An electromagnetically cleaned lubricated bearing for traction motors and its design method

Abstract

This invention belongs to the field of electrified rail transit and provides an electromagnetic purification and lubrication bearing for traction motors and its design method. The device includes a bearing and an electromagnet. The bearing includes an outer ring, an inner ring, and at least two steel balls. The steel balls are disposed between the outer ring and the inner ring, and grease is filled between the inner ring and the outer ring. The steel balls are in contact with the inner ring and the outer ring respectively. At least two electromagnets are provided, and the electromagnets are evenly distributed along the circumference of the bearing. The electromagnets are disposed between two adjacent steel balls, and the direction of the magnetic field generated by the electromagnets is the same as the circumference of the bearing. This invention not only eliminates the need for regular maintenance and filter replacement, but also improves the efficiency of removing metal impurities, reduces maintenance costs, and improves the operating efficiency of trains.

Description

Technical Field

[0001] This invention relates to the field of electrified rail transit technology, and more specifically, to an electromagnetically purified lubricated bearing for traction motors and its design method. Background Technology

[0002] In the field of electrified rail transit, the performance and reliability of traction motor bearings are crucial, and metallic impurities in lubricating grease are a key factor affecting bearing life and performance. These metallic impurities mainly originate from the high-temperature arcs generated by the breakdown of the motor bearing insulation layer under frequent impacts such as lightning overvoltage and wheel-rail rolling arcing overvoltage, causing the surrounding metal to melt and peel off. Metallic impurities accelerate bearing wear, alter the physicochemical properties of lubricating grease, block lubrication channels, cause abnormal current conduction, leading to electrochemical corrosion and mechanical wear of the bearing, increasing vibration and noise, and even causing sudden bearing failure.

[0003] Currently, solutions to this problem include improving bearing materials and manufacturing processes, using high-precision filtration devices, and regularly cleaning and replacing lubricating grease. However, these solutions have limitations. For example, improving materials and processes is costly and cannot fundamentally solve the problem; high-precision filtration devices have limited effectiveness in removing fine particles and are costly to maintain; and regularly cleaning and replacing lubricating grease is cumbersome and affects train operating efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide an electromagnetically purified lubricated bearing for traction motors and its design method, thereby improving the aforementioned problems. To achieve the above objective, the technical solution adopted by this invention is as follows:

[0005] On one hand, this application provides an electromagnetic purification and lubrication bearing for a traction motor, including a bearing and an electromagnet. The bearing includes an outer ring, an inner ring, and at least two steel balls. The steel balls are disposed between the outer ring and the inner ring, and grease is filled between the inner ring and the outer ring. The steel balls are in contact with the inner ring and the outer ring respectively. At least two electromagnets are provided, and the electromagnets are evenly distributed along the circumferential direction of the bearing. The electromagnets are disposed between two adjacent steel balls, and the direction of the magnetic field generated by the electromagnets is the same as the circumferential direction of the bearing.

[0006] On the other hand, this application provides a design method for an electromagnetically cleaned lubricated bearing for a traction motor, the method comprising:

[0007] Obtain the bearing's geometric parameters, preset magnetic field strength constraints, and temperature rise constraints;

[0008] The geometric parameters of the electromagnet are calculated under the preset magnetic field strength constraint and temperature rise constraint, and the calculation results are obtained.

[0009] The number of electromagnets is determined based on the bearing's geometric parameters and the electromagnet diameter included in the calculation results.

[0010] Based on the constraints of magnetic field superposition and mechanical interference, the minimum layout spacing between adjacent electromagnets is calculated, and the electromagnet spacing is obtained.

[0011] Based on the electromagnet geometric data, the number of electromagnets, and the spacing between the electromagnets, a spatial arrangement scheme for the electromagnets in the circumferential direction of the target bearing is constructed.

[0012] The beneficial effects of this invention are as follows:

[0013] This invention uses electromagnets evenly distributed along the circumference of the bearing to form a continuous closed magnetic field when energized, which directionally adsorbs metal debris in the lubricating grease. This not only eliminates the need for regular maintenance and filter replacement, but also improves the efficiency of removing metal impurities, reduces maintenance costs, and improves the operating efficiency of the train.

