electric machine

Abstract

This invention relates to the field of motor technology, specifically to a motor comprising: a housing, within which a stator assembly and a rotor assembly are disposed; an output shaft assembly passing through the center of the rotor core; the output shaft assembly and the rotor core are fixed together by injection molding of an insulating component, and a parasitic capacitance exists between the rotor core and the output shaft assembly; a pair of end caps, respectively disposed at both ends of the housing; bearings are disposed on the end caps, and the two ends of the output shaft assembly pass through and are connected to the corresponding bearings; and a conductive component disposed between the output shaft assembly and the rotor core; the conductive component is used to adjust the parasitic capacitance. This solution utilizes a dedicated conductive component between the rotor core and the output shaft assembly to directly regulate the parasitic capacitance, thereby reducing the potential difference between the inner and outer rings of the bearing, lowering the shaft voltage, and thus preventing excessive shaft voltage from causing electrical corrosion of the motor bearings, ensuring the motor's service life and operational stability.

Description

Technical Field

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

[0002] To improve the magnetization effect, existing motors generally adopt a rotor block structure design. This structure will result in a smaller parasitic capacitance value between the rotor core and the motor shaft, which will cause an imbalance in the voltage distribution of the parasitic capacitance network inside the motor. In addition, some motors will have a situation where the potential to ground on the end cover side is much higher than the potential on the shaft side, that is, the potential of the outer ring of the bearing is higher than the potential of the inner ring of the bearing, thus forming an excessively high shaft voltage.

[0003] However, excessively high shaft voltage can cause electrical corrosion of motor bearings, seriously affecting the service life and operational stability of the motor. Summary of the Invention

[0004] In view of this, the present invention provides an electric motor to solve the problem of excessively high shaft voltage caused by the bearing outer ring potential being higher than the bearing inner ring potential.

[0005] In a first aspect, the present invention provides an electric motor comprising: The housing contains a stator assembly and a rotor assembly; the stator assembly includes stator windings, and the rotor assembly includes a rotor core. The output shaft assembly passes through the center of the rotor core; the output shaft assembly and the rotor core are fixed together by injection molding of an insulating component, and there is parasitic capacitance between the rotor core and the output shaft assembly; A pair of end caps are respectively located at both ends of the housing; bearings are installed on the end caps, and the two ends of the output shaft assembly pass through and are connected to the corresponding bearings; A conductive element is disposed between the output shaft assembly and the rotor core; the conductive element is used to adjust the parasitic capacitance.

[0006] Beneficial effects: The parasitic capacitance formed between the rotor core and the output shaft assembly is too small, which is the root cause of excessively high motor shaft voltage. Therefore, this technical solution sets up a conductive component between the rotor core and the output shaft assembly, which can directly regulate the parasitic capacitance. This changes the voltage division ratio of the Wheatstone bridge network of parasitic capacitance inside the motor, reduces the potential difference between the inner and outer rings of the bearing, and lowers the shaft voltage. This prevents excessively high shaft voltage from causing electrical corrosion of the motor bearings, ensuring the service life and operational stability of the motor.

[0007] Meanwhile, in this solution, since the conductive components are only located between the rotor core and the output shaft assembly, the core structure of the motor, such as the stator winding, rotor core, and housing, is not altered. There is no need to replace the existing production molds, and the original electromagnetic parameters of the motor will not be affected.

[0008] In one alternative implementation, when the output shaft assembly includes only the output shaft, the conductive element is a conductive sheet, and the conductive sheet is in contact with the rotor core.

[0009] Beneficial effects: This implementation method is designed for motors without existing bushings. Therefore, a conductive sheet can be selected as the conductive component. The contact engagement between the conductive sheet and the rotor core directly enables conduction between the rotor core and the output shaft, maximizing the parasitic capacitance between them and rapidly changing the voltage division ratio of the bridge network, thus achieving a rapid improvement in shaft voltage. Furthermore, the contact engagement assembly method eliminates the need for precise control of gap dimensions, reducing production and assembly difficulty and making it suitable for mass production. In addition, the conductive sheet is small in size, simple in structure, does not occupy additional internal space in the motor, and does not alter the overall structural layout of the motor.

[0010] In one alternative implementation, when the output shaft assembly includes only the output shaft, the conductive element is an additional bushing, and the additional bushing and the rotor core are in a clearance fit or a contact fit.

