encoder shaft 30 is inserted inside the axle sleeve 40 and is mounted coaxially with the axle sleeve 40. The encoder shaft 30 is pivotably mounted to the housing 10 and extends upward from the lower end of the actuator, passing through the entire axial direction of the actuator to the top of the actuator. The encoder shaft 30 is provided with a first mounting surface 311, and the shaft sleeve 40 is provided with a second mounting surface 411. A first magnetic ring 81 is fixedly connected to the first mounting surface 311, and a second magnetic ring 82 is fixedly connected to the second mounting surface 411. The first magnetic ring 81 and the second magnetic ring 82 are at the same height or approximately the same height, and the central axes of the first magnetic ring 81 and the second magnetic ring 82 coincide with the central axis of the encoder shaft 30. A PCB board 50 is fixed to the housing 10, and the PCB board 50 has a third mounting surface 501 that faces the first mounting surface 311 and the second mounting surface 411. A first Hall element and a second Hall element are mounted on the third mounting surface 501. The first Hall element fits into the first magnetic ring 81, and the first Hall element works in cooperation with the first magnetic ring 81 to detect the rotation angle of the first magnetic ring 81, thereby obtaining the angle of the encoder shaft 30, and thereby obtaining the angle of the actuator's output end (i.e., the low-speed end).On the one hand, the second Hall element is adapted to the second magnetic ring 82, and the second Hall element cooperates with the second magnetic ring 82 to detect the rotation angle of the second magnetic ring 82 to obtain the angle of the shaft sleeve 40, thereby obtaining the angle of the rotor 21 of the motor 20 (i.e., the high-speed end).

[0020] Taking the first Hall element and the first magnetic ring 81 as an example, the two cooperate with each other, the first Hall element detects the change of the magnetic field when the first magnetic ring 81 rotates, and calculates the angle information, whereby the absolute rotation angle of the first magnetic ring can be obtained. The Hall element usually detects the angular velocity of the magnetic ring by a pulse counting method, where ω=2πf / N (ω is the angular velocity, f is the pulse frequency, and N is the number of pole pairs of the magnetic ring), and further, the absolute rotation angle of the magnetic ring is calculated using the angular velocity. The process for the Hall element to cooperate with the magnetic ring to obtain parameters such as the rotation angle and angular velocity of the magnetic ring is well known to those skilled in the art, and will not be described in detail here.

[0021] In other embodiments, the first Hall element and the first magnetic ring 81 may cooperate to detect the rotation speed of the first magnetic ring 81 to obtain the angular velocity of the encoder shaft 30, and based on this, the angle or angular velocity of the low-speed end may be obtained. The second Hall element and the second magnetic ring 82 may cooperate to detect the rotation speed of the second magnetic ring 82 to obtain the angular velocity of the shaft sleeve 40, and based on this, the angle or angular velocity of the rotor 21 of the motor 20 (i.e., the high-speed end) may be obtained.

[0022] The encoder shaft 30 and the shaft sleeve 40 that are fitted to each other are respectively provided with a first mounting surface 311 for mounting the first magnetic ring 81 and a second mounting surface 411 for mounting the second magnetic ring 82, so that the first magnetic ring 81 and the second magnetic ring 82 can be arranged at the same position or substantially the same position in the axial direction of the actuator. Therefore, only by installing one PCB substrate 50 in the housing 10, two Hall elements respectively adapted to the two magnetic rings can be mounted, that is, the Hall elements corresponding to the two magnetic rings can share the same PCB substrate. As a result, the internal structure of the actuator is simplified, the integration degree inside the actuator is improved, which is beneficial to the optimization of the space inside the actuator. In addition, the low-speed end detection and the high-speed end detection of the actuator can be concentrated in the same area inside the actuator, which facilitates the layout of internal wiring.

[0023] The speed reduction mechanism of the present invention is not limited to the above-mentioned harmonic speed reducer 60, and the speed reduction mechanism may be a planetary speed reducer or an RV speed reducer. As the motor 20, a frameless torque motor with a built-in rotor can be used. Further, motors of other structural forms may also be used.

[0024] A first annular support 31 is fixed to the encoder shaft 30 in a detachable manner, and a second annular support 41 surrounding the outer periphery of the first annular support 31 is fixed to the shaft sleeve 40 in a detachable manner. The upper surface of the first annular support 31 forms the first mounting surface 311, and the upper surface of the second annular support 41 forms the second mounting surface 411. In this preferred embodiment, the first annular support 31 and the second annular support 41 are respectively detachably fixed to the encoder shaft 30 and the shaft sleeve 40, and the first magnetic ring 81 and the second magnetic ring 82 are respectively installed on the first annular support 31 and the second annular support 41, whereby the assembly and inspection of the actuator can be facilitated.