[0014] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing embodiments of the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the electromagnetic purification and lubrication bearing structure for a traction motor as described in an embodiment of the present invention.

[0017] The markings in the diagram are: 1. Outer ring; 2. Inner ring; 3. Steel ball; 4. Grease; 5. Electromagnet; 6. Cage. Detailed Implementation

[0018] 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, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0019] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0020] Example 1

[0021] like Figure 1 As shown, this embodiment provides an electromagnetically purified lubricated bearing for a traction motor, including a bearing and an electromagnet 5. The bearing includes an outer ring 1, an inner ring 2, and at least two steel balls 3. The steel balls 3 are disposed between the outer ring 1 and the inner ring 2. The space between the inner ring 2 and the outer ring 1 is filled with grease 4. The steel balls 3 are in contact with the inner ring 2 and the outer ring 1 respectively. At least two electromagnets 5 are provided, and the electromagnets 5 are evenly distributed along the circumference of the bearing. The electromagnets 5 are disposed between two adjacent steel balls 3, and the direction of the magnetic field generated by the electromagnets 5 is the same as the circumferential direction of the bearing.

[0022] This invention solves the problem of metal contamination in bearing grease caused by overvoltage impacts in electrified rail transit by uniformly arranging electromagnets 5 between adjacent steel balls 3 in the traction motor bearing. The circumferential magnetic field generated by these electromagnets directionally adsorbs metal debris from the grease. This inhibits electrochemical corrosion and mechanical wear of the bearing, extending bearing life from the conventional design of 1-2 years to 3-5 years, and improving the operational reliability of the traction motor. Specifically, it addresses the problem of metal debris generated by the breakdown of the bearing insulation layer due to impacts such as lightning overvoltage and wheel-rail rolling arcing overvoltage. The continuous closed magnetic field generated by the electromagnets 5 actively adsorbs metal particles such as Fe and Cu in the grease, reducing contamination and preventing abrasive wear, changes in the physicochemical properties of the grease, and blockage of lubrication channels caused by debris. Simultaneously, the layout and magnetic field direction design of the electromagnets 5 can block the conduction path of shaft current in the grease 4, remove conductive debris, reduce the density of bearing electrolytic corrosion points, protect the insulating coating, and reduce the concentration of alternating stress between the rolling elements and the raceway by adsorbing debris. This controls the radial clearance change rate of the bearing, prevents the propagation of microcracks, and improves the bearing fatigue life.

[0023] It should be noted that the inner ring of the electromagnet 5 is equipped with an annular magnetic adsorption groove. When energized, debris is attracted to the annular magnetic adsorption groove by the magnetic field. After the power is turned off, it can be manually removed through the detachable filter screen, which improves the cleaning efficiency.

[0024] In one specific embodiment of this disclosure, a retainer 6 is provided between the inner ring 2 and the outer ring 1. The retainer 6 has at least two first through holes, which are evenly distributed along the circumference. The retainer 6 can fix the circumferential distribution positions of the steel ball 3 and the electromagnet 5, ensuring that they maintain a uniform distance during bearing operation and avoiding mechanical interference. The first through holes are evenly distributed along the circumference and are used to install the steel ball 3, allowing the steel ball 3 to roll stably between the inner and outer rings of the bearing. At the same time, they provide a reference positioning for the layout of the electromagnet 5, ensuring the uniformity of the magnetic field coverage.

[0025] In one specific embodiment of this disclosure, a second through hole is provided between the two first through holes. The diameter of the second through hole is the same as that of the electromagnet 5. The diameter of the second through hole matches that of the electromagnet 5 for precise installation of the electromagnet 5, so that the electromagnet 5 is evenly embedded in the gap between adjacent steel balls 3 along the circumferential direction of the bearing, ensuring that a continuous closed magnetic field is formed after energization, so as to effectively cover the grease circulation area and realize the directional adsorption of metal debris.

