Insulating bearing sleeve and motor

Abstract

The invention discloses an insulating bearing sleeve and a motor, and relates to the technical field of motors, the insulating bearing sleeve comprises an inner end cover and an outer insulating layer, and a bearing outer ring is installed in the inner end cover; the outer insulating layer is injection-molded on the periphery of the inner end cover, the inner end cover provides rigid support for the bearing outer ring, the creep speed of the outer insulating layer is greatly reduced, and the service life of the motor is prolonged; the outer end cover is provided with an outer cover mounting cavity, the outer cover mounting cavity can accommodate the outer insulating layer, the outer insulating layer forms a circle of insulating structure on the outer ring of the inner end cover, and the outer insulating layer enables radial insulation and axial insulation to be formed between the inner end cover and the outer end cover; the outer insulating layer cuts off a conductive path between the bearing and the outer end cover, and the purpose of electric corrosion prevention of the bearing is achieved.

Description

Technical Field

[0001] This invention relates to the field of electric motor technology, and more particularly to an insulating bearing sleeve and an electric motor. Background Technology

[0002] BLDC (brushless DC motor) motors, due to their advantages of high efficiency, low noise, and long lifespan, have gradually replaced the original brushed DC motors in home appliances such as air conditioners.

[0003] Due to its structure and manufacturing process, shaft voltage is an unavoidable issue in BLDC motors. This shaft voltage is typically generated by multiple factors, including magnetic circuit asymmetry and common-mode voltage (due to high-frequency PWM drive). Normally, the lubricating oil film inside the bearing provides insulation and prevents shaft current formation. However, when the shaft voltage exceeds the insulation threshold of the bearing oil film, the film breaks down, creating a momentary discharge current (shaft current). This current loop is: shaft → bearing inner ring → balls → bearing outer ring → end cap. The localized high temperature caused by this momentary discharge leads to rapid cooling and resolidification of the metal inside the bearing (specifically, the contact points between the inner and outer raceways and the balls), forming microscopic pits. After prolonged operation, these microscopic pits develop into "washboard patterns," causing motor vibration, significantly increasing motor noise, and drastically shortening the motor's lifespan. Therefore, blocking the generation of shaft current is a necessary measure to improve the lifespan of BLDC motors and reduce their vibration and noise.

[0004] To address the challenges posed by shaft current, various improvements or solutions have emerged, including but not limited to improving magnetic circuit imbalance, optimizing motor structure, and optimizing bearing structure. The shortcomings of existing solutions are:

[0005] ① High cost. Blocking shaft current by adjusting the impedance between the stator winding and the bearing (inner) and outer rings requires an additional impedance adjustment device, which greatly increases the cost of the motor.

[0006] ② Limited application scope. While monitoring bearing condition through a monitoring device improves reliability, the large size of such a device is clearly unsuitable for small BLDC motors.

[0007] ③ Complex structure. The shaft current is isolated by anchoring two shafts and filling their end faces with insulating material to prevent contact. Compared to a single-shaft design, this structure is significantly more complex, and the amount and placement of the insulating material are difficult to control. The dual-shaft anchoring method cannot suppress shaft voltage generation; when the shaft voltage exceeds a certain value, it still has the ability to break down the bearing lubricating oil film. Subsequent terminal control systems will require higher voltages, exacerbating the shaft voltage problem.

[0008] For those skilled in the art, simplifying the bearing anti-breakdown structure and reducing costs are technical problems that need to be solved. Summary of the Invention

[0009] The core of this invention is to provide an insulating bearing sleeve, in which the outer insulating layer is injection molded onto the inner end cap. The inner end cap provides rigid support to the outer ring of the bearing, reducing the creep rate of the outer insulating layer. The outer insulating layer cuts off the conductive path between the bearing and the outer end cap, thus breaking the circuit and preventing shaft current from being generated, achieving the purpose of preventing bearing electrolytic corrosion. The specific solution is as follows:

[0010] An insulating bearing sleeve is used in a fixed bearing that supports a rotating shaft, comprising:

[0011] Inner end cap, used for positioning and mounting the outer ring of the bearing;

[0012] An outer insulating layer is disposed on the outer periphery of the inner end cover and at least one end of the inner end cover;

[0013] The inner end cap provides rigid support for the outer insulation layer; the outer insulation layer can be inserted into the outer end cap mounting cavity provided by the outer end cap, and the outer insulation layer forms radial insulation and axial insulation between the inner end cap and the outer end cap.

[0014] Optionally, the inner end cap is made of a material with high creep resistance, including low carbon steel;

[0015] The material of the outer insulation layer is an insulating material.

[0016] Optionally, the inner end cap includes an annular cylinder and a limiting block, the annular cylinder being used to accommodate the outer ring of the bearing, and the limiting block being used to axially position the outer ring of the bearing;

[0017] The outer insulating layer covers the outer surface of the annular cylinder to form radial insulation, and the outer insulating layer covers the outer surface of the limiting block to form an axial covering portion.

[0018] Optionally, a first limiting part is provided on the outer surface of the annular cylinder, and the first limiting part is embedded in the outer insulating layer for circumferentially limiting the outer insulating layer.

[0019] Optionally, the first limiting part is a plurality of protrusions that protrude from the outer surface of the annular cylinder and are arranged at intervals along the circumference.

[0020] Optionally, there is a gap between the first limiting part and the end of the annular cylinder; there is a circumferential spacing between the protrusions of the first limiting part in the circumferential direction; and the outer insulating layer completely covers the protrusions.

[0021] Optionally, it also includes a fixing seat, which is fitted onto the outer periphery of the outer insulating layer;

[0022] The outer insulating layer is disposed between the inner end cover and the fixing base, so that the inner end cover and the fixing base are mutually insulated;

[0023] The mounting base is installed in the outer cover mounting cavity.

[0024] Optionally, the mounting base is made of a material with high creep resistance, including bearing steel.

[0025] Optionally, the height of the inner end cap is greater than the height of the fixing seat, forming a height difference.

