Motor and vehicle

Abstract

The invention relates to the technical field of vehicles, particularly provides a motor and a vehicle, and aims to solve the problem that the performance of an existing conductive brush is easily affected by oil stains due to the fact that the conductive brush is arranged at a driving end. Therefore, the motor comprises a shell, a driving end bearing, a non-driving end bearing, a driving shaft and a conductive brush device, the two ends of the driving shaft are rotationally connected with the shell through the driving end bearing and the non-driving end bearing respectively, and the conductive brush device is arranged on one side of the non-driving end bearing and electrically makes contact with the driving shaft. The conductive brush device is arranged at the non-driving end of the motor, the environment of the non-driving end is clean, the pollution of gear oil can be isolated, the conductive brush device can always keep direct and low-resistance contact between metals, a shaft voltage discharge channel is ensured to be always unobstructed, and the non-driving end is usually easy to approach; maintenance personnel can directly contact with the conductive brush device without dismounting any large peripheral equipment, and the conductive brush device is convenient to replace.

Description

Technical Field

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

[0002] In motor drive systems, the common-mode voltage generated by the high-frequency switching operation of the inverter is coupled to the motor rotor through parasitic capacitance, forming a rotor shaft voltage to ground. When this voltage exceeds the insulation breakdown threshold of the bearing lubricating grease, it will cause electrical spark discharge in the oil film between the bearing balls and raceways, resulting in electro-corrosion damage. Over time, defects such as pits and etching streaks appear on the bearing raceway surface, leading to increased vibration and noise, and reducing system reliability and service life.

[0003] To suppress shaft voltage and bearing current, rotor shaft grounding devices are commonly used in engineering. These devices form a low-impedance path by contacting the motor drive shaft with conductive brushes, discharging the shaft voltage to ground and thus preventing oil film breakdown and discharge corrosion. This type of method can alleviate electro-corrosion problems to a certain extent and is characterized by its simple structure and low cost.

[0004] However, existing shaft grounding devices often place the conductive brush at the motor drive end, which has significant limitations. Specifically, the drive end is close to the gearbox and is susceptible to gear oil seepage and contamination. Oil stains adhering to the brush surface can increase contact resistance, weaken conductivity, reduce leakage effect, or even cause complete failure.

[0005] Therefore, a new technical solution is needed in this field to solve the above problems. Summary of the Invention

[0006] The present invention aims to solve the above-mentioned technical problems, namely, to solve the problem that the performance of the conductive brushes of existing motors is easily affected by oil stains because they are arranged at the drive end of the motor.

[0007] In a first aspect, the present invention provides an electric motor, including a housing, a drive end bearing, a non-drive end bearing, a drive shaft, and a conductive brush device. The two ends of the drive shaft are rotatably connected to the housing via the drive end bearing and the non-drive end bearing, respectively. The conductive brush device is disposed on the side of the non-drive end bearing away from the drive end bearing and is in electrical contact with the drive shaft.

[0008] In the preferred embodiment of the above motor, the impedance value of the conductive brush device is R, R < T0 / (N×C); where N is the voltage discharge safety constant; T0 is the preset shaft-to-ground voltage discharge time; and C is the equivalent capacitance between the drive shaft and the housing.

[0009] In the preferred embodiment of the above motor, the non-drive end bearing is an insulated bearing, and R > Vs / I0; where Vs is the differential mode shaft voltage induced at both ends of the drive shaft; and I0 is the maximum allowable shaft circulating current.

[0010] In the preferred embodiment of the above-mentioned motor, the conductive brush device includes a conductive brush bundle and a brush holder. One end of the conductive brush bundle is in sliding contact with the drive shaft, and the other end of the conductive brush bundle is electrically connected to the housing through the brush holder.

[0011] In the preferred embodiment of the above-mentioned motor, a mounting groove is provided on the housing, and the brush holder is fixedly installed in the mounting groove, or

[0012] A bracket is mounted on the housing, and the brush holder is fixed on the bracket. The brush holder is electrically connected to the housing through the bracket.