[0026] In one specific embodiment of this disclosure, the outer ring 1 has a first groove on the side near the steel ball 3, and the inner ring 2 has a second groove on the side near the steel ball 3. The steel ball 3 contacts both the first and second grooves. The first groove on the outer ring 1 and the second groove on the inner ring 2 provide a rolling track for the steel ball 3, reducing friction and wear between the steel ball 3 and the inner and outer rings. This also regulates the movement trajectory of the steel ball 3, ensuring smooth bearing operation. Furthermore, the groove structure also helps to evenly distribute grease within the bearing, improving lubrication.

[0027] In one specific embodiment of this disclosure, the two ends of the electromagnet 5 are in contact with the first slide groove and the second slide groove respectively. This allows the electromagnet 5 to be fixed between the inner and outer rings of the bearing and to share the slide with the steel ball 3. This ensures that the electromagnet 5 maintains a stable position when the bearing rotates at high speed, preventing displacement due to vibration, thereby maintaining the continuity of the magnetic field and the adsorption efficiency.

[0028] Example 2

[0029] This embodiment provides a design method for an electromagnetically cleaned lubricated bearing for a traction motor. The method includes steps S1, S2, S3, S4, and S5, specifically including:

[0030] Step S1: Obtain the bearing's geometric parameters, preset magnetic field strength constraints, and temperature rise constraints.

[0031] In this step, the bearing's geometric parameters are its inner diameter, outer diameter, number of steel balls, and diameter of the steel balls; the preset magnetic field strength constraint is that the magnetic field strength at the center of a single electromagnet is ≥0.35T; and the preset temperature rise constraint is that ΔT≤80℃.

[0032] Step S2: Calculate the geometric parameters of the electromagnet under the preset magnetic field strength constraint and temperature rise constraint, and obtain the calculation results;

[0033] Step S2 further includes steps S21, S22, S23, S24, and S25, which specifically include:

[0034] Step S21: Obtain the vacuum permeability, the relative permeability of the core material, the target magnetic field strength, the core length, and the operating current;

[0035] Step S22: Calculate the number of coil turns based on the vacuum permeability, the relative permeability of the core material, the target magnetic field strength, the core length, and the operating current;

[0036] In this step, the specific formula for calculating the number of coil turns is as follows:

[0037]

[0038] In the above formula, μ0 and μ r These represent the vacuum permeability and the relative permeability of the core material, respectively; B0 represents the target magnetic field strength; I represents the operating current, referring to the current intensity flowing through the electromagnet coil, supplied by the external circuit that powers the electromagnet; l core This indicates the length of the magnetic core, which is the physical length of the magnetic core along its axial direction.

[0039] Step S23: Obtain the saturation magnetic flux density of the magnetic core and the length of the magnetic circuit;

[0040] Step S23 further includes steps S231, S232, and S233, which specifically include:

[0041] Step S231: Based on the geometric parameters of the bearing, determine the model information of the electromagnet suitable for installation on the inner and outer rings of the bearing;

[0042] In this step, the geometric parameters of the corresponding bearing can be obtained based on the electromagnet model information.

[0043] Step S232: Determine the corresponding outer diameter and inner diameter of the magnetic core based on the electromagnet model information;

[0044] Step S233: Calculate the magnetic circuit length based on the outer diameter and inner diameter of the magnetic core.

[0045] In this step, the specific calculation process for the magnetic circuit length is as follows:

[0046]

[0047] In the above formula, l path D represents the magnetic circuit length, which is the total path length of the magnetic flux circulating in a closed magnetic core. i and D o These represent the inner diameter and outer diameter of the magnetic core, respectively.

[0048] Step S24: Calculate the cross-sectional area of ​​the magnetic core based on the saturation magnetic flux density, magnetic circuit length, and number of coil turns;

[0049] In this step, the specific calculation process for the cross-sectional area of ​​the magnetic core is as follows:

[0050]

[0051] In the above formula, A represents the cross-sectional area of ​​the magnetic core; N represents the number of coil turns; B sat This indicates the saturation magnetic flux density of the magnetic core.

[0052] Step S25: Calculate the diameter of the electromagnet based on the cross-sectional area of ​​the magnetic core.

