Motor assembling method capable of achieving self-centering through magnetic force

Abstract

The invention relates to the technical field of motors, in particular to a magnetic self-centering motor assembling method which is applied to a motor and comprises the following steps: forming a rotor assembly; a rotor assembly is rotatably and preliminarily installed on a base through a rotating shaft assembly, an end cover is preliminarily installed on the base, a bearing chamber of the end cover supports an outer ring of a bearing on the rotating shaft assembly through a radial elastic supporting unit, and the radial elastic supporting unit allows the outer ring of the bearing to slightly and radially float; a driving current is applied to the stator assembly, so that the rotor assembly generates a rotation trend or rotates at a low speed, and the rotor assembly is driven to overcome the micro radial rigidity of the radial elastic supporting unit by utilizing the unbalanced magnetic pulling force of interaction between the rotor assembly and the stator assembly; and the rotation axis of the stator assembly is automatically adjusted to a position which tends to be coaxial with the central axis of the stator assembly. The method can actively compensate radial dimension chain errors and assembly deviations accumulated in the previous process.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to a motor assembly method that utilizes magnetic self-alignment. Background Technology

[0002] In the field of motor manufacturing and assembly, ensuring precise concentricity between the rotor and stator is a core technological challenge for guaranteeing efficient, stable, and low-noise motor operation. Traditional assembly methods heavily rely on high machining precision of various components (such as the frame, end covers, and bearing housings), complex tooling fixtures, and skilled manual adjustments to ensure alignment. This method not only leads to high production costs and low production efficiency but also makes it difficult to completely eliminate misalignment problems caused by machining tolerances, accumulated assembly errors, and thermal deformation. The unilateral magnetic pull generated by misalignment can cause vibration and noise, increase additional losses, and reduce motor efficiency. More seriously, this radial force acts directly on the bearings, leading to stress concentration and abnormal wear, significantly shortening bearing life and affecting the overall reliability of the machine. Although some post-processing dynamic balancing or online self-aligning technologies exist, they are often complex in structure, expensive, or have limited applicability.

[0003] Therefore, there is a need in the field for a method that can achieve automatic and precise rotor alignment through a simple and efficient assembly process under conventional manufacturing precision, so as to fundamentally solve the above problems. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a motor assembly method utilizing magnetic self-alignment that can proactively compensate for radial dimensional chain errors and assembly deviations accumulated in previous processes. This achieves alignment results far exceeding those of traditional processes under conventional manufacturing precision, reducing production costs and reliance on operational skills.

[0005] The technical solution adopted in this invention is: a motor assembly method utilizing magnetic self-alignment, used for assembling a motor, the motor including a base, stator assembly, shaft assembly, rotor housing, rotor assembly, and end caps, the motor assembly method including the following steps: Step S1: Place the stator assembly on the base; fix the rotor assembly inside the rotor housing; and connect the shaft assembly to the rotor housing to form a rotor assembly. Step S2: The rotor assembly is initially mounted rotatably onto the base via the shaft assembly, such that the rotor assembly is located radially outside the stator assembly; Step S3: Initially install the end cap onto the base, wherein the bearing chamber of the end cap supports the outer ring of the bearing on the rotating shaft assembly through a radial elastic support unit, and the radial elastic support unit allows the outer ring of the bearing to float slightly radially; Step S4: Apply a driving current to the stator assembly to cause the rotor assembly to rotate or rotate at low speed. Utilize the unbalanced magnetic pull between the rotor assembly and the stator assembly to drive the rotor assembly to overcome the small radial stiffness of the radial elastic support unit, so that its rotation axis is automatically adjusted to a position that is close to coaxial with the central axis of the stator assembly. Step S5: While maintaining the drive current or keeping the rotor assembly in the position determined in the magnetic self-alignment step, finally fix the end cover to the base.

[0006] A further improvement to the above scheme is that, in step S4, the driving current is a pulsating DC current or a low-frequency AC current, and its magnitude is controlled to generate a rotational torque sufficient to overcome the initial static friction of the radial elastic support unit, but not sufficient to make the rotor assembly rotate continuously at high speed.

[0007] A further improvement to the above scheme is that, in step S4, the drive current is controlled to cause the rotor assembly to reciprocate for less than one revolution or to rotate continuously at a low speed, with the reciprocating or rotating time lasting from 0.5s to 5s.

[0008] A further improvement to the above scheme is that it also includes step S4.1, cutting off the drive current and detecting the rotational resistance torque of the rotor assembly or the radial runout of the shaft assembly; if the detected value exceeds a preset threshold, step S4 is repeated.