[0011] Beneficial Effects: This embodiment, also targeting motors without existing bushings, innovatively uses an additional bushing as a conductive component. Compared to conductive sheets, the additional bushing has a larger mating area with the rotor core and output shaft, resulting in a wider and more precise adjustment range for parasitic capacitance. Furthermore, when using a clearance fit, the target value of parasitic capacitance can be precisely matched by adjusting the clearance size, thereby reducing the potential difference between the inner and outer rings of the bearing, lowering the shaft voltage, and bringing it to its optimal value. When using a contact fit, the parasitic capacitance can be rapidly increased, achieving a rapid improvement in shaft voltage. Both fit methods can be flexibly selected based on the actual shaft voltage detection of the motor, adapting to motors of different specifications. Similarly, in this embodiment, the additional bushing is only fitted onto the output shaft, without altering other core components of the motor, thus ensuring that the original electromagnetic parameters remain unaffected.

[0012] In one alternative implementation, the outer surface of the additional bushing has a circular or polygonal structure.

[0013] Beneficial effects: In this embodiment, since a circular structure is a conventional structure for motor shaft accessories, the additional bushing with a circular structure can be perfectly fitted to the circular mounting space inside the motor, resulting in smooth and seamless assembly. If a polygonal structure is used, the contact area with the rotor core can be increased, further improving the adjustment effect on parasitic capacitance. Simultaneously, the polygonal structure can also provide circumferential positioning, preventing relative rotation between the additional bushing and the output shaft and rotor core, avoiding fluctuations in capacitance adjustment caused by rotation, and thus improving the stability of motor operation.

[0014] In one alternative implementation, the additional bushing includes: The bushing body has a circular structure. Multiple connecting parts are evenly arranged on the outer circumference of the bushing body; the connecting parts are arranged corresponding to each toothed yoke on the rotor core.

[0015] Beneficial effects: In this embodiment, the circular bushing body ensures smooth assembly between the bushing body and the output shaft, avoiding jamming between the bushing and the output shaft. Furthermore, the circumferentially uniform connecting parts correspond one-to-one with the rotor core tooth yoke, allowing for a closer fit and more even force distribution between the additional bushing and the rotor core, preventing poor parasitic capacitance adjustment caused by localized poor contact. Simultaneously, the corresponding arrangement of the connecting parts and the tooth yoke precisely matches the original structure of the rotor core, without altering the tooth yoke layout, ensuring the rotor core's magnetic focusing effect remains unaffected, thus maintaining the motor's original power performance. Furthermore, the evenly distributed connecting parts result in a more uniform distribution of parasitic capacitance between the bushing and the rotor core, preventing localized bearing corrosion caused by excessive localized potential differences, and improving the overall operational reliability of the motor.

[0016] In one alternative embodiment, the connecting portion has a groove on the side near the rotor core, the groove being adapted to accommodate the toothed yoke.

[0017] Beneficial effects: In this embodiment, the groove portion forms a covering and positioning system for the rotor core's toothed yoke portion, which further improves the fit between the additional bushing and the rotor core, preventing radial or circumferential relative displacement between the bushing and the rotor core during high-speed motor operation. This ensures the long-term stability of the parasitic capacitance adjustment effect, preventing fluctuations due to component displacement. Simultaneously, the groove portion's accommodating structure further increases the contact area between the bushing and the rotor core, thereby optimizing the parasitic capacitance adjustment effect and making the shaft voltage more stable. Furthermore, the groove portion's structural design perfectly matches the rotor core's toothed yoke portion, requiring no processing modifications to the rotor core and preserving its original structure and performance.

[0018] In one optional embodiment, the bushing body has multiple weight-reducing holes, which are evenly distributed along the circumference of the bushing body and do not penetrate through the axial ends of the bushing body.

[0019] Beneficial effects: This embodiment features a lightweight perforated design for the bushing body. The evenly distributed circumferential holes reduce the amount of material used in the bushing while ensuring uniform circumferential stress on the bushing body. This avoids a decrease in structural strength due to localized perforations and does not affect the bushing's conductivity or the stability of its fit with the output shaft and rotor core. Furthermore, the perforation design does not alter the bushing's core conductive but non-magnetic properties, nor does it change the fit between the bushing and the rotor core. It does not affect the adjustment effect of parasitic capacitance and ensures that the original electromagnetic parameters of the motor remain unchanged.