[0026] Optionally, a second limiting part is provided on the fixing base, the second limiting part being used to fix and limit the outer insulation layer.

[0027] Optionally, the second limiting portion includes a plurality of through holes spaced apart along the circumference, into which the material of the outer insulating layer is injection molded.

[0028] Optionally, the second limiting part further includes an annular groove arranged circumferentially along the outer surface of the fixing seat, and the material of the outer insulating layer is injected into the annular groove through the through hole.

[0029] Optionally, the second limiting portion includes a plurality of grooves spaced apart along the inner side of the fixing seat.

[0030] Optionally, at least a portion of the groove has a width closer to the outer insulation layer in the radial direction that is smaller than the width farther from the outer insulation layer; and / or, at least a portion of the groove extends axially along the fixing seat, a portion of the groove extends axially to one end of the fixing seat, and a portion of the groove extends axially to the other end of the fixing seat.

[0031] The present invention also provides an electric motor, including an electric motor housing, a rotor, a stator, a rotating shaft and a bearing, wherein the electric motor housing includes an outer end cover, and at least one of the bearings is installed inside the outer end cover;

[0032] The bearing comprises an outer ring and an inner ring.

[0033] An insulating bearing sleeve as described above is provided between the outer ring of the bearing and the outer end cap;

[0034] An inner insulating layer is provided between the inner ring of the bearing and the rotating shaft.

[0035] Optionally, the inner insulation layer further includes an end insulation layer disposed at the end of the shaft, so that the shaft and the outer end cover form axial insulation.

[0036] Optionally, a retaining ring is provided on the side of the rotating shaft near the rotor, and an insulating sheet is provided between the retaining ring and the bearing.

[0037] Optionally, a reinforced connecting portion is provided on the outer surface of the rotating shaft. The reinforced connecting portion has an uneven structure to prevent displacement between the inner insulating layer and the rotating shaft.

[0038] Optionally, the motor housing further includes a plastic-encapsulated housing, and at least one of the bearings is respectively installed inside the outer end cover and the plastic-encapsulated housing;

[0039] An outer casing end cap is provided between the plastic-encapsulated housing and the bearing, and the outer casing end cap is used to assemble the outer ring of the bearing.

[0040] An inner insulating layer is provided between the inner ring of the bearing mounted on the outer casing end cover and the rotating shaft;

[0041] The plastic sealant of the stator is integrally formed with the plastic sealant housing, and the outer end cap is made of metal material.

[0042] This invention provides an insulating bearing sleeve applied to a bearing. The inner ring of the bearing is fitted onto a rotating shaft, and the outer ring is installed inside an inner end cover. An outer insulating layer is injection molded onto the outer circumference of the inner end cover and one end of the inner end cover. The inner end cover provides rigid support for the outer ring of the bearing, significantly reducing the creep rate of the outer insulating layer and increasing the service life of the motor. The outer end cover has an outer cover mounting cavity that can accommodate the outer insulating layer. The outer insulating layer forms an insulating structure around the outer ring of the inner end cover, creating radial and axial insulation between the inner and outer end covers. The outer insulating layer cuts off the conductive path between the bearing and the outer end cover, so the original loop of shaft current is no longer a path, and shaft current is no longer generated, achieving the purpose of preventing bearing electrolytic corrosion.

[0043] This invention provides an electric motor, including a motor housing, a rotor, a stator, a shaft, and a bearing. The motor housing includes an outer end cover, and the bearing is installed inside the outer end cover. An insulating bearing sleeve, as described above, is used between the outer ring of the bearing and the outer end cover to achieve insulation between the bearing and the outer end cover. Furthermore, an inner insulating layer is provided between the inner ring of the bearing and the shaft to achieve insulation between the bearing and the shaft. This motor's bearing achieves double-layer insulation by using an inner insulating layer on the inner ring and an insulating bearing sleeve on the outer ring. This not only meets the current anti-electrolytic corrosion requirements of high-voltage motors but also ensures that the motor's anti-electrolytic corrosion requirements are met even when the subsequent terminal control system uses higher voltages, preventing electrolytic corrosion as the operating voltage increases.

[0044] When the motor is a plastic-encapsulated motor, the motor housing also includes a plastic-encapsulated outer shell. Bearings are mounted on both the outer end cover and the plastic-encapsulated outer shell. The bearing within the plastic-encapsulated outer shell only requires an inner insulation layer between the inner ring of the bearing and the shaft, as the outer ring of the bearing is itself made of insulating material. Therefore, the bearing within the plastic-encapsulated outer shell only needs one inner insulation layer to achieve double insulation. This not only meets the current anti-electrolytic corrosion requirements of high-voltage motors but also ensures that the motor's anti-electrolytic corrosion requirements are met even when higher voltages are required for subsequent terminal control systems, preventing electrolytic corrosion as the operating voltage increases. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is an isometric view of the inner end cap;

[0047] Figure 2A Axonometric drawing of the first embodiment of the mounting bracket;

[0048] Figure 2B Axonometric view of the first embodiment of the outer insulation layer;

[0049] Figure 3A Axonometric view of a second embodiment of the mounting bracket;

[0050] Figure 3B Axonometric view of a second embodiment of the outer insulation layer;

[0051] Figure 4A Axonometric drawing of a third embodiment of the mounting bracket;

[0052] Figure 4B Axonometric view of a third embodiment of the outer insulation layer;

[0053] Figure 5 This is an isometric view of the outer end cap;

[0054] Figure 6 A cross-sectional view of a motor using an insulated bearing sleeve.