[0025] Furthermore, a mounting base 32 is fitted onto the encoder shaft 30, and a tightening screw 33 is screwed into the mounting base 32. The tightening screw 33 extends along the radial direction of the encoder shaft 30, and its inner end is fitted into a screw hole provided in the encoder shaft 30. A male screw is provided on the outer edge of the mounting base 32, and a female screw is provided on the inner edge of the first annular support 31, and the first annular support 31 is fixed to the outer edge of the mounting base 32 by the fitting of the female screw and the male screw. By installing the mounting base 32 on the encoder shaft 30, the portion of the encoder shaft 30 for attaching the first annular support 31 has a relatively large outer diameter, and since the diameter of the encoder shaft 30 is smaller than the diameter of the shaft sleeve 40, after increasing the diameter with the mounting base 32, the first annular support 31 can be brought as close as possible to the second annular support 41 in the radial direction of the actuator. This allows the first mounting surface 311 to be brought closer to the second mounting surface 411, making it possible to relatively reduce the radial distance between the first magnetic ring 81 and the second magnetic ring 82 of the actuator. As a result, the mounting requirements for two Hall elements can be met with only a small PCB substrate 50, further reducing the space occupied by the PCB substrate 50, which is advantageous for optimizing the internal space of the actuator.

[0026] The second annular support 41 described above may be fixed to the shaft sleeve 40 by a screw fitting method. Specifically, a male thread is provided on the upper part of the outer edge surface of the shaft sleeve 40, and a female thread is provided on the inner edge of the second annular support 41, and the second annular support 41 is screwed onto the upper part of the shaft sleeve 40 by fitting the female thread and the male thread. In the present invention, the first annular support 31 is removably fixed to the encoder shaft 30 or the fixing base 32 of the encoder shaft 30 by the threaded portion, and the second annular support 41 is removably fixed to the shaft sleeve 40 by the threaded portion. During assembly, the first magnetic ring 81 and the first annular support 31 are assembled as an assembly, and the second magnetic ring 82 and the second annular support 41 are assembled as an assembly, and the two assemblies are assembled to the encoder shaft 30 and the shaft sleeve 40, respectively, from the top to the bottom of the actuator. Next, a PCB board 50 having two Hall elements is placed below the first annular support 31 and the second annular support 41, ensuring that the two Hall elements correspond to the two magnetic rings. This makes the assembly of the actuator simple and easy.

[0027] To further optimize the axial space of the actuator, a first annular groove 312 recessed downwards is provided on the upper surface of the first annular support 31, and the first magnetic ring 81 is fitted into the first annular groove 312. The thickness of the first magnetic ring 81 is the same as the depth of the first annular groove 312, so that the first magnetic ring 81 does not protrude from the upper surface of the first annular support 31. Similarly, a second annular groove 412 recessed downwards is provided on the upper surface of the second annular support 41, and the second magnetic ring 82 is fitted into the second annular groove 412. The thickness of the second magnetic ring 82 is the same as the thickness of the second annular groove 412, so that the second magnetic ring 82 does not protrude from the upper surface of the second annular support 41. The upper surfaces of the first annular support 31 and the second annular support 41 are flush, and when combined with the above structure, the upper surfaces of the first magnetic ring 81 and the second magnetic ring 82 are flush. By mounting the first magnetic ring 81 and the second magnetic ring 82 in a manner that they are recessed into the upper surfaces of the first annular support 31 and the second annular support 41, respectively, the gap between the first annular support 31 and the second annular support 41 and the PCB substrate 50 can be made relatively small. Furthermore, since the two magnetic rings are offset from each other in the radial direction of the actuator, and the upper surfaces of the two magnetic rings are provided to be flush with the axial direction of the actuator, the space occupied by the entire rotational speed detection structure in the axial direction of the actuator can be further reduced.

[0028] In addition, in this invention, the first mounting surface 311 may be directly provided on the encoder shaft 30, and the second mounting surface 411 may be directly provided on the shaft sleeve 40.