[0020] In one alternative embodiment, when the output shaft assembly includes an output shaft and an existing bushing mounted on the output shaft, the conductive element is a conductive sheet, and the conductive sheet is in contact with the rotor core.

[0021] Beneficial Effects: This implementation method is designed for motors with existing bushings. Adding an extra bushing would lead to redundancy in the motor's internal structure, occupying too much space and even affecting the assembly of other components. Therefore, a conductive sheet is chosen as the conductive component. It is small in size, easy to install, and can be directly placed between the existing bushing and the rotor core without disassembling the existing bushing or changing the original assembly structure of the motor's bushing. Furthermore, because the conductive sheet contacts and engages with the rotor core, it effectively conducts electricity between the existing bushing, the output shaft, and the rotor core, adjusting the parasitic capacitance between the three and changing the voltage division ratio of the bridge network to reduce the shaft voltage. At the same time, the installation process of the conductive sheet is simple, does not modify other core components of the motor, and does not require significant modifications to the motor, thus ensuring that the original electromagnetic parameters remain unaffected.

[0022] In one alternative embodiment, the conductive element is made of a conductive and non-magnetic material.

[0023] Beneficial effects: The conductivity of the conductive components is fundamental to achieving the connection between the rotor core and the output shaft assembly and adjusting parasitic capacitance. Ensuring the conductive components effectively change the parasitic capacitance value between them, thereby altering the voltage division of the bridge network and improving shaft voltage. Furthermore, in this embodiment, the non-magnetic property prevents the conductive components from interfering with the magnetic field distribution inside the motor, ensuring normal magnetic coupling between the stator windings and the rotor core, and preserving the original electromagnetic parameters of the motor.

[0024] In one alternative embodiment, the conductive element is made of at least one of aluminum, copper, or stainless steel.

[0025] Beneficial effects: Aluminum and copper are highly conductive but non-magnetic materials with excellent conductivity, enabling rapid and stable conduction between the rotor core and output shaft assembly. This allows for efficient and stable adjustment of parasitic capacitance, ensuring the reliability of shaft voltage improvement. Furthermore, aluminum and copper are lightweight, preventing an increase in the overall weight of the motor and avoiding increased load on the motor bearings due to added weight. Meanwhile, stainless steel, in addition to its core properties of being conductive but non-magnetic, also possesses excellent corrosion and wear resistance, allowing it to adapt to the enclosed, dusty, and slightly humid working environment inside the motor. This significantly extends the service life of conductive components, thereby ensuring the long-term stability of the motor's shaft voltage adjustment effect. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the specific embodiments or related technologies of the present invention, the drawings used in the description of the specific embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the ungrounded bridge equivalent circuit in an embodiment of the present invention; Figure 2 for Figure 1 A schematic diagram showing that the front and rear covers are not electrically connected; Figure 3 This is a schematic diagram of the structure of the additional bushing in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of the connecting part with the additional bushing in an embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures: 1. Additional bushing; 11. Bushing body; 12. Connecting part; 121. Groove part; 2. Rotor core; 21. Tooth yoke. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used for the convenience of describing the invention and for simplification, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes and should not be construed as indicating or implying relative importance.

[0031] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] To improve the magnetization effect, existing motors generally adopt a rotor block structure design. This structure leads to a smaller parasitic capacitance value between the rotor core 2 and the motor shaft, which in turn causes an imbalance in the voltage distribution of the parasitic capacitance network inside the motor. In some motors, the potential to ground on the end cover side is much higher than the potential on the shaft side, that is, the potential of the outer ring of the bearing is higher than the potential of the inner ring of the bearing, resulting in excessively high shaft voltage. Ultimately, this leads to electrical corrosion of the motor bearings, which seriously affects the service life and operational stability of the motor.

[0034] To address the problem of excessive shaft voltage, existing technologies typically optimize parasitic capacitance distribution by adjusting the motor's electromagnetic or structural design. However, this approach has significant drawbacks in practical applications. First, once the parameters of the motor body are determined, the related design adjustments are difficult and can easily increase the motor manufacturing cost. Secondly, with relatively fixed production molds, it is difficult to effectively adjust the shaft voltage while ensuring that the original core parameters of the motor remain unchanged, making it impossible to meet the dual requirements of motor performance stability and shaft voltage improvement.

