A servo motor

Abstract

A servo motor relates to the technical field of motor, including: rotor assembly, the rotor assembly includes motor shaft; encoder assembly, including magnetic steel, circuit board, the magnetic steel is fixed on the end face of the first end of the motor shaft through the support, the circuit board is equipped with first magnetic induction element, second magnetic induction element, first magnetic induction element, second magnetic induction element are respectively equipped on the opposite two faces of circuit board, and all with magnetic steel corresponds, to make first magnetic induction element, second magnetic induction element synchronous detection to the magnetic steel.Working first magnetic induction element, second magnetic induction element can synchronous detection to magnetic steel, thus can obtain two groups of monitoring data, be favorable to improve the reliability of monitoring data, and when one of the encoder fails, the other encoder can also monitor, be favorable to improve the stability of motor operation, and only need to install a magnetic steel on the motor shaft, will not extra lengthen the axial length of motor shaft.

Description

Technical Field

[0001] This application relates to the field of motor technology, specifically to a servo motor. Background Technology

[0002] A servo motor is an electric motor capable of controlling its position, speed, and acceleration. It achieves precise, rapid, and stable motion control by receiving command signals from a control system. A servo motor includes an encoder, which monitors the motor's rotational position and speed. Typically, only one encoder is used; a single encoder provides limited data, has low reliability, and will malfunction if it fails, affecting the motor's operational stability. Utility Model Content

[0003] This application provides a servo motor that can solve the problems of single data and low reliability of encoder monitoring.

[0004] According to one aspect of this application, one embodiment provides a servo motor, comprising:

[0005] Rotor assembly, the rotor assembly including a motor shaft;

[0006] The encoder assembly includes a magnet and a circuit board. The magnet is fixed to the end face of the first end of the motor shaft by a support member. The circuit board is provided with a first magnetic induction element and a second magnetic induction element. The first magnetic induction element and the second magnetic induction element are respectively provided on two opposite sides of the circuit board and are both corresponding to the magnet, so that the first magnetic induction element and the second magnetic induction element can detect the magnet synchronously.

[0007] In one embodiment, the first magnetic induction element, the second magnetic induction element, and the magnet are arranged coaxially.

[0008] In one embodiment, the end face of the first end is provided with an assembly groove, the magnet is fixed on the support member, the outer contour of the cross-section of the support member is circular, the cross-section is a section perpendicular to the axial direction of the motor shaft, and the support member is fixed in the assembly groove to fix the magnet on the end face of the first end.

[0009] In one embodiment, the maximum dimension of the magnet in the direction perpendicular to the motor shaft axis is greater than or equal to the diameter of the first end. The support member is in the shape of a stepped shaft and includes a small diameter section and a large diameter section. The magnet is fixed to the end face of the large diameter section, and the small diameter section is fixed in the assembly groove to fix the large diameter section and the magnet to the outside of the first end.

[0010] Alternatively, the maximum dimension of the magnet in the direction perpendicular to the motor shaft axis is smaller than the diameter of the first end, the support member is cylindrical, and the cylindrical support member is fixed in the assembly groove to fix the magnet in the first end.

[0011] In one embodiment, the servo motor further includes a housing and a stator. The housing includes a main body and a front cover and a rear cover respectively connected to opposite ends of the main body. The stator is disposed within the housing and has an assembly hole. The rotor assembly is disposed in the assembly hole, and the circuit board is mounted on the rear cover. The rear cover has a first support portion protruding towards the side of the main body. At least a portion of the first support portion is located in the assembly hole, and the first end is supported on the first support portion by a bearing.

[0012] In one embodiment, the encoder assembly further includes a bracket, the circuit board is fixed on the bracket, the rear end cover has a receiving cavity, the bottom of the receiving cavity has a groove, the bracket is located in the groove and fixedly connected to the rear end cover to support the circuit board in the receiving cavity, and the bottom of the groove has a through hole for the magnetic induction element to sense the magnet.

[0013] In one embodiment, the bracket is plate-shaped and fits against the bottom of the groove. The circuit board is fixed to the side of the bracket away from the through hole. The bottom of the groove is provided with a threaded hole. Screws pass through the circuit board, and the bracket engages with the threaded hole to fix the circuit board, the bracket, and the rear end cover into one unit.

[0014] In one embodiment, the motor shaft includes a main body section and a mounting section. The mounting section is located at one end of the motor shaft. The diameter of the mounting section is smaller than the diameter of the main body section. The mounting section is supported on the first support portion by the bearing. The axial length of the mounting section is greater than or equal to the axial length of the bearing, and the difference between the two is less than or equal to 1 mm.