[0013] In the preferred embodiment of the above-mentioned motor, the conductive brush bundle is made of a composite material containing polytetrafluoroethylene and conductive filler.

[0014] In the preferred embodiment of the above-mentioned motor, the motor further includes a gearbox, the input shaft of which is connected to the drive shaft on one side of the drive end bearing.

[0015] In the preferred embodiment of the above-mentioned motor, the non-driving end bearing is a ceramic bearing or a hybrid ceramic bearing using ceramic rolling elements.

[0016] In the preferred embodiment of the above-mentioned motor, the non-driving end bearing is a bearing treated with an insulating coating, the insulating coating covering at least one surface of the inner ring, outer ring, or rolling elements of the bearing.

[0017] In a second aspect, the present invention provides a vehicle comprising the motor described in any of the preceding claims.

[0018] Those skilled in the art will understand that the technical solution of the present invention provides a motor, including a housing, a drive-end bearing, a non-drive-end bearing, a drive shaft, and a conductive brush device. Both ends of the drive shaft are rotatably connected to the housing via the drive-end bearing and the non-drive-end bearing, respectively. The conductive brush device is disposed on the side of the non-drive-end bearing away from the drive bearing and is in electrical contact with the drive shaft. By adopting the above technical solution, the present invention can effectively solve the problem that existing conductive brushes, due to their placement at the drive end, are easily affected by oil contamination, thus impacting performance. Specifically, by placing the conductive brush device at the non-drive end of the motor, the clean environment at the non-drive end isolates it from gear oil contamination. The conductive brush device can always maintain direct, low-resistance metal-to-metal contact, ensuring that the shaft voltage discharge channel remains unobstructed. Furthermore, the non-drive end is typically easily accessible, allowing maintenance personnel to directly access the conductive brush device without disassembling any large peripheral equipment, facilitating replacement of the conductive brush device.

[0019] Furthermore, the impedance value of the conductive brush device of the present invention is R, R < T0 / (N×C); where N is a constant; T0 is the preset shaft-to-ground voltage discharge time; and C is the equivalent capacitance between the drive shaft and the housing. This setting allows the current to be automatically discharged through the conductive brush without passing through the highly insulating bearing oil film, thereby protecting the bearing from electro-corrosion.

[0020] Furthermore, the non-drive end bearing of this invention is an insulated bearing, and R > Vs / I0; where Vs is the differential mode shaft voltage induced at both ends of the drive shaft; and I0 is the maximum permissible shaft circulating current. This setting actively limits the magnitude of the circulating current within a safe range. This ensures that the circulating current is always less than the bearing's safe current threshold, avoiding the risk of accidental damage to the drive end bearing due to differential mode voltage discharge. Attached Figure Description

[0021] The preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which:

[0022] Figure 1 This is a schematic diagram of the motor structure of the present invention;

[0023] Figure 2 This is a schematic diagram of the differential mode shaft voltage and circulating current in the motor of the present invention;

[0024] Figure 3 This is a discharge schematic diagram of the conductive brush device of the present invention;

[0025] Figure 4 This is a schematic diagram of the guide brush device of the present invention suppressing shaft circulating current;

[0026] Figure 5 This is a schematic diagram of the conductive brush device of the present invention.

[0027] List of reference numerals in the attached diagram:

[0028] 1. Housing; 2. Drive end bearing; 3. Non-drive end bearing; 4. Drive shaft; 5. Conductive brush assembly; 51. Conductive brush bundle; 52. Brush holder. Detailed Implementation

[0029] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. For example, although the following embodiments are described in conjunction with an electric motor, the conductive brush device in the electric motor provided by the present invention is also applicable to other products that need to solve the problems of conductive brushes being easily affected by oil contamination due to their location at the drive end and the inconvenience of replacement.