[0035] Therefore, there is an urgent need in this field for a low-cost, easy-to-implement motor that does not change or only slightly alters the external electromagnetic parameters of the motor.

[0036] The following is combined with Figures 1 to 4 The following describes embodiments of the present invention.

[0037] According to an embodiment of the present invention, in one aspect, an electric motor is provided, the electric motor including a housing, an output shaft assembly, an end cap, and conductive elements.

[0038] Specifically, in this embodiment, a stator assembly and a rotor assembly are disposed within the housing. The stator assembly includes stator windings and a stator core, and the rotor assembly includes a rotor core 2 and magnets mounted on the rotor core 2. The inner diameter of the housing is adapted to the outer diameter of the stator core, and the inner wall of the housing may be provided with positioning grooves to achieve circumferential positioning of the stator core and prevent relative rotation between the stator core and the housing during motor operation. Furthermore, flange edges may be provided at both ends of the housing, and evenly distributed mounting holes may be provided on the flange edges for fixed connection with end covers.

[0039] Furthermore, in this embodiment, the output shaft assembly passes through the center of the rotor core, and there is a gap between the output shaft assembly and the rotor core. Plastic is placed in this gap, and the output shaft assembly and rotor core are then fixed together by injection molding. Thus, the physical connection between the rotor core and the shaft is achieved through injection molding. The plastic can be an insulating component.

[0040] Furthermore, there is parasitic capacitance between the rotor core 2 and the output shaft assembly. The output shaft assembly may consist only of the output shaft, or it may consist of the output shaft and an existing bushing mounted on the output shaft.

[0041] Furthermore, in this embodiment, a pair of end caps are respectively disposed at both ends of the housing; bearings are disposed on the end caps, and the two ends of the output shaft assembly pass through and are connected to the corresponding bearings. It should be noted that, in this embodiment, the bearing includes an inner bearing ring and an outer bearing ring. The inner bearing ring is installed and connected to the bearing mating section of the output shaft, and the outer bearing ring is installed and connected to the bearing housing of the end cap. The two ends of the output shaft pass through the bearings of the front end cap and the rear end cap respectively and form a rotational fit with the bearings, ensuring the high-speed and stable rotation of the output shaft.

[0042] Furthermore, in this embodiment, a conductive element is disposed between the output shaft assembly and the rotor core 2, and the conductive element is used to adjust the parasitic capacitance.

[0043] For the method of fixing the conductive component, the conductive component can be installed between the output shaft assembly and the rotor core 2, and then the conductive component, the output shaft assembly and the rotor core 2 can be fixed together by injection molding.

[0044] Because there is a gap between rotor core 2 and the output shaft assembly, according to the capacitance formula: C = ε*S / D, where ε is the dielectric constant, S is the area between the capacitor plates, and D is the distance between the plates. Therefore, the value of the parasitic capacitance can be adjusted by adjusting the gap between the rotor core 2 and the output shaft assembly.

[0045] The specific calculation method in this embodiment is as follows: like Figure 1As shown, in the ungrounded bridge equivalent circuit, due to the capacitance distribution on the shaft side, the common-mode voltage is divided to the potential of the inner ring of the bearing, i.e., the shaft side potential. And, due to the capacitance distribution on the end cap side, the common-mode voltage is divided to the potential of the outer ring of the bearing, i.e., the end cap side potential. Therefore, the potential difference Vsh between the inner and outer rings of the bearing is the shaft voltage.

[0046] like Figure 2 As shown, in the ungrounded bridge equivalent circuit, since the front and rear covers are not conductive, the front and rear covers form a capacitor bridge equivalent circuit with the inner ring of the bearing respectively. The shaft voltages Vsh1 and Vsh2 of the front and rear bearings need to be tested separately. Both shaft voltages need to be within the qualified range to ensure that the bearing will not experience electro-corrosion.

[0047] Furthermore, such as Figure 1 The diagram shows the equivalent circuit of a parasitic Wheatstone bridge. In this equivalent circuit, it is assumed that the equivalent capacitance of bridge arm 1 is C1, the equivalent capacitance of bridge arm 2 is C2, the equivalent capacitance of bridge arm 3 is C3, and the equivalent capacitance of bridge arm 4 is C4. Figure 2 As shown, when the front and rear covers are not conductive, the equivalent capacitances of bridge arm 1 are C11 and C12, and the equivalent capacitances of bridge arm 3 are C31 and C32.