[0053] In this step, the specific formula for calculating the diameter of the electromagnet is as follows:

[0054]

[0055] In the above formula, d em A represents the diameter of the electromagnet; A represents the cross-sectional area of ​​the magnetic core.

[0056] Step S3: Determine the number of electromagnets based on the geometric parameters of the bearing and the electromagnet diameter included in the calculation results;

[0057] Step S3 further includes steps S31, S32, S33, and S34, which specifically include:

[0058] Step S31: Determine the bearing inner diameter, bearing outer diameter, number of steel balls, and steel ball diameter based on the bearing's geometric parameters, and calculate the effective magnetic field coverage perimeter.

[0059] In this step, the specific calculation process for the effective magnetic field coverage perimeter is as follows:

[0060]

[0061] In the above formula, D1 and D2 represent the bearing inner diameter and bearing outer diameter, respectively; N0 represents the number of steel balls; d ball This indicates the diameter of the steel ball.

[0062] Step S32: Calculate the product of the first preset value and the diameter of the electromagnet to obtain the effective coverage radius of a single electromagnet;

[0063] λ eff =1.8d em

[0064] In the above formula, λ eff d represents the effective coverage radius of a single electromagnet. em This indicates the diameter of the electromagnet.

[0065] Step S33: Calculate the product of the preset safety margin coefficient and the effective magnetic field coverage perimeter to obtain the first calculation result;

[0066] Step S34: Calculate the ratio of the first calculation result to the effective coverage radius to obtain the number of electromagnets.

[0067] In this step, the specific formula for calculating the number of electromagnets is as follows:

[0068]

[0069] In the above formula, M represents the first calculation result, specifically: M = k·L, where k represents the safety margin coefficient and L represents the effective magnetic field coverage perimeter.

[0070] In this embodiment, the optimal number of electromagnets is determined by quantitative calculation to ensure that the magnetic field continuously covers the bearing circumference without blind spots, avoiding magnetic field interruption due to insufficient quantity or mechanical interference due to excessive quantity, thus achieving a balance between magnetic field adsorption efficiency and bearing structural safety.

[0071] Step S4: Based on the magnetic field superposition constraint and mechanical interference constraint, calculate the minimum layout spacing between adjacent electromagnets to obtain the electromagnet spacing;

[0072] Step S4 further includes steps S41, S42, and S43, which specifically include:

[0073] Step S41: Based on the magnetic field superposition constraint, the second calculation result is obtained by using the bearing inner diameter, bearing outer diameter and number of electromagnets;

[0074] Step S42: Calculate the product of the effective coverage radius and the second preset value based on the mechanical interference constraint to obtain the third calculation result;

[0075] Step S43: Determine the minimum value from the second calculation result and the third calculation result, and use it as the electromagnet spacing.

[0076] In this step, the specific process for determining the spacing between the electromagnets is as follows:

[0077]

[0078] In the above formula, The spacing between adjacent electromagnets is the continuous coverage distance of the magnetic field, ensuring that the magnetic fields of adjacent electromagnets are continuously superimposed in the circumferential direction; R eff The effective radius of the bearing. 0.9·λ eff This indicates a mechanical safety distance to prevent physical interference between the electromagnet and the steel ball.

[0079] Step S5: Based on the electromagnet geometric data, the number of electromagnets, and the spacing between the electromagnets, construct a spatial arrangement scheme for the electromagnets in the circumferential direction of the target bearing.

[0080] The calculated geometric parameters, quantity, and spacing of the electromagnets are integrated into a specific circumferential arrangement scheme, the installation position of the electromagnets in the bearing is clarified, and design drawings that can guide engineering implementation are formed to achieve the technical goal of actively adsorbing metal debris and suppressing shaft current damage.

[0081] After finalizing the electromagnet arrangement, it is placed within a bearing, which is then mounted on the train traction motor to actively attract metal debris. The electromagnet attraction control model can be divided into manual and automatic modes. In manual mode, the electromagnet is manually activated based on ferrography analysis results. In automatic mode, a preset WPC threshold or large particle percentage (PLP) threshold is used; if these limits are exceeded, the magnetic field is automatically activated for attraction. The electromagnet is only activated when the train is stopped or running at low speed to avoid overheating of the coil due to high-speed rotation. It is understood that WPC represents the wear intensity index, and PLP represents the large particle percentage. Both parameters can be analyzed by observing the morphology, size, composition, and concentration of debris under a microscope to assess the wear condition of the mechanical equipment.