[0015] In one embodiment, the rotor assembly includes a rotor core fixed to the motor shaft, the end face of the rotor core and the wall of the mounting hole enclose a receiving space located in the mounting hole, and at least a portion of the first support is located in the receiving space.

[0016] In one embodiment, the front end cover is provided with a second support portion protruding towards the side of the main body, and the two ends of the motor shaft are respectively supported on the first support portion and the second support portion by bearings.

[0017] According to the servo motor of the above embodiment, the first magnetic induction element and the second magnetic induction element are respectively disposed on two opposite sides of the circuit board, and each corresponds to a magnet. During operation, the first magnetic induction element and the second magnetic induction element can simultaneously detect the magnet, thereby obtaining two sets of monitoring data, which helps to improve the reliability of the monitoring data. Moreover, if one encoder fails, the other encoder can still monitor, which helps to improve the stability of motor operation. At the same time, only one magnet needs to be installed on the motor shaft, without additionally extending the axial length of the motor shaft. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a servo motor according to one embodiment;

[0019] Figure 2 This is a partial structural schematic diagram of a servo motor according to one embodiment;

[0020] Figure 3 This is a schematic diagram of a support structure disposed in a groove according to one embodiment;

[0021] Figure 4 This is a schematic diagram of the structure of the rear end cover in one embodiment;

[0022] Figure 5 This is a schematic diagram of the structure of a circuit board according to one embodiment;

[0023] Explanation of reference numerals in the attached figures:

[0024] 1-Support component; 101-Exhaust port; 2-First magnetic induction element; 3-Motor shaft; 301-Mounting section; 302-Main body section; 4-Stator; 401-Assembly hole; 5-Rotor core; 6-Second magnetic induction element; 7-Front end cover; 701-Second support part; 8-Main body part; 9-Rear end cover; 901-First support part; 902-Groove; 903-Through hole; 904-Receiving cavity; 10-Bearing; 11-Magnet; 12-Circuit board; 13-Bracket. Detailed Implementation

[0025] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments. Similar elements in different embodiments are referred to by related similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of the present application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to the present application are not shown or described in the specification. This is to avoid obscuring the core parts of the present application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0026] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0027] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the objects being described and have no sequential or technical meaning. Unless otherwise specified, the terms "connection" and "linkage" used in this application include both direct and indirect connections (linkages).

[0028] Servo motors include encoders, which are used to monitor the motor's rotational position and speed. Typically, only one encoder is used. A single encoder provides limited data, has low reliability, and will malfunction if it fails, affecting the motor's operational stability.

[0029] This application places the first magnetic induction element and the second magnetic induction element on opposite sides of the circuit board, each corresponding to a magnet. During operation, the first and second magnetic induction elements can simultaneously detect the magnet, thereby obtaining two sets of monitoring data, which helps improve the reliability of the monitoring data. Furthermore, if one encoder fails, the other encoder can still monitor, which helps improve the stability of motor operation. At the same time, only one magnet needs to be installed on the motor shaft, without additionally extending the axial length of the motor shaft.

[0030] Please see Figures 1 to 5 This application provides a servo motor, including a rotor assembly, an encoder assembly, and other functional components as needed, which are described in detail below.

[0031] The rotor assembly in this embodiment includes a motor shaft 3; the encoder assembly includes a magnet 11 and a circuit board 12. The magnet 11 is fixed to the end face of the first end of the motor shaft 3 by a support member 1. The circuit board 12 is provided with a first magnetic induction element 2 and a second magnetic induction element 6. The first magnetic induction element 2 and the second magnetic induction element 6 are respectively provided on two opposite surfaces of the circuit board 12 and are both corresponding to the magnet 11, so that the first magnetic induction element 2 and the second magnetic induction element 6 can detect the magnet 11 synchronously.