[0048] The distance D between the outer surface of the bushing and the rotor core 2 is designed to achieve the optimal shaft voltage, and can be based on the following formula: In other words, the shaft voltage is lowest when C1 / C3 = C2 / C4.

[0049] Furthermore, the capacitance of bridge arm 2 is decomposed into the equivalent capacitance C21 without an insulated rotor, and the capacitance C22 between the rotor core 2 and the output shaft. However, when it is an insulated rotor, C22 = Cd; Cd is the equivalent capacitance of the insulated rotor. When C1 / C3≥C21 / C4, since C21 remains basically unchanged due to the fixed structure of the motor, the value of C2 is determined by C22 according to the principle of series capacitor, and the larger C22 is, the better. Therefore, the smaller the gap between the rotor core 2 and the output shaft assembly, the better.

[0050] When C1 / C3≤C2 / C4, and C2 is the series capacitance of C21 and Cd, in order to obtain a smaller shaft voltage value, it is not necessary to use a shaft sleeve. If necessary, the distance between the rotor core 2 and the shaft needs to be further increased.

[0051] When (C21 / / Cd) / C4 < C1 / C3 < C21 / C4, there exists a value such that C1 / C3 = C2 / C4; At this point, C2 = C1 / C3*C4, and C22 = C2*C21 / (C21-C2). Based on the capacitance formula, we can then calculate: D=ε*S / C22=ε*S*(C21-C2) / (C2*C21); That is, D=ε*S*(C21-C1 / C3*C4) / (C1 / C3*C4*C21).

[0052] Therefore, it can be seen that the excessively small parasitic capacitance between the rotor core 2 and the output shaft assembly is the root cause of the excessively high motor shaft voltage. Therefore, this technical solution sets up a conductive component between the rotor core 2 and the output shaft assembly, which can directly regulate the parasitic capacitance. This changes the voltage division ratio of the Wheatstone bridge network of the parasitic capacitance inside the motor, reduces the potential difference between the inner and outer rings of the bearing, and lowers the shaft voltage. This can prevent excessively high shaft voltage from causing electrical corrosion of the motor bearings, and ensure the service life and operational stability of the motor.

[0053] Meanwhile, in this solution, since the conductive components are only located between the rotor core 2 and the output shaft assembly, the core structure of the motor, such as the stator winding, rotor core 2, and housing, is not altered. There is no need to replace the existing production molds, and the original electromagnetic parameters of the motor will not be affected.

[0054] Furthermore, in an optional embodiment, when the output shaft assembly includes only the output shaft, the conductive element is a conductive sheet, and the conductive sheet is in contact with the rotor core 2.

[0055] In this embodiment, the conductive sheet can be a ring-shaped thin sheet structure. The outer diameter of the conductive sheet can be adapted to the inner diameter of the rotor core 2, and the inner diameter of the conductive sheet can be adapted to the outer diameter of the original bushing. Since the conductive sheet is thin, it does not occupy additional internal space of the motor and does not change the overall structural layout of the motor.

[0056] Of course, multiple contact bosses can also be provided on the outer peripheral surface of the conductive sheet. The contact bosses are evenly distributed along the circumference of the conductive sheet, and the size of the contact bosses is adapted to the toothed yoke 21 of the rotor core 2. The contact bosses are in close contact with the toothed yoke 21 of the rotor core 2 to ensure a reliable electrical connection between the conductive sheet and the rotor core 2, and to avoid poor parasitic capacitance adjustment due to poor contact.

[0057] This implementation is designed for motors without existing bushings. Therefore, a conductive sheet can be selected as the conductive component. The conductive sheet contacts the rotor core 2, directly establishing conductivity between the rotor core 2 and the output shaft. This maximizes the parasitic capacitance between them, rapidly changing the voltage division ratio of the bridge network and achieving a quick improvement in shaft voltage. Furthermore, the contact assembly method eliminates the need for precise control of gap dimensions, reducing production and assembly difficulty and making it suitable for mass production. Additionally, the conductive sheet is small in size, simple in structure, does not occupy additional internal space in the motor, and does not alter the overall structural layout of the motor.