[0055] The image includes:

[0056] Inner end cap 10; Inner cap mounting cavity 101; Annular cylinder 110; Limiting block 120; First limiting part 130; Fixing seat 20; Second limiting part 210; Groove 210.1; Through hole 210.2; Annular groove 220; Anti-pull groove 230; Outer insulating layer 30; Protrusion 310; Protruding post 320; Annular body 330; Axial covering part 340; Outer end cap 40; Outer cap mounting cavity 401; Bearing 50; Inner insulating layer 510; Rotating shaft 60; Reinforced connecting part 610; Insulating sheet 620; Plastic-encapsulated shell 70; Shell end cap 710. Detailed Implementation

[0057] To enable those skilled in the art to better understand the technical solution of the present invention, the insulating bearing sleeve and motor of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0058] The insulating bearing sleeve of the present invention is used to fix the bearing 50. The inner ring of the bearing 50 is fitted and fixed to the rotating shaft 60. The bearing 50 serves to support the rotating shaft 60. The insulating bearing sleeve can prevent the bearing 50 from electrolytic corrosion. The bearing has an inner ring, an outer ring, and balls.

[0059] This invention provides an insulating bearing sleeve, including an inner end cap 10, an outer insulating layer 30, and other structures. The inner end cap 10 is a rigid structure and can be made of steel. The inner end cap 10 is used to position and install the outer ring of the bearing. Figure 6 As shown, this illustrates the structure in which the bearing 50 is mounted on the inner end cover 10. Combined with... Figure 1 As shown, the inner end cover 10 is provided with an inner cover mounting cavity 101, which is a cylindrical cavity structure; the outer ring of the bearing is assembled in the inner cover mounting cavity 101, and the outer surface of the outer ring of the bearing contacts the inner wall cylindrical surface of the inner cover mounting cavity 101. The outer ring of the bearing is fixed relative to the inner end cover 10, and the inner ring of the bearing can rotate relative to the inner end cover 10 and the outer ring of the bearing; the inner ring of the bearing is assembled on the rotating shaft 60.

[0060] An outer insulating layer 30 is disposed on the outer periphery of the inner end cover 10 and at least one end of the inner end cover 10, forming radial insulation on the outer periphery of the inner end cover 10 and axial insulation on at least one end of the inner end cover 10. In a specific embodiment, the outer insulating layer 30 is injection molded onto the outer periphery of the inner end cover 10. The outer insulating layer 30 has a ring-shaped structure and a certain thickness in the radial direction, forming a ring of insulating structure on the outer periphery of the inner end cover 10. The inner surface of the outer insulating layer 30 protrudes radially to form a ring-shaped insulating ring, which covers the end of the inner end cover 10 to form axial insulation.

[0061] Combination Figure 5As shown, a specific structure of the outer end cover 40 is illustrated. The outer end cover 40 is fixedly mounted on the motor housing. The outer insulating layer 30 can be inserted into the outer cover mounting cavity 401 of the outer end cover 40, and the outer insulating layer 30 insulates the inner end cover 10 from the outer end cover 40. The outer insulating layer 30 covers the outer periphery and end of the inner end cover 10, so that the inner end cover 10 and the outer end cover 40 form not only radial insulation but also axial insulation. By setting the outer insulating layer 30, the conductive path between the bearing outer ring and the outer end cover 40 is blocked, and the proper loop of shaft current is no longer a path, thus suppressing the generation of shaft current and achieving the purpose of preventing bearing electrolytic corrosion.

[0062] Since the outer insulating layer 30 is injection molded into the outside of the inner end cap 10 to form a ring, the inner end cap 10 is a rigid structure that provides rigid support for the outer insulating layer 30. The inner end cap 10 is located between the outer insulating layer 30 and the outer ring of the bearing, and the outer insulating layer 30 does not directly contact the outer ring of the bearing.

[0063] Creep is the phenomenon that a material slowly undergoes plastic deformation over time under constant stress or load, even if the stress is lower than the material's yield strength. The inner end cap 10 can reduce or even eliminate the adverse effects of creep on the outer insulation layer 30. The insulating materials used in the outer insulation layer 30 include, but are not limited to, resins and plastics, such as PBT engineering plastics (which exhibit certain creep resistance at room temperature and pressure, but their creep resistance decreases rapidly at high temperatures).

[0064] At room temperature, when the bearing is in direct contact with the outer insulation layer, the interference force required by the bearing is provided by the outer insulation layer. According to Newton's third law (action and reaction), the outer insulation layer bears the reaction force from the bearing, meaning it is subjected to stress over a long period. Based on the second law of thermodynamics (heat transfer), the outer insulation layer experiences a temperature rise during motor operation; as a result, creep occurs in the outer insulation layer. With prolonged motor operation, the bearing gradually loosens, motor vibration / noise increases, and the motor's lifespan is significantly reduced.

[0065] This invention provides a rigid inner end cap 10 between the outer insulation layer 30 and the bearing outer ring. The bearing outer ring is fixed to the inner end cap 10's inner cover mounting cavity 101 by an interference fit. Since the outer insulation layer 30 does not directly contact the bearing, according to the second law of thermodynamics, the temperature rise of the outer insulation layer 30 in this invention is lower than that of a solution where the outer insulation layer is directly fitted onto the bearing outer ring. This significantly reduces the creep rate of the outer insulation layer 30, increasing the motor's service life.

[0066] That is, the insulating bearing sleeve provided by the present invention cuts off the shaft current path through the outer insulating layer 30, thereby achieving the purpose of preventing bearing electro-erosion; the inner end cover 10 provides support for the outer insulating layer 30, reducing the creep phenomenon of the outer insulating layer 30 and improving the overall service life.

[0067] Based on the above scheme, combined with Figure 1 As shown, the inner end cap 10 of the present invention includes an annular cylinder 110 and a limiting block 120, which together form an inner cap mounting cavity 101. The annular cylinder 110 has a cylindrical structure, and the limiting block 120 is fixedly disposed on the annular cylinder 110. The limiting block 120 has a circular disc-shaped structure and is perpendicular to the cylindrical surface of the annular cylinder 110. The outer edge of the limiting block 120 is fixed to the annular cylinder 110, and the inner diameter of the limiting block 120 is smaller than the inner diameter of the annular cylinder 110.