[0032] It is understood that in this embodiment, the magnet 11 is fixed to the motor shaft 3 and rotates together with the motor shaft 3. Therefore, the motion data of the monitored magnet 11 is also the motion data of the rotation of the motor shaft 3, and this motion data can be used for system servo control. The magnet 11 is fixed to the support member 1, which has the function of supporting and positioning. The support member 1 can be made of a non-magnetic material, such as aluminum alloy or copper alloy. The non-magnetic support member 1 also has an isolation function. Figure 5 As shown, the first magnetic sensing element 2 and the second magnetic sensing element 6 are respectively disposed on two opposite surfaces of the circuit board 12, and both correspond to the magnet 11. For example, the first magnetic sensing element 2 and the second magnetic sensing element 6 can be disposed on the side of the circuit board 12 closest to the magnet 11 and the side furthest from the magnet 11, respectively. The circuit board 12 allows magnetic lines of force to pass through, thereby enabling the magnetic sensing element located on the surface of the circuit board 12 furthest from the magnet 11 to also sense changes in the magnetic field. This allows both magnetic sensing elements located on opposite surfaces of the circuit board 12 to detect the magnet 11. In some applications, the first magnetic sensing element 2 and the second magnetic sensing element 6 can also be disposed on the same surface of the circuit board 12, and the first magnetic sensing element 2 and the second magnetic sensing element 6 can be overlapped.

[0033] In the servo motor provided in this embodiment, the first magnetic induction element 2 and the second magnetic induction element 6 are respectively disposed on two opposite sides of the circuit board 12, and both correspond to the magnet 11. During operation, the first magnetic induction element 2 and the second magnetic induction element 6 can simultaneously detect the magnet 11, thereby obtaining two sets of monitoring data, which helps to improve the reliability of the monitoring data. Moreover, if one encoder fails, the other encoder can still monitor, which helps to improve the stability of the motor operation. At the same time, only one magnet 11 needs to be installed on the motor shaft 3, without additionally extending the axial length of the motor shaft 3.

[0034] In one embodiment, such as Figure 1 , Figure 2As shown, the first magnetic induction element 2, the second magnetic induction element 6, and the magnet 11 can be arranged coaxially. In this embodiment, the coaxial line means that the central axes of the first magnetic induction element 2, the second magnetic induction element 6, and the magnet 11 coincide. In some embodiments, the central axes of the first magnetic induction element 2, the second magnetic induction element 6, and the magnet 11 can coincide with the central axis of the motor shaft 3. In some application scenarios, the central axes of the first magnetic induction element 2, the second magnetic induction element 6, and the magnet 11 may be misaligned due to assembly errors. Arranging them coaxially helps improve the detection accuracy of the first magnetic induction element 2 and the second magnetic induction element 6.

[0035] In one embodiment, the end face of the first end of the motor shaft 3 is provided with an assembly groove. The magnet 11 is fixed on the support member 1. The outer contour of the cross-section of the support member 1 is circular, and the cross-section is perpendicular to the axial direction of the motor shaft 3. The support member 1 is fixed in the assembly groove to fix the magnet 11 to the end face of the first end. The support member 1 is fixed in the assembly groove of the motor shaft 3 without occupying the outer peripheral sidewall of the motor shaft 3. The magnet 11 of the encoder can be installed without extending the motor shaft 3, which is beneficial to shortening the length of the motor shaft 3 and reducing the overall axial length of the motor. The outer contour of the cross-section of the support member 1 is circular, which is beneficial to improving the rotational balance of the motor shaft 3. When the outer contour of the cross-section of the support member 1 is circular, the shape of the assembly groove can also be a circular groove, and the size of the assembly groove can match the size of the small diameter section. In some embodiments, the outer contour of the cross-section of the support member 1 can also be rectangular or other shapes.

[0036] In one embodiment, when the maximum dimension of the magnet 11 in the direction perpendicular to the axis of the motor shaft 3 is greater than or equal to the diameter of the first end of the motor shaft 3, the support member 1 is in the form of a stepped shaft. The support member 1 includes a small-diameter section and a large-diameter section. The magnet 11 is fixed to the end face of the large-diameter section, and the small-diameter section is fixed in the mounting groove to fix the large-diameter section and the magnet 11 to the outside of the first end of the motor shaft 3. In this embodiment, the maximum width of the magnet 11 in the direction perpendicular to the axis of the motor shaft 3 is the maximum width value of the magnet 11 in the radial direction of the motor shaft 3. For example, when the outer contour of the magnet 11 is circular, the maximum width of the magnet 11 in the direction perpendicular to the axis of the motor shaft 3 is the outer diameter value of the outer contour of the magnet 11. When the maximum width of the magnet 11 in the direction perpendicular to the axis of the motor shaft 3 is greater than or equal to the diameter of the first end of the motor shaft 3, the small-diameter section of the support member 1 is fixed in the mounting groove, which does not require occupying the outer peripheral mounting surface of the end of the motor shaft 3, thus helping to reduce the axial length of the motor shaft 3. In one embodiment, when the maximum dimension of the magnet 11 in the direction perpendicular to the axis of the motor shaft 3 is smaller than the diameter of the first end of the motor shaft 3, the support member 1 is cylindrical. The cylindrical support member 1 is fixed in the assembly groove to fix the magnet 11 inside the first end of the motor shaft 3. Fixing the support member 1 entirely in the assembly groove also helps to reduce the axial length of the motor shaft 3. In some embodiments, the magnet 11 can be embedded in the support member 1, and the end face of the magnet 11 is flush with or almost flush with the end face of the first end of the motor shaft 3, which can further reduce the overall axial length of the motor.