[0030] It should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly, for example, they can refer to a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0031] The motor drive end is typically directly connected to power output mechanisms such as gearboxes and transmissions, forming a closed or semi-closed cavity. During high-speed gear meshing, oil mist and splashed lubricating oil are generated, which inevitably seeps into and adheres to the adjacent conductive brush assembly. Lubricating oil itself is an insulator. When the surface of the conductive brush bristles is covered with oil, an insulating film forms between it and the motor shaft, significantly increasing the contact resistance. According to Ohm's law (V=IR), with a constant shaft voltage (V), an increase in resistance (R) will lead to a sharp decrease in the discharge current (I). Ultimately, the conductive brush loses its discharge function, and the shaft voltage will still break down the bearing oil film, causing galvanic corrosion of the bearing.

[0032] Furthermore, the drive end space is usually tightly surrounded by peripheral equipment such as gearboxes, couplings, and cooling fans. The installation location of the conductive brush is often very concealed and in a confined space. Replacing a low-value conductive brush may require a series of complex pre-processing operations, such as disassembling the cooling fan, removing the coupling cover, and even separating the entire motor from the gearbox, which is time-consuming and labor-intensive.

[0033] To address the aforementioned problems, this invention provides a motor designed to effectively solve the issues of existing conductive brushes being susceptible to performance degradation due to oil contamination and inconvenient replacement by placing the conductive brush device at the non-drive end.

[0034] like Figure 1As shown, the present invention provides an electric motor, including a housing 1, a drive end bearing 2, a non-drive end bearing 3, a drive shaft 4, and a conductive brush device 5. The two ends of the drive shaft 4 are rotatably connected to the housing 1 through the drive end bearing 2 and the non-drive end bearing 3, respectively. The conductive brush device 5 is disposed on the side of the non-drive end bearing 3 away from the drive end bearing 2 and is in electrical contact with the drive shaft 4.

[0035] The housing 1 is the main structure of the motor and also serves to protect the internal structure; the drive shaft 4 is the rotating output shaft of the motor; the drive end bearing 2 is located at the drive end of the motor and is responsible for bearing the main working load (such as radial force and axial force); the non-drive end bearing 3 is located at the non-drive end of the motor and mainly serves to support and position it.

[0036] The present invention mounts and fixes the conductive brush device 5 on the housing 1 on the side of the non-drive end bearing 3, and ensures that it maintains stable and reliable electrical contact with the surface of the high-speed rotating drive shaft 4.

[0037] After the shaft voltage is generated inside the motor, it appears on the entire drive shaft 4. Without the conductive brush device 5, a strong shaft voltage will form on the drive-end bearing 2 or the non-drive-end bearing 3, which can easily cause the oil film in the drive-end bearing 2 or the non-drive-end bearing 3 to break down and generate electrical sparks. This invention establishes a low-impedance electrical path after the conductive brush device 5 contacts the drive shaft 4 at the non-drive end. The shaft voltage is then safely discharged to the ground via the conductive brush device 5 and the housing 1, thereby preventing voltage accumulation on the drive-end bearing 2 or the non-drive-end bearing 3 and fundamentally preventing the breakdown of the bearing oil film and electrical sparks.

[0038] Furthermore, by placing the conductive brush device 5 at the non-drive end of the motor, the present invention completely eliminates the possibility of gear oil contamination due to the clean environment at the non-drive end. The conductive brush device 5 can always maintain direct, low-resistance contact between metals, ensuring that the shaft voltage discharge channel is always unobstructed.

[0039] By avoiding factors that cause performance degradation, the discharge effect of the conductive brush device 5 remains stable throughout its entire life cycle, greatly extending the service life of the bearings and the motor itself, and improving the reliability of the entire drive system.

[0040] Furthermore, the non-drive end is typically easily accessible, allowing maintenance personnel to directly access the conductive brush assembly 5 without disassembling any large peripheral equipment. Replacement operations may take only a few minutes, similar to replacing a simple sensor.

[0041] Preferably, the impedance value of the conductive brush device 5 is R, R < T0 / (N×C); where N is the voltage discharge safety constant; T0 is the preset shaft-to-ground voltage discharge time; and C is the equivalent capacitance between the drive shaft 4 and the housing 1.