[0068] Combination Figure 6 As shown, the outer insulation layer 30 covers the outer surface of the annular cylinder 110 to form radial insulation; the outer insulation layer 30 covers the outer surface of the limiting block 120 to form an axial covering portion 340, which protrudes from the inner surface of the outer insulation layer 30 and is annular, forming axial insulation. The thickness (radial dimension) of the main annular portion of the outer insulation layer 30 is greater than the thickness (axial dimension) of the annular axial covering portion 340. The thickness of each part of the entire outer insulation layer 30 can be set according to the voltage level applied to the motor; the higher the voltage, the greater the thickness.

[0069] It should be noted that, in addition to adopting a complete circular ring structure, the limiting block 120 can also be composed of several independent stop blocks distributed along the circumference.

[0070] The annular cylinder 110 is used to accommodate the outer ring of the bearing. When the bearing 50 is installed in the annular cylinder 110, the outer ring of the bearing and the inner surface of the annular cylinder 110 form an interference fit. A limiting block 120 is provided at one end of the annular cylinder 110, and the other end is used to load and unload the bearing 50. When the bearing 50 is axially loaded into the annular cylinder 110, the limiting block 120 is used to axially position the outer ring of the bearing. When the outer ring of the bearing contacts the limiting block 120, it is axially installed in place. The limiting block 120 axially positions the entire installation position of the bearing 50.

[0071] Combination Figure 1 As shown, a first limiting part 130 is provided on the outer surface of the annular cylinder 110. The first limiting part 130 protrudes from the outer surface of the annular cylinder 110 in the radial direction and is fixed relative to the annular cylinder 110.

[0072] When the outer insulating layer 30 is injection molded onto the outer surface of the annular cylinder 110, the outer insulating layer 30 completely or partially covers the first limiting part 130. After the outer insulating layer 30 is cured, the first limiting part 130 is completely or at least partially embedded in the outer insulating layer 30. By setting the first limiting part 130, the contact area with the outer insulating layer 30 is increased, which can better limit the outer insulating layer 30 circumferentially and make the connection strength between the outer insulating layer 30 and the inner end cap 10 stronger.

[0073] Combination Figure 1 As shown, the annular cylinder 110, the limiting block 120, and the first limiting part 130 can be formed by integral stamping. The limiting block 120 is located at one end of the annular cylinder 110 and protrudes radially from the inner surface of the annular cylinder 110, while the first limiting part 130 is located at the other end of the annular cylinder 110 and protrudes radially from the outer surface of the annular cylinder 110. During processing, the annular cylinder 110, the limiting block 120, and the first limiting part 130 are integrally stamped, resulting in high processing efficiency.

[0074] Combination Figure 1 As shown, in a specific embodiment, the first limiting part 130 is a plurality of protrusions that are spaced apart along the circumference and protrude from the outer surface of the annular cylinder 110. That is, the first limiting part 130 is not a complete structure in the circumferential direction, but is formed by multiple independent parts. When the outer insulating layer 30 is injection molded, the material will fill between the protrusions of the first limiting part 130. The first limiting part 130 and the outer insulating layer 30 not only form circumferential limiting through friction and surface adhesion, but also form blocking limiting through the concave-convex interlocking between the first limiting part 130 and the outer insulating layer 30, so that the circumferential limiting effect of the outer insulating layer 30 is stronger.

[0075] It should be noted that each of the protrusions of the first limiting part 130 has the same shape and is located in the same axial position. The protrusions of the first limiting part 130 may also be distributed in different axial positions or have different shapes. These specific structural forms should all be included within the protection scope of the present invention.

[0076] Furthermore, the present invention should also include the case where the first limiting portion 130 is a complete and independent structure in the circumferential direction, which may be a complete ring or less than one ring. However, the first limiting portion 130 can be configured as a wavy or bent structure to form an interlocking structure with the outer insulating layer 30, which can also improve the circumferential limiting effect of the outer insulating layer 30.

[0077] In one specific embodiment, there is a gap between the first limiting portion 130 and the end of the annular cylinder 110, so that the outer insulating layer 30 completely covers the protrusion; that is, neither the first limiting portion 130 nor the two ends of the annular cylinder 110 are flush. Figure 1 As shown, the first limiting part 130 is disposed at the upper end of the annular cylinder 110, and the upper surface of the first limiting part 130 is lower than the upper end surface of the annular cylinder 110. The first limiting part 130 includes a plurality of protrusions distributed at intervals along the circumference, and there is a gap between each protrusion in the circumferential direction. Based on the above-described structure of the first limiting part 130, when the outer insulating layer 30 is injection molded, the injection molding material is filled to be flush with the upper end of the annular cylinder 110, and the outer insulating layer 30 can completely enclose the first limiting part 130 inside.

[0078] The outer insulating layer 30 completely encloses the first limiting part 130 inside. On the one hand, it increases the contact area between the outer insulating layer 30 and the first limiting part 130, making the circumferential limiting more stable. On the other hand, if the first limiting part 130 is flush with the upper end face of the annular cylinder 110, the upper surface of the outer insulating layer 30 needs to form more flush seams with the first limiting part 130, making it easier to generate burrs during injection molding. The outer insulating layer 30 completely enclosing the first limiting part 130 inside can reduce the generation of burrs.

[0079] Combination Figure 2A As shown, the insulating bearing sleeve of the present invention also includes an annular fixing seat 20. The fixing seat 20 is a cylindrical rigid structure. The fixing seat 20 is fitted onto the outer periphery of the outer insulating layer 30, and the fixing seat 20 provides rigid support to the outer insulating layer 30.

[0080] The inner diameter of the fixing seat 20 is larger than the outer diameter of the inner end cover 10, and the outer insulating layer 30 is filled between the inner end cover 10 and the fixing seat 20. During production, the fixing seat 20 is fitted onto the outer circumference of the inner end cover 10, and insulating material is filled into the annular gap between the fixing seat 20 and the inner end cover 10. After curing, the outer insulating layer 30 is formed. The fixing seat 20 forms the outer surface of the outer insulating layer 30, and the inner end cover 10 forms the inner surface of the outer insulating layer 30. The outer insulating layer 30 insulates the inner end cover 10 and the fixing seat 20 from each other.