[0058] Furthermore, in an alternative embodiment, when the output shaft assembly includes only the output shaft, the conductive element is an additional bushing 1, and the additional bushing 1 and the rotor core 2 are in a clearance fit or a contact fit.

[0059] Specifically, in this embodiment, if the original bushing is not installed on the output shaft when the motor leaves the factory, the additional bushing 1 can be installed in the gap between the output shaft and the rotor core 2. The additional bushing 1 can be interference-fitted with the output shaft, and the additional bushing 1 and the rotor core 2 can be clearance-fitted. Thus, the gap value between the additional bushing 1 and the rotor core 2 can be adjusted according to the actual shaft voltage detection.

[0060] This embodiment also addresses motor scenarios without the original bushing. It innovatively employs an additional bushing 1 as a conductive component. Compared to a conductive sheet, the additional bushing 1 has a larger mating area with the rotor core 2 and the output shaft, resulting in a wider adjustment range and higher precision for parasitic capacitance. Furthermore, when using a clearance fit, the target value of the parasitic capacitance can be precisely matched by adjusting the clearance size, thereby reducing the potential difference between the inner and outer rings of the bearing, lowering the shaft voltage, and bringing the shaft voltage to its optimal value. When using a contact fit, the parasitic capacitance can be rapidly increased, achieving a rapid improvement in shaft voltage. The two fit methods can be flexibly selected based on the actual shaft voltage detection of the motor, adapting to motors of different specifications. Similarly, in this embodiment, the additional bushing 1 is only fitted onto the output shaft without altering other core components of the motor, thus ensuring that the original electromagnetic parameters remain unaffected.

[0061] Furthermore, in an alternative embodiment, the outer surface of the additional bushing 1 has a circular or polygonal structure.

[0062] In this embodiment, since a circular structure is a conventional structure for motor shaft accessories, therefore... Figure 3 As shown, the circular additional bushing 1 can be perfectly fitted to the circular mounting space inside the motor, ensuring smooth and seamless assembly. If a polygonal structure is used, the contact area with the rotor core 2 can be increased, further improving the adjustment effect on parasitic capacitance. Simultaneously, the polygonal structure provides circumferential positioning, preventing relative rotation between the additional bushing 1 and the output shaft and rotor core 2, avoiding fluctuations in capacitance adjustment caused by rotation, and thus improving the stability of motor operation.

[0063] Furthermore, in an alternative implementation, such as Figure 4 As shown, the additional bushing 1 includes a bushing body 11 and a plurality of connecting parts 12.

[0064] Specifically, in this embodiment, the bushing body 11 has a circular structure, and the inner diameter of the bushing body 11 is adapted to the diameter of the output shaft. A plurality of connecting parts 12 are evenly arranged on the outer circumference of the bushing body 11, and the connecting parts 12 are correspondingly arranged with each toothed yoke 21 on the rotor core 2.

[0065] Regarding the connection method between the connecting part 12 and the bushing body 11, the connecting part 12 and the bushing body 11 can be an integrally formed structure, which can be manufactured by CNC turning and milling. Of course, the connecting part 12 and the bushing body 11 can also be a separate structure, and the connecting part 12 and the bushing body 11 can be connected by welding, snap-fitting, riveting, or other methods.

[0066] Of course, this embodiment is merely an example of the connection method between the connecting part 12 and the bushing body 11, but it does not limit the scope of the embodiment. Those skilled in the art can make changes according to the actual situation, as long as the same technical effect can be achieved.

[0067] In this embodiment, the circular bushing body 11 ensures smooth assembly between the bushing body 11 and the output shaft, preventing jamming between the bushing and the output shaft. Furthermore, the circumferentially uniform connecting portions 12 correspond one-to-one with the toothed yoke portions 21 of the rotor core 2, allowing for a closer fit and more even force distribution between the additional bushing 1 and the rotor core 2, avoiding poor parasitic capacitance adjustment caused by localized poor contact. Simultaneously, the corresponding arrangement of the connecting portions 12 and the toothed yoke portions 21 precisely matches the original structure of the rotor core 2, without altering the toothed yoke layout, ensuring that the magnetic focusing effect of the rotor core 2 remains unaffected, thereby maintaining the original power performance of the motor. Furthermore, the evenly distributed connecting portions 12 make the parasitic capacitance distribution between the bushing and the rotor core 2 more uniform, preventing localized electrolytic corrosion of the bearings caused by excessive localized potential differences, and improving the overall operational reliability of the motor.