[0042] Figure 3 Shows the discharge schematic diagram of the conductive brush device of the present invention. It should be noted that the impedance value R (unit: ohm) of the conductive brush device 5 includes the resistance of the conductive brush device 5 itself, the contact resistance between the conductive brush device 5 and the drive shaft 4, and the resistance of any terminal.

[0043] The equivalent capacitance C (unit: farad) between the drive shaft 4 and the housing 1 is determined by the internal structure of the motor (such as windings, bearings, air gap), especially the distributed capacitance between the rotor (drive shaft 4) and the stator. For a specific motor, this value can be regarded as a relatively fixed parasitic parameter.

[0044] The preset shaft voltage discharge time T0 (unit: second) is an engineering target value. It means that when a peak shaft voltage appears, the system requires how short a time it must discharge it below the safety threshold (to avoid breaking through the bearing oil film). The smaller the T0 value, the faster the required discharge speed and the safer the system.

[0045] The voltage discharge safety constant N is a constant related to the completion degree of the discharge target, and it comes from the mathematical equation of the RC circuit discharge. For example, if it is required that the voltage decays to 1% of the initial value within the time T0 (that is, 99% of the voltage is discharged), then the value of N is about 4.6 (because e^(-T0 / RC) = 0.01, and solving gives T0 / RC ≈ 4.6, that is, R < T0 / (4.6C). The specific value of N depends on the designed safety margin, and the present invention does not limit the specific value of N here.

[0046] Furthermore, it should be noted that the shaft voltage problem in the motor system is essentially a capacitor charge and discharge problem. The drive shaft 4 (rotor) and the stator / housing 1 are coupled through the parasitic capacitance C. The high-frequency switching action of the inverter is equivalent to a continuous charging power source, continuously charging this capacitor, resulting in the increase of the shaft voltage. When this voltage exceeds the insulation strength of the bearing lubricating grease, it will generate an electric spark discharge through the oil film between the bearing balls and the raceway, and long-term action will cause electrical corrosion damage such as pits and grooves on the bearing raceway.

[0047] To protect the bearing, a discharge circuit with a lower impedance than the "breaking through the bearing oil film" path must be provided. The present invention arranges the conductive brush device 5 on one side of the non-drive end bearing 3. Since the conductive brush device 5 is electrically connected to the non-drive end bearing 3 and the housing 1, thus, a current path will be formed in the motor: drive shaft 4 → drive end bearing 2 → housing 1 → conductive brush device 5 → non-drive end bearing 3 (as Figure 2 shown).

[0048] Based on the principle that current always tends to flow along the path of lowest impedance, the present invention designs the impedance value R of the conductive brush device 5 to be less than T0 / (N×C), so that the vast majority of current automatically chooses to be discharged through the "shortcut" of conductive brush-housing 1, and almost no current "takes a detour" to forcibly pass through the highly insulating bearing oil film, thereby avoiding the breakdown of the bearing oil film and generating electric spark discharge, thus protecting the bearing from electro-corrosion.

[0049] Furthermore, the conductive brush device 5 installed on the non-drive end avoids oil contamination, and its contact resistance R value remains stable and low throughout its entire lifespan. This eliminates the intermittent protection problem caused by oil contamination, ensuring continuous and reliable protection that does not degrade throughout the entire motor lifespan and effectively preventing chronic electro-corrosion.

[0050] Preferably, the non-driving end bearing 3 is an insulated bearing, and the impedance value R of the conductive brush device 5 is greater than Vs / I0; where Vs is the differential mode shaft voltage induced at both ends of the drive shaft 4; and I0 is the maximum allowable shaft circulating current.

[0051] Figure 4 A schematic diagram of the guide brush device of the present invention suppressing shaft circulating current is shown. It should be noted that, in addition to the shaft-to-ground voltage causing bearing oil film breakdown and discharge, the magnetic field of the motor also induces differential-mode shaft voltage (such as...) at both ends of the drive shaft 4 during operation. Figure 2 As shown, if both the drive end and the non-drive end bearings of drive shaft 4 are ordinary bearings, the differential voltage Vs will form a closed loop between drive shaft 4, the bearings at both ends, and the housing. The impedance of this loop is mainly the oil film impedance of the two bearings. If the current is large enough, it will damage both bearings at the same time.