[0037] In one embodiment, the support member 1 is fixed in the assembly groove by an interference fit. The support member 1 has a through vent hole 101, which allows the end face of the support member 1 to fit against the bottom of the assembly groove during assembly by venting air through the vent hole 101. The interference fit of the support member 1 in the assembly groove makes assembly simple and quick. The vent hole 101 on the support member 1 discharges air between the support member 1 and the bottom of the assembly groove during the assembly process, allowing the end face of the support member 1 to fit against the bottom of the assembly groove, increasing the reliability of the connection. In some embodiments, the support member 1 can also be fixed in the assembly groove by other means, such as adhesive bonding.

[0038] In one embodiment, such as Figure 1 , Figure 2As shown, the servo motor also includes a housing and a stator 4. The housing includes a main body 8 and a front cover 7 and a rear cover 9 respectively connected to opposite ends of the main body 8. The stator 4 is disposed inside the housing and has an assembly hole 401. The rotor assembly is disposed in the assembly hole 401, and the circuit board 12 is mounted on the rear cover 9. The rear cover 9 has a first support portion 901 protruding towards the side near the main body 8. At least a portion of the first support portion 901 is located in the assembly hole 401, and the first end of the motor shaft 3 is supported on the first support portion 901 by a bearing. The housing can be metal or plastic. In this embodiment, the connection between the front cover 7, the rear cover 9 and the main body 8 is not specifically limited, and can be fixed by means of, but not limited to, screw connection. In this embodiment, the assembly hole 401 of the stator 4 is a hole structure for assembling the rotor assembly. The stator 4 includes a stator core and windings disposed on the stator core. An insulating sleeve can also be disposed on the stator core. The stator core has an inner hole, and the assembly hole 401 can be formed by a combination of the inner hole of the stator core and the circular hole formed by the insulating sleeve. At least a portion of the first support portion 901 is located in the mounting hole 401, thereby allowing the bearing support position at the end of the motor shaft 3 to move inward, which in turn allows the first end of the motor shaft 3 to move inward, shortening the axial length of the motor shaft 3. This embodiment does not limit the specific structure of the first support portion 901; for example, it can be a cylindrical axial protrusion, or a rectangular or other shaped protrusion. To ensure good load-bearing capacity of the first support portion 901, a tapered transition section can be provided at the end of the first support portion 901 away from the motor shaft 3. The tapered transition section prevents stress concentration at the end of the first support portion 901.

[0039] In one embodiment, such as Figure 3 , Figure 4 The encoder assembly also includes a bracket 13, on which the circuit board 12 is fixed. The rear end cover 9 has a receiving cavity 904, with a groove 902 at its bottom. The bracket 13 is located in the groove 902 and fixedly connected to the rear end cover 9 to support the circuit board 12 within the receiving cavity 904. The bottom of the groove 902 has a through hole 903 for the magnetic sensing element's sensing magnet 11. The groove 902 at the bottom of the receiving cavity 904, where the bracket 13 is located, positions the bracket 13, improving its assembly accuracy and increasing the encoder's monitoring accuracy. Since the bracket 13 is fixed in the groove 902, the receiving cavity 904 can accommodate the circuit board 12, reducing its depth and thus the axial length of the motor. In some embodiments, the bracket 13 may also be fixed to the bottom of the receiving cavity 904.

[0040] In one embodiment, the bracket 13 is plate-shaped and fits into the bottom of the groove 902. The circuit board 12 is fixed on the side of the bracket 13 away from the through hole 903. The bottom of the groove 902 has a threaded hole. Screws pass through the circuit board 12, and the bracket 13 engages with the threaded hole to fix the circuit board 12, bracket 13, and rear end cover 9 into a single unit. In this embodiment, the plate-shaped bracket 13 provides good support for the circuit board 12, and the plate-shaped bracket 13 is relatively thin, which helps to reduce the axial length. The circuit board 12, bracket 13, and rear end cover 9 are fixed into a single structure by screws, which helps to reduce assembly steps, improve the integration of the motor, and also helps to improve assembly accuracy, thereby improving the detection accuracy of the encoder. In some embodiments, the circuit board 12 can also be fixed to the bracket 13 by screws, and the bracket 13 is fixed in the groove 902 by snap-fit. In some embodiments, a positioning post can also be provided on the bracket 13. The positioning post is inserted into the positioning hole provided on the circuit board 12 to position the circuit board 12. In this embodiment, the material of the bracket 13 is not specifically limited; it can be metal or plastic.