[0009] A further improvement to the above scheme is that, in step S3, grease is applied between the outer ring of the bearing and the bearing housing. The viscosity of the grease is selected to provide moderate damping during the magnetic self-alignment process in step S4, so as to help the rotor assembly quickly stabilize to the alignment position.

[0010] A further improvement to the above scheme is that, in step S4, the positional change of the rotor housing or shaft assembly relative to the base is monitored by a displacement sensor or a vision inspection system. When the monitored positional change tends to stabilize, it is determined that the self-alignment is completed, and step S5 is triggered.

[0011] A further improvement to the above scheme is that the motor is a permanent magnet brushless DC motor, the stator assembly is an armature winding, and the rotor assembly includes a permanent magnet.

[0012] A further improvement to the above scheme is that, in step S4, the drive current is output by controlling the driver connected to the armature winding.

[0013] A further improvement to the above scheme is that the radial elastic support unit includes an elastic bushing and an elastic element; the elastic bushing is sleeved on the outer ring of the bearing, and the outer wall of the elastic bushing mates with the inner wall of the bearing housing; the elastic element is disposed between the elastic bushing and the bearing housing to provide an elastic force that resets the elastic bushing. In this embodiment, at least a portion of the wall thickness of the elastic bushing is configured to undergo elastic deformation in the radial direction.

[0014] A further improvement to the above scheme is that the radial elastic support unit includes an annular groove and a flexible annular body. The annular groove is formed on the inner wall of the bearing chamber. The flexible annular body is fixedly embedded in the annular groove, and the inner annular surface of the flexible annular body protrudes from the inner wall of the bearing chamber and is directly interference-fitted or clearance-fitted with the outer ring of the bearing. The flexible ring is made of rubber, silicone, or an elastic polymer material.

[0015] The beneficial effects of this invention are: Compared to existing motor assembly methods, this invention utilizes the inherent unbalanced magnetic pull of the motor itself as the adjustment driving force. Guided by radial elastic support units, the rotor assembly automatically finds and stabilizes at the concentric position with minimal magnetic resistance. It actively compensates for radial dimensional chain errors and assembly deviations accumulated in previous processes, achieving alignment results far exceeding traditional processes under conventional manufacturing precision, thus reducing production costs and reliance on operator skills. Motors assembled using this method have a uniform air gap between the rotor and stator, eliminating unilateral magnetic pull caused by static misalignment, reducing motor vibration and noise, and improving operational stability. Simultaneously, the uniform air gap reduces asymmetrical losses in the magnetic circuit, contributing to improved motor efficiency. More importantly, the excellent alignment allows the bearings to primarily bear normal rotational loads, avoiding stress concentration and premature wear caused by abnormal radial forces, significantly extending the service life of the bearings and the entire machine, and improving product quality and reliability. This invention provides a new approach to efficient, low-cost, and high-precision motor assembly, effectively solving the alignment problems in traditional assembly methods. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the motor assembly method utilizing magnetic self-alignment according to the present invention. Figure 2 This is a three-dimensional schematic diagram of the motor of the present invention; Figure 3 for Figure 1 Internal structure diagram of embodiment 1 of the medium-sized motor; Figure 4 for Figure 3 Enlarged diagram of point A in the diagram; Figure 5 for Figure 1 Internal structure diagram of embodiment 2 of the Chinese motor; Figure 6 for Figure 5 Enlarged diagram of point A in the diagram.

[0017] Explanation of reference numerals in the attached drawings: 1. Base; 2. Stator assembly; 3. Shaft assembly; 4. Rotor housing; 5. Rotor assembly; 6. End cover; 7. Radial elastic support unit; 71. Elastic bushing; 72. Elastic element; 73. Annular groove; 74. Flexible annular body. Detailed Implementation