[0052] This invention sets the non-drive end bearing 3 as an insulating bearing, physically cutting off the default path of the aforementioned circulating current. Current can no longer pass through the non-drive end bearing 3, thus protecting it.

[0053] However, even after disconnecting the aforementioned circuit, the differential voltage Vs still exists, and it must find a path to discharge. Since the present invention places the conductive brush device 5 on the non-drive end bearing 3 side, the conductive brush device 5 is electrically connected to the non-drive end bearing 3 and the housing 1, forming a closed circuit: drive shaft 4 → drive end bearing 2 → housing 1 → conductive brush device 5 → non-drive end bearing 3 (e.g., ...). Figure 2 As shown in the figure, this loop becomes the only path for the differential voltage Vs to drive the circulating current.

[0054] However, creating a new low-impedance (conductive brush device 5) path introduces a new risk: if the impedance R of this path is too small, according to Ohm's law (I = V / R), the differential-mode voltage Vs will generate a very large circulating current I in this loop. This strong current flowing through the drive-end bearing 2 will also cause severe electro-corrosion.

[0055] To address the issue of excessive circulating current I, this invention sets a lower limit for the impedance R of the conductive brush device 5, namely R > Vs / I0. By designing the impedance R of the conductive brush device 5 to be no less than Vs / I0, the magnitude of the circulating current I can be actively limited within a safe range. This ensures that the circulating current is always less than the bearing's safe current threshold, avoiding the risk of accidental damage to the drive-end bearing 2 due to differential mode voltage discharge.

[0056] Therefore, by setting R to be less than T0 / (N×C), this invention not only ensures rapid discharge of shaft voltage, prevents oil film breakdown, and avoids bearing electro-corrosion, but also ensures that the circulating current is not too large by setting R to be greater than Vs / I0, thereby further preventing current corrosion of the bearing. The drive-end bearing 2 receives double protection (shaft voltage is discharged + differential mode circulating current is limited), minimizing its risk of electro-corrosion. The non-drive-end bearing 3, being inherently insulated, is directly protected from both types of current. This greatly extends the overall lifespan of the bearings at both ends of the motor.

[0057] It should be noted that technicians can select a suitable R value by choosing the material and design of the conductive brush device 5 (such as the resistivity of the conductive brush device 5 material, the pressure of the conductive brush device 5, and the contact area with the drive shaft 4), so that it simultaneously satisfies T0 / (N×C) and Vs / I0.

[0058] It should be further noted that the differential shaft voltage Vs (in volts) induced at both ends of the drive shaft 4 is determined by the electromagnetic design of the motor. The maximum allowable shaft circulating current I0 (in amperes) is a safety threshold, which refers to the maximum current value that will not cause electro-corrosion damage to the drive end bearing 2. This value is determined by the bearing material, grease, operating conditions, etc.

[0059] Preferably, in one embodiment, the non-drive end bearing 3 is a ceramic bearing or a hybrid ceramic bearing using ceramic rolling elements.

[0060] Ceramic materials are excellent electrical insulators with high resistivity, which can effectively block the conduction of current, prevent current from forming a circuit through the bearing, avoid electro-corrosion, protect the bearing, and improve the service life and reliability of the motor.

[0061] In addition, ceramic bearings or hybrid ceramic bearings have advantages such as wear resistance, corrosion resistance, and long service life, which reduces the frequency of bearing replacement and maintenance, lowers the maintenance cost and downtime of the motor, and improves the economic efficiency of motor use.

[0062] Preferably, in another embodiment, the non-drive end bearing 3 is a bearing treated with an insulating coating, which covers at least one surface of the bearing's inner ring, outer ring, or rolling elements. The insulating coating maintains relatively stable electrical resistance under varying temperature, humidity, and chemical conditions. Even under harsh operating conditions, it continues to provide insulation, ensuring the long-term reliable operation of the non-drive end bearing 3.