[0068] Furthermore, in an alternative implementation, such as Figure 4 As shown, the connecting part 12 has a groove 121 on the side near the rotor core 2, and the groove 121 is adapted to accommodate the toothed yoke 21.

[0069] Specifically, the groove 121 can be configured as a U-shaped groove, giving it a certain depth and width, thus adapting the groove 121 to the dimensions of the yoke 21 of the rotor core 2 and accommodating it. The inner wall surface of the groove 121 can fit snugly against the yoke 21. The two ends of the groove 121 are chamfered and converge inward to prevent sharp corners from scratching the rotor core 2, while also facilitating the assembly of the additional bushing 1 with the rotor core 2.

[0070] In this embodiment, the groove 121 encloses and positions the toothed yoke 21 of the rotor core 2, further improving the fit between the additional bushing 1 and the rotor core 2. This prevents radial or circumferential relative displacement between the bushing and the rotor core 2 during high-speed motor operation, ensuring long-term stability of the parasitic capacitance adjustment effect without fluctuations due to component displacement. Simultaneously, the accommodating structure of the groove 121 further increases the contact area between the bushing and the rotor core 2, thereby optimizing the parasitic capacitance adjustment effect and making the shaft voltage more stable. Furthermore, the structural design of the groove 121 perfectly matches the toothed yoke 21 of the rotor core 2, requiring no processing modifications to the rotor core 2 and preserving its original structure and performance.

[0071] Furthermore, in an optional embodiment, the bushing body 11 is provided with a plurality of weight-reducing holes, which are evenly distributed along the circumference of the bushing body 11 and do not penetrate through the axial ends of the bushing body 11.

[0072] This embodiment features a lightweight perforated design for the bushing body 11. The evenly distributed circumferential holes reduce the material used in the bushing while ensuring uniform circumferential stress on the bushing body 11. This avoids a decrease in structural strength due to localized perforations and does not affect the bushing's conductivity or the stability of its fit with the output shaft and rotor core 2. Furthermore, the perforation design does not alter the bushing's conductive but non-magnetic core properties, nor does it change the fit between the bushing and the rotor core 2. It does not affect the adjustment effect of parasitic capacitance and ensures that the original electromagnetic parameters of the motor remain unchanged.

[0073] Furthermore, in an optional embodiment, when the output shaft assembly includes an output shaft and an existing bushing mounted on the output shaft, the conductive element is a conductive sheet, and the conductive sheet is in contact with the rotor core 2.

[0074] Specifically, in this embodiment, if the output shaft is equipped with an original bushing when the motor leaves the factory, the conductive sheet can be placed in the gap between the output shaft and the rotor core 2, and the conductive sheet and the rotor core 2 are in contact and fit together.

[0075] This implementation is designed for motors with existing bushings. Adding an extra bushing 1 would lead to redundancy in the motor's internal structure, occupying too much space and potentially affecting the assembly of other components. Therefore, a conductive sheet is chosen as the conductive component. It is small, easy to install, and can be directly placed between the existing bushing and the rotor core 2 without disassembling the existing bushing or altering its assembly structure. Furthermore, because the conductive sheet contacts and engages with the rotor core 2, it effectively conducts electricity between the existing bushing, the output shaft, and the rotor core 2, adjusting the parasitic capacitance between them, changing the voltage division ratio of the bridge network, and reducing the shaft voltage. Simultaneously, the installation process for the conductive sheet is simple, does not alter other core components of the motor, and requires no major modifications to the motor, thus ensuring that the original electromagnetic parameters remain unaffected.

[0076] Furthermore, in an alternative embodiment, the conductive element is made of a conductive and non-magnetic material.

[0077] Since the conductivity of the conductive component is fundamental to achieving the connection between the rotor core 2 and the output shaft assembly and adjusting parasitic capacitance, ensuring that the conductive component can effectively change the parasitic capacitance value between them, thereby changing the voltage division of the bridge network and improving the shaft voltage. Furthermore, in this embodiment, the non-magnetic property can prevent the conductive component from interfering with the magnetic field distribution inside the motor, ensuring normal magnetic coupling between the stator winding and the rotor core 2, and not changing the original electromagnetic parameters of the motor.