[0029] The housing 10 includes an outer wall 11, an upper wall 12, and a support wall 13. The upper wall 12 extends inward from the top of the outer wall 11 along the radial direction of the actuator, and the support wall 13 extends downward from the inner edge of the upper wall 12. A mounting space is formed between the support wall 13 and the outer wall 11, and the motor 20 is positioned within this mounting space. The stator 22 of the motor 20 is fixedly fitted onto the outer circumference of the support wall 13, the rotor 21 is positioned between the stator 22 and the outer wall 11 and surrounds the outer circumference of the stator 22, and the PCB board 50 is fixedly connected to the upper wall 12, thereby fixing the PCB board 50 to the housing 10 and locating above the first mounting surface 311 and the second mounting surface 411. The outer wall 11, the upper wall 12, and the support wall 13 form a U-shaped cross-sectional structure in the housing 10, providing a mounting space for the motor 20 and serving to provide better protection for the motor 20. Furthermore, the upper wall 12 can be used to provide a mounting base for the PCB board 50, making it easier to install the PCB board 50.

[0030] To further improve ease of installation, a mounting plate 14 is fixedly connected to the upper wall 12, and an annular rib 141 protruding upward is provided on the upper surface of the mounting plate 14. The outer edge of the PCB substrate 50 is circular, and the PCB substrate 50 is placed on the upper surface of the mounting plate 14, with its outer edge in contact with the inner edge of the annular rib 141. The annular rib 141 is used to position the PCB substrate 50 in the radial direction of the actuator, and two Hall elements pre-attached to the PCB substrate 50 can be aligned with two magnetic rings in the radial direction of the actuator. This improves the mounting accuracy of the PCB substrate 50 and ensures that the detection of the low-speed and high-speed ends of the actuator has high accuracy.

[0031] The harmonic reducer 60 described above includes a web generator 62, a circular spline 61, and a flex spline 63. The circular spline 61 is fixedly engaged with the housing 10, and the web generator 62 is connected to the bottom of the rotor 21 via a connecting bracket 23. An output flange 64 is fixed to the flex spline 63, and the output flange 64 is pivotally attached via a bearing 71 to a lower housing 70 which is fixedly connected to the housing 10. The circular spline 61 may also be clamped and fixed between the lower housing 70 and the housing 10, thereby allowing the circular spline 61 to be fixedly engaged with the housing 10. The bottom of the encoder shaft 30 is fixedly connected to the output flange 64 by bolts. A fixing bracket 15 is fixedly connected above the upper wall 12, and the upper part of the encoder shaft 30 is pivotally attached to the fixing bracket 15 via a bearing 16. In this configuration, both the upper and lower ends of the encoder shaft 30 are pivotally attached to the housing 10 via bearings 16 and 71, respectively. The bearings 16 and 71 provide radial support to the encoder shaft 30, thereby stabilizing its rotation. As a result, the accuracy of detection at the low-speed end is improved.

[0032] The lower end of the shaft sleeve 40 is fixedly connected to the connecting bracket 23 by bolts, thereby synchronously connecting the shaft sleeve 40 and the rotor 21. The shaft sleeve 40 is located inside the support wall 13 and is pivotally mounted to the support wall 13 via a bearing 42. The support wall 13 and the bearing 42 are used to provide radial support to the shaft sleeve 40, making the rotation of the shaft sleeve 40 more stable and improving the accuracy of high-speed end detection.

[0033] The actuator of the present invention includes a rotational speed detection structure for the actuator described above. Other structures of the actuator are the same as those of the prior art and will not be described in detail here.

Claims

1. An actuator rotation speed detection structure, comprising a housing, a motor, and a reduction mechanism, The motor includes a stator that is fixedly engaged with the housing, and a rotor that fits the stator and is rotatable relative to the stator. The rotor is synchronously connected to an axis sleeve that is pivotally mounted to the housing, the input terminal of a reduction mechanism is connected to the rotor, and the output terminal of the reduction mechanism is connected to an encoder shaft that is inserted into the axis sleeve and mounted coaxially with the axis sleeve. An actuator rotation speed detection structure characterized in that: the encoder shaft is provided with a first mounting surface; the shaft sleeve is provided with a second mounting surface; in the radial direction of the actuator, the second mounting surface is located outside the first mounting surface; a first magnetic ring is fixed to the first mounting surface; a second magnetic ring is fixed to the second mounting surface; the central axes of the first and second magnetic rings coincide with the central axis of the encoder shaft; a PCB substrate is fixed to the housing; the PCB substrate includes a third mounting surface directly facing the first and second mounting surfaces; a first Hall element and a second Hall element are mounted on the third mounting surface; the first Hall element cooperates with the first magnetic ring to detect the rotation angle of the first magnetic ring and thereby obtain the angle of the encoder shaft; and the second Hall element cooperates with the second magnetic ring to detect the rotation angle of the second magnetic ring and thereby obtain the angle of the shaft sleeve.