[0041] In one embodiment, such as Figure 1 , Figure 2As shown, the motor shaft 3 includes a main body section 302 and a mounting section 301. The mounting section 301 is located at one end of the motor shaft 3. The diameter of the mounting section 301 is smaller than the diameter of the main body section 302. The mounting section 301 is supported on the first support portion 901 by a bearing 10. The axial length of the mounting section is greater than or equal to the axial length of the bearing, and the difference between the two is less than or equal to 1 mm. In this embodiment, the diameter of the mounting section 301 is smaller than the diameter of the main body section 302, thereby forming a step between the main body section 302 and the mounting section 301. This step can provide axial restraint for the bearing 10. The axial length of the mounting section 301 is greater than or equal to the axial length of the bearing 10, which can provide good support for the motor shaft 3. Moreover, the difference between the axial length of the mounting section 301 and the axial length of the bearing 10 is less than or equal to 1 mm. That is, the length of the mounting section 301 can be reduced to approximately the same length as the axial length of the bearing 10, and the motor shaft 3 does not need to be extended to install the magnet 11. The magnet 11 is placed in the mounting groove on the end face of the mounting section 301, so that the support member 1 does not occupy the outer peripheral mounting surface of the motor shaft 3 end. The outer peripheral mounting surface of the motor shaft 3 end can be used only for mounting the bearing 10. After the support member 1 is installed in the mounting groove, the support member 1 is also inserted into the inner hole of the bearing 10, reducing the axial dimension. In some embodiments, in order to make the axial length of the motor shaft 3 sufficiently small while still providing good support for the motor shaft 3, the difference between the axial length of the mounting section 301 and the axial length of the bearing 10 can be selected to be 8 mm. In some embodiments, the axial length of the mounting section 301 can also be slightly smaller than the axial length of the bearing 10, and the difference between the axial length of the mounting section 301 and the axial length of the bearing 10 can also be greater than 1 mm. In some application scenarios, the diameter of the mounting section 301 can also be greater than or equal to the diameter of the main body section 302. In this case, a limiting flange can be provided between the mounting section 301 and the main body section 302 to limit the bearing 10.

[0042] In one embodiment, the rotor assembly includes a rotor core 5, which is fixed to the motor shaft 3. The end face of the rotor core 5 and the wall of the mounting hole 401 enclose a receiving space within the mounting hole 401. At least a portion of the first support portion 901 is located within this receiving space. The rotor core 5 is located within the mounting hole 401 of the stator 4. Typically, the rotor core 5 does not protrude from the mounting hole 401 of the stator 4; that is, there is a gap between the end face of the rotor core 5 and the end face of the stator 4, which forms the receiving space. By providing the first support portion 901 on the rear end cover 9, which extends into the receiving space, not only can the motor structure be made more compact, but the axial length of the motor can also be reduced without modifying the stator 4 or the rotor structure, thus saving manufacturing costs. In some embodiments, the structure of the stator 4 or the rotor can also be improved to create space for accommodating the first support portion 901.

[0043] In one embodiment, the front cover 7 has a second support portion 701 protruding towards the side near the main body 8. Both ends of the motor shaft 3 are supported on the first support portion 901 and the second support portion 701 respectively by bearings 10. This allows the mounting positions of both the front and rear bearings of the motor to be moved inwards, further shortening the axial length of the motor shaft 3 and reducing the overall axial length of the motor. In some embodiments, the second support portion 701 may not be provided on the front cover 7, depending on actual needs.