[0018] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0019] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Figures 1-6 As shown, in one embodiment of the present invention, a method for assembling a motor using magnetic self-alignment is provided. The motor includes a base 1, a stator assembly 2, a shaft assembly 3, a rotor housing 4, a rotor assembly 5, and an end cover 6. The motor assembly method includes the following steps: Step S1: The stator assembly 2 is placed on the base 1; the rotor assembly 5 is fixedly installed inside the rotor housing 4, and the shaft assembly 3 is connected to the rotor housing 4 to form a rotor assembly; Step S2: The rotor assembly is initially mounted rotatably onto the base 1 via the shaft assembly 3, so that the rotor assembly 5 is located radially outside the stator assembly 2; Step S3: Initially install the end cover 6 onto the base 1, wherein the bearing chamber of the end cover 6 supports the outer ring of the bearing on the rotating shaft assembly 3 through a radial elastic support unit 7, and the radial elastic support unit 7 allows the outer ring of the bearing to float slightly radially. Step S4: Apply a driving current to the stator assembly 2 to cause the rotor assembly 5 to rotate or rotate at low speed. Utilize the unbalanced magnetic pull between the rotor assembly 5 and the stator assembly 2 to drive the rotor assembly to overcome the slight radial stiffness of the radial elastic support unit 7, so that its rotation axis is automatically adjusted to a position that is close to coaxial with the central axis of the stator assembly 2. Step S5: While maintaining the drive current or keeping the rotor assembly in the position determined in the magnetic self-alignment step, the end cover 6 is finally fixedly connected to the base 1.

[0021] This embodiment utilizes the inherent unbalanced magnetic pull of the motor itself as the adjustment driving force. Guided by the radial elastic support unit 7, the rotor assembly can automatically find and stabilize at the concentric position with minimal magnetic resistance. It can actively compensate for radial dimensional chain errors and assembly deviations accumulated in previous processes, thus achieving a much higher alignment effect than traditional processes under conventional manufacturing precision, reducing production costs and reliance on operator skills. Motors assembled using this method have a uniform air gap between the rotor and stator, eliminating unilateral magnetic pull caused by static misalignment, reducing motor vibration and noise, and improving operational stability. Simultaneously, the uniform air gap also reduces asymmetrical losses in the magnetic circuit, contributing to improved motor efficiency. More importantly, the excellent alignment allows the bearings to primarily bear normal rotational loads, avoiding stress concentration and premature wear caused by abnormal radial forces, greatly extending the service life of the bearings and the entire machine, and improving product quality and reliability. This embodiment provides a new approach to efficient, low-cost, and high-precision motor assembly, effectively solving the alignment problems in traditional assembly methods.

[0022] In step S4, the driving current is a pulsating direct current or a low-frequency alternating current, the magnitude of which is controlled to generate a rotational torque sufficient to overcome the initial static friction of the radial elastic support unit 7, but insufficient to allow the rotor assembly 5 to rotate continuously at high speed. This embodiment achieves fine-tuning of the self-alignment process by using a pulsating direct current or a low-frequency alternating current as the driving current and precisely controlling its magnitude. By controlling the current to a level that only generates a rotational torque sufficient to overcome the initial static friction of the radial elastic support unit 7, but insufficient to allow the rotor to rotate continuously at high speed, it ensures that the rotor assembly can begin the necessary minute radial position adjustment under magnetic force, initiating the self-alignment process. Secondly, it avoids centrifugal force interference caused by high-speed rotor rotation, as centrifugal force may mask or counteract the alignment adjustment effect of unbalanced magnetic pull, or even lead to alignment failure.

[0023] In step S4, the drive current is controlled to cause the rotor assembly 5 to perform a reciprocating oscillation of less than one revolution or a continuous low-speed rotation, with the oscillation or rotation lasting from 0.5 s to 5 s. This embodiment limits the motion state and time of the rotor during the self-alignment process. Controlling the rotor to perform a reciprocating oscillation of less than one revolution or a continuous low-speed rotation provides the necessary process and time for the unbalanced magnetic pull to fully exert its force. The brief reciprocating oscillation or low-speed rotation allows the rotor system sufficient time to traverse its possible eccentric positions and allows the magnetic force to continuously pull the rotor towards the position of minimum magnetic resistance. Setting a time range avoids the process being too short, resulting in insufficient alignment, or too long, resulting in reduced production efficiency.

[0024] The method also includes step S4.1, which involves cutting off the drive current and detecting the rotational resistance torque of the rotor assembly 5 or the radial runout of the shaft assembly 3. If the detected value exceeds a preset threshold, step S4 is repeated. This embodiment improves the reliability and yield of the assembly method. By cutting off the current and detecting the rotational resistance torque or radial runout after magnetic alignment, the quality of the alignment result can be quantitatively evaluated. If the detected value exceeds a preset threshold, it indicates that the alignment may be insufficient or there may be other problems, and the system automatically repeats the alignment step. The closed-loop control logic ensures that each assembled motor has undergone qualification verification, preventing products with alignment defects from entering the next process or the market, and fundamentally ensuring the consistency of motor performance under mass production.