2. Including a housing, motor, and reduction mechanism, The motor includes a stator that is fixedly engaged with the housing, and a rotor that fits the stator and is rotatable relative to the stator. The rotor is synchronously connected to an axis sleeve that is pivotally mounted to the housing, the input terminal of a reduction mechanism is connected to the rotor, and the output terminal of the reduction mechanism is connected to an encoder shaft that is inserted into the axis sleeve and mounted coaxially with the axis sleeve. An actuator rotation speed detection structure characterized in that: the encoder shaft is provided with a first mounting surface; the shaft sleeve is provided with a second mounting surface; in the radial direction of the actuator, the second mounting surface is located outside the first mounting surface; a first magnetic ring is fixed to the first mounting surface; a second magnetic ring is fixed to the second mounting surface; the central axes of the first and second magnetic rings coincide with the central axis of the encoder shaft; a PCB substrate is fixed to the housing; the PCB substrate includes a third mounting surface directly facing the first and second mounting surfaces; a first Hall element and a second Hall element are mounted on the third mounting surface; the first Hall element works in cooperation with the first magnetic ring to detect the rotation speed of the first magnetic ring and thereby obtain the angular velocity of the encoder shaft; and the second Hall element works in cooperation with the second magnetic ring to detect the rotation speed of the second magnetic ring and thereby obtain the angular velocity of the shaft sleeve.

3. The actuator rotation speed detection structure according to claim 1 or 2, characterized in that a first annular support is fixed to the encoder shaft in a removable manner, a second annular support surrounding the outer circumference of the first annular support is fixed to the shaft sleeve in a removable manner, the upper surface of the first annular support forms a first mounting surface, and the upper surface of the second annular support forms a second mounting surface.

4. The rotational speed detection structure for an actuator according to claim 3, characterized in that the upper surface of the first annular support is provided with a first annular groove recessed downward, the first magnetic ring has a thickness equal to the depth of the first annular groove and is fitted into the first annular groove, the upper surface of the second annular support is provided with a second annular groove recessed downward, the second magnetic ring has a thickness equal to the depth of the second annular groove and is fitted into the second annular groove, and the upper surfaces of the first magnetic ring and the second magnetic ring are flush.

5. The actuator rotation speed detection structure according to claim 3, characterized in that a fixed base is fitted onto the encoder shaft, a tightening screw is screwed into the fixed base, the inner end of the tightening screw is fitted into a screw hole provided on the encoder shaft, and the first annular support is fitted onto the fixed base and screw-fitted to the fixed base.

6. The rotational speed detection structure for an actuator according to claim 3, characterized in that the second annular support is fitted onto the upper part of the shaft sleeve and screw-fitted to the shaft sleeve.

7. The rotational speed detection structure for an actuator according to claim 1 or 2, characterized in that the housing includes an outer wall, an upper wall extending inward from the top of the outer wall along the radial direction of the actuator, and a support wall extending downward from the inner edge of the upper wall, a mounting space formed between the support wall and the side wall, the motor being placed in the mounting space, the stator being fixedly connected to the outer circumference of the support wall, the rotor surrounding the outer circumference of the stator, and the PCB substrate being fixedly connected to the upper wall so as to be located above the first mounting surface and the second mounting surface.

8. The actuator rotation speed detection structure according to claim 7, characterized in that a mounting plate is fixedly connected to the upper part of the upper wall, an annular rib protruding upward is provided on the upper surface of the mounting plate, and the outer edge of the PCB substrate is circular and abuts against the inner edge of the annular rib.

9. The rotational speed detection structure for an actuator according to claim 7, characterized in that the reduction mechanism is a harmonic reducer, the circular spline of the harmonic reducer is fixedly engaged with the housing, the web generator of the harmonic reducer is connected to the bottom of the rotor via a connecting bracket, an output flange pivotally attached to the housing via a bearing is fixed to the flex spline of the harmonic reducer, the bottom of the encoder shaft is fixedly connected to the output flange, a fixing bracket is fixedly connected above the upper wall, and the upper part of the encoder shaft is pivotally attached to the fixing bracket via a bearing.

10. The rotational speed detection structure for an actuator according to claim 9, characterized in that the lower end of the shaft sleeve is fixedly connected to a connecting bracket by a bolt, thereby synchronously connecting the shaft sleeve and the rotor, and the shaft sleeve is located inside the support wall and pivotally mounted to the support wall via a bearing.

11. An actuator, characterized by including a rotational speed detection structure for the actuator according to any one of claims 1 to 10.

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