[0081] The fixing seat 20 is installed in the outer cover mounting cavity 401 of the outer end cover 40. The fixing seat 20 helps to reduce the creep of the outer insulation layer 30. The fixing seat 20 should be made of a rust-proof / rust-resistant, corrosion-resistant material with high creep resistance, such as bearing steel; the inner end cover 10 should be made of a material with high creep resistance, such as low carbon steel; the outer insulation layer 30 should be made of a material with good insulation properties, such as PBT engineering plastic; the outer end cover can be made of materials such as cast aluminum. Through the limiting effect of the rigid inner end cover 10 and the rigid fixing seat 20, the creep effect on the outer insulation layer 30 is significantly reduced compared to existing technical solutions.

[0082] Creep is time-dependent and intensifies with increasing temperature. As mentioned above, the outer insulation layer 30 is typically made of polymer materials such as resin / plastic. Microscopically, polymer materials are generally connected by covalent bonds to form long-chain structures with relatively weak van der Waals forces. Under long-term stress, the molecular chains will slip or relax, leading to irreversible plastic deformation, i.e., creep. Metals, on the other hand, are connected by metallic bonds, which are strong chemical bonds, with bond energies hundreds of times greater than van der Waals forces. Therefore, the creep resistance of metals is far superior to that of polymers such as resin / plastic. The outer end cover material of existing motors is usually cast aluminum. Microscopically, the self-diffusion activation energy of aluminum is much lower than that of bearing steel (the material of the mounting base 20, which uses rust-resistant / anti-rust / high corrosion-resistant materials such as bearing steel; bearing steel is used as an example here). This means that at the same temperature, the diffusion rate of iron atoms is much lower than that of aluminum atoms, fundamentally suppressing the microscopic driving force of creep. In fact, cast aluminum is not only far lower than bearing steel in terms of self-diffusion activation energy, but also less stable in terms of microstructure (aluminum has a face-centered cubic structure, while steel has a body-centered tetragonal structure; the former has higher slip properties than the latter, meaning it is easier to generate slip at the molecular level).

[0083] In summary, when the outer insulation layer is in direct contact with the outer end cap, the cast aluminum end cap / outer insulation layer will undergo creep at room temperature, and this creep phenomenon will intensify as the motor operates. When the creep reaches a certain level, the outer end cap and the outer insulation layer will no longer be tightly connected, the outer insulation layer will loosen, the motor vibration / noise will increase significantly, and the motor's service life will be greatly reduced. By adding a fixing seat 20 between the outer insulation layer 30 and the outer end cap 40, the creep rate of the outer insulation layer 30 is reduced. Furthermore, based on the limiting effect of the inner end cap 10 and the fixing seat 20, even if the outer insulation layer 30 undergoes some creep, its impact is greatly reduced, and the motor's service life is increased.

[0084] From a macroscopic perspective, creep in materials is generally related to temperature and applied constant stress. However, once the temperature reaches the material's creep-sensitive temperature, temperature becomes the primary factor in creep occurrence. That is, even under constant stress below the material's allowable stress, creep can still occur. Numerous academic studies have shown that the creep-sensitive temperature of metals and ceramics is typically 50% of their melting point, while the creep-sensitive temperature of PBT (engineering plastic) is usually slightly higher than its glass transition temperature. The glass transition temperature of conventional PBT is typically around 30℃, while the melting points of cast aluminum / bearing steel are typically around 600℃ / 1450℃. Clearly, the creep-sensitive temperature increases sequentially from PBT to cast aluminum to bearing steel, meaning that bearing steel has a much higher creep resistance than PBT and cast aluminum. Conventional PBT may experience significant temperature-induced creep even at room temperature. In summary, creep is an inherent characteristic of materials such as metals and polymers, but different materials have different creep resistance. Therefore, adding a fixing seat 20 between the outer end cap 40 and the outer insulation layer 30 can effectively reduce the creep rate of the outer insulation layer 30 and significantly reduce the adverse effects of creep.

[0085] In one specific embodiment, a second limiting part 210 is provided on the inner surface of the fixing base 20. The second limiting part 210 is used to fix and limit the outer insulating layer 30. By providing the second limiting part 210, the connection strength between the fixing base 20 and the outer insulating layer 30 is strengthened, preventing the fixing base 20 and the outer insulating layer 30 from loosening, such as circumferential rotation, radial displacement or axial displacement.

[0086] The second limiting part 210 can adopt different structural forms, such as Figure 2A , Figure 4A As shown, in this embodiment, the second limiting part 210 includes a plurality of grooves 210.1 spaced circumferentially on the inner surface of the fixing seat 20. Each groove 210.1 is a radially recessed structure, and the radial recess depth of the groove 210.1 is less than the wall thickness of the fixing seat 20. When the insulating material is filled between the fixing seat 20 and the inner end cap 10, the insulating material enters the grooves 210.1. After curing to form the outer insulating layer 30, a plurality of protrusions 310 are formed on the outer surface of the outer insulating layer 30, such as... Figure 2B As shown, the protrusion 310 and the groove 210.1 form a nested fit, which increases the circumferential limiting resistance between the outer insulation layer 30 and the fixing seat 20.

[0087] Combination Figure 2A , Figure 2B As shown, the length of the groove 210.1 extends axially along the fixing base 20, and the length of the groove 210.1 is less than the axial height of the fixing base 20. A portion of the groove 210.1 extends axially to one end of the fixing base 20, and a portion of the groove 210.1 extends axially to the other end of the fixing base 20. Figure 2A , Figure 2BIn the structure shown, two adjacent grooves 210.1 extend alternately to both ends of the fixing seat 20, making the axial limiting effect more uniform. Since the length of the groove 210.1 is less than the axial height of the fixing seat 20, after the outer insulating layer 30 is injection molded, the protrusion 310 and the groove 210.1 not only form circumferential limiting but also have an axial limiting function, so neither the fixing seat 20 nor the inner end cap 10 can move axially relative to the outer insulating layer 30.