[0063] Preferably, the motor further includes a gearbox (not shown in the figure), the input shaft of which is connected to the drive shaft 4 on one side of the drive end bearing 2.

[0064] It should be noted that drive shaft 4 and gearbox input shaft are essentially connected as a continuous conductor. The shaft voltage and differential mode voltage generated on drive shaft 4 will be transmitted unimpeded to the gearbox input shaft through this connection. The gearbox also has bearings (usually rolling or sliding bearings) to support its input, intermediate, and output shafts. These bearings also have an insulating lubricating oil film between their raceways and balls. Therefore, the shaft voltage finds a new discharge path: gearbox input shaft → gearbox input shaft bearing → gearbox housing 1 → ground. When the voltage here exceeds the breakdown threshold of the gearbox bearing oil film, the same electrical spark discharge and electro-corrosion problems will occur inside the gearbox bearings.

[0065] By placing the conductive brush device 5 on the non-drive shaft 4 bearing side, the present invention ensures that the shaft voltage generated inside the motor or gearbox will preferentially be discharged through the conductive brush device 5 on the non-drive end of the motor. Therefore, the voltage difference between the two ends of the gearbox input shaft bearing is maintained at an extremely low level, never reaching the breakdown threshold of its oil film, thereby eliminating the risk of electro-corrosion of the gearbox bearing.

[0066] Preferably, such as Figure 5 As shown, the conductive brush device 5 includes a conductive brush bundle 51 and a brush holder 52. One end of the conductive brush bundle 51 is in sliding contact with the drive shaft 4, and the other end is electrically connected to the housing 1 through the brush holder 52.

[0067] The conductive brush bundle 51 is the core component of the conductive brush device 5 that enables current conduction. For example, the conductive brush bundle 51 is typically composed of multiple filaments or sheets made of conductive material. This assembly increases the contact area with the drive shaft 4, improving the stability and reliability of current conduction.

[0068] The brush holder 52 serves to fix the conductive brush bundle 51 and to achieve electrical connection between the conductive brush bundle 51 and the housing 1. For example, the brush holder 52 is made of a material with certain strength and conductivity, which can provide stable support for the conductive brush bundle 51 and ensure that the conductive brush bundle 51 will not shake or shift during operation, thereby ensuring good contact with the drive shaft 4.

[0069] During motor operation, the drive shaft 4 rotates continuously. The conductive brush bundle 51 conducts current from the conductive brush bundle 51 to the drive shaft 4 through sliding friction with the surface of the drive shaft 4. The brush holder 52 guides the current in the conductive brush bundle 51 to the housing 1 through its own conductivity, and then connects it to the motor's electrical circuit.

[0070] Preferably, in one embodiment, the housing 1 has a mounting groove (not shown in the figure), and the brush holder 52 is fixedly installed in the mounting groove.

[0071] The mounting slot provides a clear mounting reference for the brush holder 52, allowing it to be accurately positioned on the housing 1 during installation. This helps ensure the relative positional accuracy between the conductive brush bundle 51 and the drive shaft 4, ensuring good sliding contact between the conductive brush bundle 51 and the drive shaft 4, thereby achieving stable current conduction. If the brush holder 52 is not installed in an accurate position, it may lead to poor contact between the conductive brush bundle 51 and the drive shaft 4, resulting in problems such as electrical sparks and increased contact resistance, affecting the performance and reliability of the motor.

[0072] By fixing the brush holder 52 in the mounting slot, the shaking and displacement of the brush holder 52 during motor operation can be effectively limited. The motor generates vibration and centrifugal force during operation. If the brush holder 52 is not securely installed, it may move under the influence of these forces, affecting the contact between the conductive brush bundle 51 and the drive shaft 4, leading to unstable current conduction. The mounting slot design provides comprehensive constraint on the brush holder 52, ensuring its stability in all directions and guaranteeing that the conductive brush device 5 operates normally throughout the entire service life of the motor.