[0044] In the servo motor provided in the above embodiment, the first magnetic induction element 2 and the second magnetic induction element 6 are respectively disposed on two opposite surfaces of the circuit board 12, and both correspond to the magnet 11. During operation, the first magnetic induction element 2 and the second magnetic induction element 6 can simultaneously detect the magnet 11, thereby obtaining two sets of monitoring data, which helps to improve the reliability of the monitoring data. Moreover, if one encoder fails, the other encoder can still monitor, which helps to improve the stability of the motor operation. At the same time, only one magnet 11 needs to be installed on the motor shaft 3, without additionally extending the axial length of the motor shaft 3. Furthermore, the support 1 is fixed in the mounting slot and does not occupy the outer peripheral sidewall of the motor shaft 3. The installation of the encoder magnet 11 can be achieved without extending the motor shaft 3, which helps to shorten the length of the motor shaft 3 and reduce the overall axial length of the motor. The first support part 901 extends into the mounting hole 401, thereby moving the installation position of the bearing 10 inward into the motor, further shortening the axial length of the motor shaft 3.

[0045] The above examples illustrate this application only to aid understanding and are not intended to limit its scope. Those skilled in the art to which this application pertains can make various simple deductions, modifications, or substitutions based on the ideas presented.

Claims

1. A servo motor, characterized in that, include: Rotor assembly, the rotor assembly including a motor shaft; The encoder assembly includes a magnet and a circuit board. The magnet is fixed to the end face of the first end of the motor shaft by a support member. The circuit board is provided with a first magnetic induction element and a second magnetic induction element. The first magnetic induction element and the second magnetic induction element are respectively provided on two opposite sides of the circuit board and are both corresponding to the magnet, so that the first magnetic induction element and the second magnetic induction element can detect the magnet synchronously.

2. The servo motor as described in claim 1, characterized in that, The first magnetic induction element, the second magnetic induction element, and the magnet are arranged coaxially.

3. The servo motor as described in claim 1, characterized in that, The first end has an assembly groove on its end face. The magnet is fixed on the support member. The outer contour of the cross-section of the support member is circular. The cross-section is a section perpendicular to the axial direction of the motor shaft. The support member is fixed in the assembly groove to fix the magnet on the end face of the first end.

4. The servo motor as described in claim 3, characterized in that, The maximum dimension of the magnet in the direction perpendicular to the motor shaft axis is greater than or equal to the diameter of the first end. The support member is in the shape of a stepped shaft and includes a small diameter section and a large diameter section. The magnet is fixed on the end face of the large diameter section and the small diameter section is fixed in the assembly groove to fix the large diameter section and the magnet on the outside of the first end. Alternatively, the maximum dimension of the magnet in the direction perpendicular to the motor shaft axis is smaller than the diameter of the first end, the support member is cylindrical, and the cylindrical support member is fixed in the assembly groove to fix the magnet in the first end.

5. The servo motor as described in any one of claims 1-4, characterized in that, The servo motor further includes a housing and a stator. The housing includes a main body and a front cover and a rear cover respectively connected to opposite ends of the main body. The stator is disposed inside the housing and has an assembly hole. The rotor assembly is disposed in the assembly hole, and the circuit board is mounted on the rear cover. The rear cover has a first support portion protruding towards the side of the main body. At least a portion of the first support portion is located in the assembly hole, and the first end is supported on the first support portion by a bearing.

6. The servo motor as described in claim 5, characterized in that, The encoder assembly also includes a bracket, the circuit board is fixed on the bracket, the rear end cover has a receiving cavity, the bottom of the receiving cavity has a groove, the bracket is located in the groove and fixedly connected to the rear end cover to support the circuit board in the receiving cavity, and the bottom of the groove has a through hole for the magnetic induction element to sense the magnet.

7. The servo motor as described in claim 6, characterized in that, The bracket is plate-shaped and fits into the bottom of the groove. The circuit board is fixed to the side of the bracket away from the through hole. The bottom of the groove is provided with a threaded hole. Screws pass through the circuit board, and the bracket and the threaded hole cooperate to fix the circuit board, the bracket and the rear cover into one piece.

8. The servo motor as described in claim 5, characterized in that, The motor shaft includes a main body section and a mounting section. The mounting section is located at one end of the motor shaft. The diameter of the mounting section is smaller than the diameter of the main body section. The mounting section is supported on the first support part by the bearing. The axial length of the mounting section is greater than or equal to the axial length of the bearing, and the difference between the two is less than or equal to 1 mm.

9. The servo motor as described in claim 5, characterized in that, The rotor assembly includes a rotor core, which is fixed on the motor shaft. The end face of the rotor core and the wall of the mounting hole enclose a receiving space located in the mounting hole. At least a portion of the first support is located in the receiving space.

10. The servo motor as described in claim 5, characterized in that, The front end cover is provided with a second support portion protruding towards the side of the main body, and the two ends of the motor shaft are respectively supported on the first support portion and the second support portion by bearings.

Images