[0088] Combination Figure 3A As shown, in another embodiment provided by the present invention, the second limiting part 210 includes a plurality of through holes 210.2 spaced apart along the circumference, and the through holes 210.2 penetrate the sidewall of the fixing seat 20 radially. When insulating material is filled, it enters the through holes 210.2, and after curing to form the outer insulating layer 30, it combines with... Figure 3B As shown, the portion entering the through hole 210.2 forms a protrusion 320. The protrusion 320 and the through hole 210.2 form a concave-convex nested fit, which not only achieves circumferential limiting but also axial limiting.

[0089] Furthermore, combining Figure 3A As shown, the second limiting part 210 also includes an annular groove 220 arranged circumferentially on the outer surface of the fixing seat 20. The material of the outer insulating layer 30 is injected into the annular groove 220 through the through hole 210.2 to form an annular body 330. The annular body 330 and the protrusion 320 are integrally formed. During injection molding, the insulating material enters the annular groove 220 through the through hole 210.2 and finally forms the annular body 330. After the injection molding is completed, during the cooling process, the material shrinks due to its material properties. The annular body 330 formed by the structure of the through hole 210.2 and the annular groove 220 will prevent the radial shrinkage of the material during shrinkage, thereby firmly fixing the outer insulating layer 30 to the fixing seat 20 and preventing loosening.

[0090] In addition to adopting Figure 3A In addition to the cooling shrinkage forms shown, other methods such as... Figure 4A , Figure 4B In the structure shown, at least a portion of the grooves 210.1 on the inner surface of the fixing base 20 have a varying width in the radial direction, with the width of the groove 210.1 near the outer insulating layer 30 being smaller than the width of the groove away from the outer insulating layer. This portion of the groove 210.1 may have a trapezoidal cross-section. Figure 4B ) or a "T" shaped cross section ( Figure 4A During injection molding, the insulating material enters the groove 210.1 with varying width. After cooling and solidification, the part that enters the groove 210.1 with varying width forms an anti-pull block. The anti-pull block forms radial tension on the outer insulating layer 30, which can also firmly fix the outer insulating layer 30 to the fixing seat 20, preventing it from becoming loose.

[0091] There is a certain height difference between the inner end cap 10 and the fixing base 20. The height (axial dimension) of the fixing base 20 is smaller than the height (axial dimension) of the inner end cap 10. The advantage of this structure is that it improves insulation performance and reliability. Breakdown refers to the destructive discharge that occurs inside the insulator under the action of an electric field, resulting in a decrease in insulation resistance and an increase in current. The voltage at which this occurs is called the breakdown voltage. The breakdown voltage increases as the distance between the two conductors increases. This can be indirectly confirmed by the phenomenon of tip discharge. Under the same voltage, the further apart the two pointed conductors are, the less likely tip discharge will occur. In summary, when there is a height difference between the inner end cap 10 and the fixing base 20, the shortest breakdown path increases, the breakdown voltage increases, and the insulation performance improves. In practice, in order to control the size and cost of the end cap, the height difference between the inner end cap 10 and the fixing base 20 and the thickness of the outer insulation layer 30 can be appropriately reduced or thinned while meeting the insulation performance requirements.

[0092] This invention also provides an electric motor, which includes a motor housing, a rotor, a stator, a shaft 60, and bearings 50. The motor housing includes an outer end cover 40, which has a hollow shell structure. The inner cavity of the motor housing is used to install the rotor, stator, coils, bearings, and other structures. A portion of the shaft structure is located within this cavity. At least one bearing 50 is installed inside the outer end cover 40, typically two bearings 50 are assembled in the motor housing. Each bearing 50 includes an outer ring and an inner ring. An insulating bearing sleeve is provided between the outer ring and the outer end cover 40. This motor can cut off the conductive circuit between the shaft 60 and the outer end cover 40, achieving the aforementioned anti-electro-erosion effect. An inner insulating layer 510 is provided between the inner ring of the bearing and the shaft 60. The inner insulating layer 510 is coated on the outer surface of the shaft 60 and fills the gap between the inner ring of the bearing 50 and the shaft 60, achieving insulation. Here, "inner" means that the inner insulating layer 510 is closer to the shaft 60 than the outer insulating layer 30.

[0093] In this motor, the aforementioned insulating bearing sleeve is used between the outer ring of bearing 50 and the outer end cover 40 to achieve insulation between bearing 50 and the outer end cover 40; an inner insulating layer 510 is provided between the inner ring of bearing 50 and the shaft 60 to achieve insulation between bearing 50 and the shaft 60. The double-layer insulation of bearing 50 achieved through the inner insulating layer 510 and the insulating bearing sleeve provides a stronger insulation effect. This not only meets the current anti-electrolytic corrosion requirements of high-voltage motors but also ensures the bearing's anti-electrolytic corrosion purpose even when higher voltages are used in subsequent motor control, preventing electrolytic corrosion as the operating voltage increases.

[0094] After the inner insulating layer 510 is coated and cured on the shaft 60, the inner insulating layer 510 forms radial insulation between the inner ring of the bearing 50 and the shaft 60; combined Figure 6As shown, two bearings 50 are installed on the shaft 60 of the entire motor. An inner insulation layer 510 is formed between the inner ring of the two bearings 50 and the shaft 60. The inner insulation layer 510 is coated on the end of the shaft 60 to form an end insulation layer, so that the shaft 60 and the outer end cover 40 form axial insulation, ensuring comprehensive insulation protection.

[0095] Combination Figure 6 As shown, a reinforced connection portion 610 is provided on the outer surface of the rotating shaft 60. The reinforced connection portion 610 has an uneven surface to enhance the connection strength with the inner insulation layer 510 and prevent displacement between the inner insulation layer 510 and the rotating shaft 60. The reinforced connection portion 610 includes, but is not limited to, a sawtooth structure, a threaded structure, and a corrugated structure. The reinforced connection portion 610 has a certain degree of unevenness to improve the adhesion of the inner insulation layer 510 to the rotating shaft 60 and maintain the corresponding mechanical properties of the rotating shaft 60.