[0082] 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, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, 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, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0083] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" 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 direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0084] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0085] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A design method for an electromagnetically cleaned and lubricated bearing for a traction motor, comprising: The bearing includes an outer ring (1), an inner ring (2) and at least two steel balls (3), the steel balls (3) being disposed between the outer ring (1) and the inner ring (2), the space between the inner ring (2) and the outer ring (1) being filled with grease (4), and the steel balls (3) contacting the inner ring (2) and the outer ring (1) respectively; Electromagnet (5), at least two electromagnets (5) are provided, the electromagnets (5) are evenly distributed along the circumference of the bearing, the electromagnets (5) are provided between two adjacent steel balls (3), and the magnetic field generated by the electromagnets (5) is in the same direction as the circumference of the bearing. The design method for the electromagnetic purification and lubrication bearing used in the traction motor includes the following steps: Obtain the bearing's geometric parameters, preset magnetic field strength constraints, and temperature rise constraints; The geometric parameters of the electromagnet are calculated under the preset magnetic field strength constraint and temperature rise constraint, and the calculation results are obtained, including the diameter of the electromagnet. The number of electromagnets is determined based on the geometric parameters of the bearing and the diameter of the electromagnet. Based on the constraints of magnetic field superposition and mechanical interference, the minimum layout spacing between adjacent electromagnets is calculated, and the electromagnet spacing is obtained. Based on the electromagnet's geometric parameters, the number of electromagnets, and the spacing between them, a spatial arrangement scheme for the electromagnets in the bearing's circumferential direction is constructed. The calculation of the electromagnet's geometric parameters under the preset magnetic field strength and temperature rise constraints includes: Obtain the vacuum permeability, the relative permeability of the core material, the target magnetic field strength, the core length, and the operating current; The number of coil turns is calculated based on the vacuum permeability, the relative permeability of the core material, the target magnetic field strength, the core length, and the operating current. Obtain the saturation magnetic flux density of the magnetic core and the length of the magnetic circuit; Calculate the cross-sectional area of ​​the magnetic core based on the core saturation magnetic flux density, magnetic circuit length, and number of coil turns. The diameter of the electromagnet is calculated based on the cross-sectional area of ​​the magnetic core. The determination of the number of electromagnets based on the bearing's geometric parameters and the electromagnet diameter included in the calculation results includes: The bearing inner diameter, outer diameter, number of steel balls, and diameter of steel balls are determined based on the bearing's geometric parameters, and the effective magnetic field coverage perimeter is calculated. The effective coverage radius of a single electromagnet is obtained by multiplying the first preset value by the diameter of the electromagnet. The first calculation result is obtained by multiplying the preset safety margin coefficient with the effective magnetic field coverage perimeter. The number of electromagnets is obtained by calculating the ratio of the first calculation result to the effective coverage radius; Among them, the minimum arrangement spacing between adjacent electromagnets is calculated based on magnetic field superposition constraints and mechanical interference constraints, including: Based on the magnetic field superposition constraint, the second calculation result is obtained by calculating the bearing inner diameter, bearing outer diameter and number of electromagnets; The third calculation result is obtained by multiplying the effective coverage radius by the second preset value based on the mechanical interference constraint. The minimum value is determined from the second and third calculation results and used as the electromagnet spacing.

2. The design method for an electromagnetically purified lubricated bearing for a traction motor according to claim 1, characterized in that, Obtaining the length of the magnetic circuit includes: Based on the geometric parameters of the bearing, determine the model information of the electromagnet suitable for installation on the inner and outer rings of the bearing; Based on the electromagnet model information, the corresponding outer diameter and inner diameter of the magnetic core are determined; The magnetic circuit length is calculated based on the outer diameter and inner diameter of the magnetic core.

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