[0025] In step S3, grease is applied between the outer ring of the bearing and the bearing housing. The viscosity of the grease is selected to provide adequate damping during the magnetic self-alignment process in step S4, helping the rotor assembly to quickly stabilize to the aligned position. This embodiment optimizes the dynamic response characteristics of the self-alignment process through the targeted selection and application of grease viscosity characteristics. Applying grease of appropriate viscosity between the outer ring of the bearing and the bearing housing primarily serves to provide adequate damping when the rotor assembly moves under magnetic traction. The damping effect helps suppress overshoot or oscillation that may occur during the rotor's search for the equilibrium point, allowing the system to decay kinetic energy more quickly, smoothly approach and stabilize at the final aligned position, thereby shortening the alignment time and improving efficiency.

[0026] In step S4, the positional change of the rotor housing 4 or shaft assembly 3 relative to the base 1 is monitored by a displacement sensor or visual inspection system. When the monitored positional change tends to stabilize, self-alignment is determined to be complete, and step S5 is triggered. This embodiment achieves real-time, accurate monitoring and intelligent judgment of the self-alignment process by integrating a displacement sensor or visual inspection system. Directly monitoring the positional change of the rotor housing 4 or shaft assembly 3 can most intuitively reflect the degree of alignment. When the monitoring data indicates that the positional change tends to stabilize, that is, the rotor assembly no longer makes significant radial adjustments, the system can automatically determine that self-alignment is complete. This reduces the reliance on operator experience, improves the objectivity and accuracy of judgment, and avoids premature or delayed locking operations.

[0027] The motor is a permanent magnet brushless DC motor. The stator assembly 2 is the armature winding, and the rotor assembly 5 includes permanent magnets. This embodiment specifically applies the assembly method to a permanent magnet brushless DC motor, fully utilizing the advantages of this type of motor. The rotor assembly 5 of the permanent magnet brushless DC motor contains permanent magnets, which can generate a strong permanent magnet magnetic field and interaction force with the stator armature winding. This allows sufficient unbalanced magnetic pull for driving alignment to be generated even with a relatively small drive current, ensuring the effectiveness and efficiency of the self-alignment process.

[0028] In step S4, the drive current is output by controlling the driver connected to the armature winding. This embodiment clearly demonstrates the direct use of the motor's own driver to provide the drive current, showcasing a high degree of system integration and practicality. It eliminates the need for complex dedicated drive equipment for the assembly process, simplifying production line configuration and reducing costs. Directly controlling the existing driver to output the required pulsating or low-frequency current enables on-site control of the motor assembly process, allowing seamless integration between the assembly process and the motor's own control system.

[0029] Example 1 See Figures 3-4As shown, the radial elastic support unit 7 includes an elastic bushing 71 and an elastic element 72. The elastic bushing 71 is fitted onto the outer ring of the bearing, and the outer wall of the elastic bushing 71 mates with the inner wall of the bearing housing. The elastic element 72 is disposed between the elastic bushing 71 and the bearing housing to provide an elastic force that allows the elastic bushing 71 to return to its original position. At least a portion of the wall thickness of the elastic bushing 71 is configured to allow for radial elastic deformation. This embodiment features a split structure for the elastic bushing 71 and the elastic element 72. The elastic bushing 71 is directly fitted onto the outer ring of the bearing, serving as the main body that bears radial force and deforms. Its specific deformable wall thickness design ensures the compliance required for radial floating. The independent elastic element 72 (such as a wave spring) specifically provides a reliable restoring elastic force, ensuring that the system can maintain or return to a stable state after the centering force disappears or changes. Each part can be independently optimized in terms of materials and structure (such as wear-resistant bushings and anti-relaxation elastic element 72), making it easy to manufacture and assemble. More importantly, by replacing elastic elements 72 of different specifications, the radial stiffness and preload of the system can be flexibly adjusted, so that the same basic structure can be adapted to the specific requirements of different models and power motors for floating amount and self-aligning force, with excellent versatility and adjustability.

[0030] Example 2 See Figures 5-6 As shown, the radial elastic support unit 7 includes an annular groove 73 and a flexible annular body 74. The annular groove 73 is formed on the inner wall of the bearing chamber. The flexible annular body 74 is fixedly embedded in the annular groove 73, and the inner annular surface of the flexible annular body 74 protrudes from the inner wall of the bearing chamber and directly interferes with or clearance-fits with the outer ring of the bearing. The flexible annular body 74 is made of rubber, silicone, or an elastic polymer material. This embodiment provides another effective implementation of the radial elastic support unit 7. This method has a simple structure, consisting of an annular groove 73 and an embedded flexible annular body 74 (such as a rubber ring). It has fewer parts, simplifies the assembly process, and significantly reduces manufacturing costs and improves assembly efficiency. The flexible annular body 74 material (such as rubber or silicone) not only provides the required radial elastic deformation to achieve slight floating of the bearing outer ring, but its inherent high internal resistance also provides excellent damping and vibration reduction effects.