[0096] Combination Figure 6 As shown, an annular groove is provided on the outer surface of the rotating shaft 60, and an open retaining ring is installed in the annular groove. The open retaining ring is used to block the bearing 50 to limit the axial position of the bearing 50. An insulating sheet 620 with an annular structure is provided between the open retaining ring of the rotating shaft 60 and the bearing 50.

[0097] In a conventional motor, the open retaining ring mounted on the shaft 60 is in direct contact with the bearing. In this case, when the current path between the shaft 60 and the bearing 50 is blocked, the current will form another loop: shaft → open retaining ring → bearing. Therefore, an insulating sheet 620 needs to be added between the open retaining ring and the bearing 50 to block this loop. The motor has two bearings 50, and insulating sheets 620 can be installed on both bearings 50.

[0098] The present invention also provides a motor, such as Figure 6 As shown, the motor includes a motor housing, a rotor, a stator, a shaft 60, and a bearing 50. The motor housing includes an outer end cover 40 and a plastic-encapsulated housing 70. The outer end cover 40 and the plastic-encapsulated housing 70 are fixedly assembled by bolts or other means. The outer end cover 40 and the plastic-encapsulated housing 70 are connected to form a hollow shell structure. The inner cavity of the motor housing is used to install the rotor, stator, coils, bearings, and other structures. A partial structure of the shaft is located in this cavity.

[0099] The outer end cover 40 and the plastic-encapsulated housing 70 are each fitted with at least one bearing 50, meaning the rotating shaft 60 is assembled to the motor housing via at least two bearings 50. Each bearing 50 comprises an outer ring and an inner ring. Figure 6 In the illustrated embodiment, a bearing 50 is mounted on the outer end cap 40 and a bearing 50 is mounted on the plastic-encapsulated housing 70.

[0100] In this motor, the aforementioned insulating bearing sleeve is provided between the outer end cover 40 and the outer ring of the bearing. This motor can cut off the conductive circuit between the rotating shaft 60 and the outer end cover 40, thereby achieving the aforementioned anti-electro-erosion technical effect.

[0101] Combination Figure 6 As shown, an inner insulating layer 510 is provided between the inner ring of the bearing 50 and the shaft 60. The inner insulating layer 510 is coated on the outer surface of the shaft 60 and fills the gap between the inner ring of the bearing 50 and the shaft 60 to achieve insulation. Here, "inner" means that the inner insulating layer 510 is closer to the shaft 60 than the outer insulating layer 30.

[0102] After the inner insulating layer 510 is coated and cured on the shaft 60, the inner insulating layer 510 forms radial insulation between the inner ring of the bearing 50 and the shaft 60; combined Figure 6 As shown, two bearings 50 are installed on the shaft 60 of the entire motor. An inner insulation layer 510 is formed between the inner ring of the two bearings 50 and the shaft 60. The inner insulation layer 510 is coated on the end of the shaft 60 to form an end insulation layer, so that the shaft 60 and the outer end cover 40 form axial insulation, ensuring comprehensive insulation protection.

[0103] In the motor structure of this invention, the plastic-encapsulated housing 70 is made of insulating material, and the plastic-encapsulated stator is integrally formed with the plastic-encapsulated housing 70; the outer end cover 40 is made of metal material to ensure stable support performance. At least one bearing 50 is installed in both the outer end cover 40 and the plastic-encapsulated housing 70.

[0104] Combination Figure 6 As shown, a housing end cap 710 is provided on the plastic-encapsulated housing 70. The housing end cap 710 is embedded in the plastic-encapsulated housing 70 and is used to assemble the outer ring of the bearing 50.

[0105] An inner insulating layer 510 is provided between the inner ring of the bearing 50 mounted on the outer casing end cover 710 and the rotating shaft 60. Since the plastic-encapsulated outer casing 70 itself is an insulating material, there is no need to provide the aforementioned outer insulating layer 30 between the outer casing end cover 710 and the bearing 50, so that the bearing inside the plastic-encapsulated outer casing can achieve double insulation.

[0106] In summary, when the motor is a plastic-encapsulated motor, the motor housing includes a plastic-encapsulated housing 70 and an outer end cover 40, and bearings 50 are respectively installed in the plastic-encapsulated housing 70 and the outer end cover 40. The bearing 50 inside the plastic-encapsulated housing 70 only needs an inner insulating layer 510 between its inner ring and the shaft 60 to achieve a double-layer insulation effect. The bearing 50 inside the outer end cover 40 has an inner insulating layer 510 between its inner ring and the shaft 60, and an insulating bearing sleeve is installed between its outer ring and the outer end cover 40 to form a double-layer insulation effect. Therefore, the bearing 50 in the plastic-encapsulated motor, whether in the plastic-encapsulated housing 70 or the outer end cover 40, can achieve a double anti-electro-erosion effect. When the motor is a plastic-encapsulated motor, the cost of the insulating bearing sleeve for the bearing 50 in the plastic-encapsulated housing 70 is also saved.

[0107] A reinforced connection portion 610 is provided on the outer surface of the rotating shaft 60 to enhance the connection strength between the rotating shaft 60 and the two inner insulation layers 510, so that the rotating shaft 60 and the two bearings 50 have a stronger connection strength.

[0108] In summary, the core advantage of the insulating bearing sleeve and motor of the present invention lies in its ability to efficiently solve the problem of bearing electro-erosion while ensuring the original performance of the motor, thereby fundamentally blocking the shaft current.

[0109] Compared with existing electro-erosion solutions, this invention has made significant breakthroughs: on the one hand, it overcomes the high cost drawbacks of traditional anti-electro-erosion methods—it does not require replacing metal bearings with ceramic bearings or increasing the impedance between the stator winding and the bearing; on the other hand, it has more advantages than traditional anti-electro-erosion structures, with a simple and reliable structural design, simple manufacturing process, and can minimize the impact on production output.