[0078] Furthermore, in one alternative embodiment, the conductive element is made of at least one of aluminum, copper, or stainless steel.

[0079] Because aluminum and copper are highly conductive but non-magnetic materials, they possess excellent conductivity, enabling rapid and stable conduction between the rotor core 2 and the output shaft assembly. This allows for efficient and stable adjustment of parasitic capacitance, ensuring the reliability of the shaft voltage improvement effect. Furthermore, aluminum and copper are lightweight, preventing an increase in the overall weight of the motor and avoiding increased load on the motor bearings due to added weight. Meanwhile, stainless steel, in addition to its core properties of being conductive but non-magnetic, also exhibits excellent corrosion and wear resistance, allowing it to adapt to the enclosed, dusty, and slightly humid working environment inside the motor. This significantly extends the service life of conductive components, thereby ensuring the long-term stability of the motor's shaft voltage adjustment effect.

[0080] The test results are as follows: In air conditioner BLDC plastic-encapsulated motors, when the motor uses a modular rotor structure and does not use the original bushing, an additional bushing 1 or a metal conductive sheet can be used to adjust the motor's parasitic capacitance, thereby reducing the shaft voltage and keeping it within the acceptable range, thus reducing the risk of bearing failure. Before the improvement, the shaft voltage was between 5 and 8V; after the improvement, the shaft voltage is between 3 and 5V.

[0081] In air conditioner BLDC (Blended Black-Chip) motors with modular rotor structures and existing bushings, metal conductive sheets can be used to adjust the motor's parasitic capacitance, thereby reducing the shaft voltage and keeping it within acceptable limits, thus lowering the risk of bearing failure. Before the improvement, the shaft voltage was between 5 and 8V; after the improvement, the shaft voltage is between 3 and 5V.

[0082] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. An electric motor, characterized in that, include: The housing contains a stator assembly and a rotor assembly; the stator assembly includes stator windings, and the rotor assembly includes a rotor core (2). The output shaft assembly passes through the center of the rotor core (2); the output shaft assembly and the rotor core (2) are fixed together by injection molding of an insulating component, and there is a parasitic capacitance between the rotor core (2) and the output shaft assembly; A pair of end caps are respectively disposed at both ends of the housing; bearings are disposed on the end caps, and the two ends of the output shaft assembly pass through and are connected to the corresponding bearings; A conductive element is disposed between the output shaft assembly and the rotor core (2); the conductive element is used to adjust the parasitic capacitance and reduce the potential difference between the inner ring and the outer ring of the bearing.

2. The motor according to claim 1, characterized in that, When the output shaft assembly includes only the output shaft, the conductive element is a conductive sheet, and the conductive sheet is in contact with the rotor core (2).

3. The motor according to claim 1, characterized in that, When the output shaft assembly includes only the output shaft, the conductive element is an additional bushing (1), and the additional bushing (1) and the rotor core (2) are in clearance fit or contact fit.

4. The motor according to claim 3, characterized in that, The outer surface of the additional bushing (1) has a circular or polygonal structure.

5. The motor according to claim 4, characterized in that, The additional bushing (1) includes: The bushing body (11) has a circular structure; Multiple connecting parts (12) are evenly arranged on the outer circumference of the bushing body (11); the connecting parts (12) are correspondingly arranged with each toothed yoke (21) on the rotor core (2).

6. The motor according to claim 5, characterized in that, The connecting part (12) has a groove (121) on the side near the rotor core (2), and the groove (121) is adapted to accommodate the toothed yoke (21).

7. The motor according to claim 6, characterized in that, The bushing body (11) has multiple weight-reducing holes, which are evenly distributed around the circumference of the bushing body (11) and do not penetrate the axial ends of the bushing body (11).

8. The motor according to claim 1, characterized in that, When the output shaft assembly includes an output shaft and an existing bushing mounted on the output shaft, the conductive element is a conductive sheet, and the conductive sheet is in contact with the rotor core (2).

9. The motor according to any one of claims 1 to 8, characterized in that, The conductive element is made of a conductive but non-magnetic material.

10. The motor according to claim 9, characterized in that, The conductive component is made of at least one of the following materials: aluminum, copper, and stainless steel.

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