[0031] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A method for assembling a motor using magnetic self-alignment, for assembling a motor, the motor comprising a base, a stator assembly, a shaft assembly, a rotor housing, a rotor assembly, and end covers, characterized in that: The motor assembly method includes the following steps: Step S1: Place the stator assembly on the base; fix the rotor assembly inside the rotor housing; and connect the shaft assembly to the rotor housing to form a rotor assembly. Step S2: The rotor assembly is initially mounted rotatably onto the base via the shaft assembly, such that the rotor assembly is located radially outside the stator assembly; Step S3: Initially install the end cap onto the base, wherein the bearing chamber of the end cap supports the outer ring of the bearing on the rotating shaft assembly through a radial elastic support unit, and the radial elastic support unit allows the outer ring of the bearing to float slightly radially; Step S4: Apply a driving current to the stator assembly to cause the rotor assembly to rotate or rotate at low speed. Utilize the unbalanced magnetic pull between the rotor assembly and the stator assembly to drive the rotor assembly to overcome the small radial stiffness of the radial elastic support unit, so that its rotation axis is automatically adjusted to a position that is close to coaxial with the central axis of the stator assembly. Step S5: While maintaining the drive current or keeping the rotor assembly in the position determined in the magnetic self-alignment step, finally fix the end cover to the base.

2. The motor assembly method utilizing magnetic self-alignment according to claim 1, characterized in that: In step S4, the driving current is a pulsating direct current or a low-frequency alternating current, and its magnitude is controlled to generate a rotational torque sufficient to overcome the initial static friction of the radial elastic support unit, but insufficient to make the rotor assembly rotate continuously at high speed.

3. The motor assembly method utilizing magnetic self-alignment according to claim 2, characterized in that: In step S4, the drive current is controlled to make the rotor assembly reciprocate for less than one revolution or rotate continuously at a low speed for 0.5s to 5s.

4. The motor assembly method utilizing magnetic self-alignment according to claim 1, characterized in that: It also includes step S4.1, cutting off the drive current and detecting the rotational resistance torque of the rotor assembly or the radial runout of the shaft assembly; if the detected value exceeds a preset threshold, step S4 is repeated.

5. The motor assembly method utilizing magnetic self-alignment according to claim 1, characterized in that: In step S3, grease is applied between the outer ring of the bearing and the bearing housing. The viscosity of the grease is selected such that it can provide adequate damping during the magnetic self-alignment process in step S4 to help the rotor assembly quickly stabilize to the alignment position.

6. The motor assembly method utilizing magnetic self-alignment according to claim 5, characterized in that: In step S4, the positional change of the rotor housing or shaft assembly relative to the base is monitored by a displacement sensor or a vision inspection system. When the monitored positional change tends to stabilize, it is determined that the self-alignment is completed and step S5 is triggered.

7. The motor assembly method utilizing magnetic self-alignment according to claim 1, characterized in that: The motor is a permanent magnet brushless DC motor, the stator assembly is an armature winding, and the rotor assembly includes permanent magnets.

8. The motor assembly method utilizing magnetic self-alignment according to claim 7, characterized in that: In step S4, the drive current is output by controlling the driver connected to the armature winding.

9. The motor assembly method utilizing magnetic self-alignment according to claim 1, characterized in that: The radial elastic support unit includes an elastic bushing and an elastic element; the elastic bushing is sleeved on the outer ring of the bearing, and the outer wall of the elastic bushing mates with the inner wall of the bearing housing; the elastic element is disposed between the elastic bushing and the bearing housing to provide an elastic force that resets the elastic bushing. In this embodiment, at least a portion of the wall thickness of the elastic bushing is configured to undergo elastic deformation in the radial direction.

10. The motor assembly method utilizing magnetic self-alignment according to claim 1, characterized in that: The radial elastic support unit includes an annular groove and a flexible ring body. The annular groove is formed on the inner wall of the bearing chamber. The flexible ring body is fixedly embedded in the annular groove. The inner ring surface of the flexible ring body protrudes from the inner wall of the bearing chamber and is directly interference-fitted or clearance-fitted with the outer ring of the bearing. The flexible ring is made of rubber, silicone, or an elastic polymer material.

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