[0110] Furthermore, this anti-electro-optical corrosion structure boasts outstanding production efficiency and can be standardized into multiple specifications. This characteristic not only significantly improves product consistency but also further optimizes the production process and enhances efficiency. Overall, this invention achieves breakthrough improvements in economy, practicality, and production adaptability, providing a superior solution for the field of motor anti-electro-optical corrosion.

[0111] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An insulating bearing sleeve, characterized in that The application is applied to a fixed bearing (50) supporting a rotating shaft (60), comprising: an inner end cover (10) for positioning and installing a bearing outer ring of the bearing (50); an outer insulation layer (30) arranged on an outer periphery of the inner end cover (10) and at least one end of the inner end cover (10); wherein the inner end cover (10) provides rigid support for the outer insulation layer (30); the outer insulation layer (30) can be placed in an outer cover installation cavity (401) arranged on the outer end cover (40), and the outer insulation layer (30) forms radial insulation and axial insulation between the inner end cover (10) and the outer end cover (40).

2. The insulating bearing sleeve of claim 1, wherein, The inner end cover (10) is made of a material with high anti-cracking ability, and the material of the inner end cover (10) includes low-carbon steel. The material of the outer insulation layer (30) is an insulating material.

3. The insulating bearing sleeve of claim 1, wherein, The inner end cover (10) includes an annular cylinder (110) for accommodating the bearing outer ring and a limiting block (120) for axially positioning the bearing outer ring. The outer insulation layer (30) covers the outer surface of the annular cylinder (110) to form radial insulation, and covers the outer surface of the limiting block (120) to form an axial covering part (340).

4. The insulating bearing sleeve of claim 3, wherein, The outer surface of the annular cylinder (110) is provided with a first limiting part (130) embedded in the outer insulation layer (30) for circumferentially limiting the outer insulation layer (30).

5. The insulating bearing sleeve of claim 4, wherein, The first limiting part (130) is a plurality of protrusions protruding from the outer surface of the annular cylinder (110) arranged at intervals along the circumference.

6. The insulating bearing sleeve of claim 5, wherein, The first limiting part (130) has a spacing with the end of the annular cylinder (110); each protrusion of the first limiting part (130) has a circumferential spacing in the circumferential direction; and the outer insulation layer (30) completely wraps the protrusions.

7. The insulating bearing sleeve according to any one of claims 1 to 6, characterized in that Further comprising a fixing seat (20) sleeved on the outer periphery of the outer insulation layer (30); The outer insulation layer (30) is arranged between the inner end cover (10) and the fixing seat (20) to insulate the inner end cover (10) and the fixing seat (20) from each other; The fixing seat (20) is installed in the outer cover installation cavity (401).

8. The insulating bearing sleeve of claim 7, wherein, The fixing seat (20) is made of a material with high anti-cracking ability, and the material of the fixing seat (20) includes bearing steel.

9. The insulating bearing sleeve of claim 7, wherein, The height of the inner end cover (10) is greater than the height of the fixing seat (20) to form a height difference.

10. The insulating bearing sleeve of claim 7, wherein, The fixing seat (20) is provided with a second limiting part (210) for fixedly limiting the outer insulation layer (30).

11. The insulating bearing sleeve of claim 10, wherein, The second limiting part (210) includes a plurality of through holes (210.2) arranged at intervals along the circumference, and the material of the outer insulation layer (30) is injection molded into the through holes (210.2).

12. The insulating bearing sleeve of claim 11, wherein, The second limiting part (210) further includes an annular groove (220) arranged circumferentially along the outer surface of the fixing seat (20), and the material of the outer insulation layer (30) is injection molded into the annular groove (220) through the through holes (210.2).

13. The insulating bearing sleeve of claim 10, wherein, The second limiting part (210) comprises a plurality of grooves (210.1) arranged at intervals along the inner side of the fixing base (20).

14. The insulating bearing sleeve of claim 13, wherein, At least part of the grooves (210.1) has a width smaller on the side close to the outer insulation layer than on the side away from the outer insulation layer in the radial direction; and / or, at least part of the grooves (210.1) extends along the axial direction of the fixing base (20), part of the grooves (210.1) extends to one end of the fixing base (20) in the axial direction, and part of the grooves (210.1) extends to the other end of the fixing base (20) in the axial direction.

15. An electric machine characterized by The motor housing comprises an outer end cover (40), and at least one bearing (50) is mounted inside the outer end cover (40); The bearing (50) comprises a bearing outer ring and a bearing inner ring; An insulating bearing sleeve as claimed in any one of claims 1 to 14 is arranged between the bearing outer ring and the outer end cover (40); An inner insulation layer (510) is arranged between the bearing inner ring and the rotating shaft (60).

16. The electric machine of claim 15, wherein, The inner insulation layer (510) further comprises an end insulation layer arranged at the end of the rotating shaft (60), so that the rotating shaft (60) and the outer end cover (40) are axially insulated.

17. The electric machine of claim 15, wherein, A retaining ring is arranged on the side of the rotating shaft (60) close to the rotor, and an insulating sheet (620) is arranged between the retaining ring and the bearing (50).

18. The electric machine of claim 15, wherein, The outer surface of the rotating shaft (60) is provided with a reinforced connecting part (610) having a concave-convex structure, which is used to prevent displacement of the inner insulation layer (510) and the rotating shaft (60).

19. The electric machine of any of claims 15-18, wherein, The motor housing further comprises a plastic encapsulation housing (70), and at least one bearing (50) is mounted in the plastic encapsulation housing (70) and the outer end cover (40) respectively; An outer shell end cover (710) is arranged between the plastic encapsulation housing (70) and the bearing (50), and is used to assemble the bearing outer ring of the bearing (50); An inner insulation layer (510) is arranged between the bearing inner ring of the bearing (50) assembled by the outer shell end cover (710) and the rotating shaft (60); The plastic encapsulation part of the plastic encapsulation housing (70) is integrally formed with the plastic encapsulation part of the plastic encapsulation housing (70), and the outer end cover (40) is made of metal material.

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