[0073] In addition, the mounting slot can provide a certain degree of protection for the brush holder 52, preventing it from being impacted or damaged by external objects during motor operation. For example, in some harsh working environments, dust, debris, etc. may enter the motor. The mounting slot can, to some extent, prevent these debris from directly contacting the brush holder 52, reducing the risk of contamination and damage to the brush holder 52.

[0074] Preferably, in another embodiment, a bracket (not shown in the figure) is installed on the housing 1, and the brush holder 52 is fixed on the bracket. The brush holder 52 is electrically connected to the housing 1 through the bracket.

[0075] Using a bracket to mount the brush holder 52 provides greater flexibility in motor design. The bracket can be independently designed and manufactured according to the specific structure, spatial layout, and conductivity requirements of the motor, without being overly restricted by the shape and structure of the housing 1. For example, in some complex motors, the surface of the housing 1 may not have enough suitable space to directly mount the brush holder 52. However, by designing a suitable bracket, the brush holder 52 can be installed in a more ideal position to meet the working requirements of the conductive brush device 5. Furthermore, the mounting method of the bracket can be selected and adjusted according to actual conditions, making the installation of the brush holder 52 more convenient and quick.

[0076] The bracket provides additional support and fixation for the brush holder 52, enhancing the structural stability of the entire conductive brush device 5. During motor operation, the high-speed rotation of the drive shaft 4 generates vibration and centrifugal force. If the brush holder 52 is directly connected to the housing 1, insufficient connection strength may lead to loosening or damage of the brush holder 52. The bracket disperses these forces, securing the brush holder 52 more firmly to the motor, reducing the wobbling and displacement of the brush holder 52 caused by vibration and centrifugal force, ensuring good contact between the conductive brush bundle 51 and the drive shaft 4, and extending the service life of the conductive brush device 5.

[0077] Preferably, the conductive brush bundle 51 is made of a composite material containing polytetrafluoroethylene and conductive filler.

[0078] The low coefficient of friction and non-stick properties of polytetrafluoroethylene (PTFE) result in minimal friction when it slides against the drive shaft 4, reducing wear caused by friction. Simultaneously, its excellent chemical stability makes it less susceptible to corrosion from lubricating oil, impurities, and other substances that may be present on the surface of the drive shaft 4, further reducing the wear rate. This significantly extends the service life of the conductive brush bundle 51, lowering motor maintenance costs and downtime. Furthermore, the low coefficient of friction and non-stick properties ensure the continuity and stability of current transmission, thereby improving the overall reliability and operating efficiency of the motor.

[0079] In addition, the conductive fillers (such as carbon powder, graphite, and metal powder) uniformly dispersed in the polytetrafluoroethylene body form a continuous and stable three-dimensional conductive network, ensuring the effective transmission of current.

[0080] Furthermore, polytetrafluoroethylene (PTFE) can be processed into conductive brush bundles 51 of different shapes and sizes through various processing methods, such as molding, extrusion, and injection molding. This excellent processability allows for precise control of the structural parameters of the conductive brush bundle 51, such as length, width, and thickness, according to the design requirements of the conductive brush device 5. These structural parameters are important factors affecting the impedance of the conductive brush bundle 51. By precisely controlling these parameters, the conductive brush device 5 can more easily meet the design requirements of less than T0 / (N×C) and greater than Vs / I0 simultaneously.

[0081] Furthermore, the present invention provides a vehicle that includes the aforementioned motor.

[0082] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. An electric motor, characterized in that, The device includes a housing (1), a drive end bearing (2), a non-drive end bearing (3), a drive shaft (4), and a conductive brush device (5). The two ends of the drive shaft (4) are rotatably connected to the housing (1) through the drive end bearing (2) and the non-drive end bearing (3), respectively. The conductive brush device (5) is located on the side of the non-drive end bearing (3) away from the drive end bearing (2) and is in electrical contact with the drive shaft (4).

2. The motor according to claim 1, characterized in that, The impedance value of the conductive brush device (5) is R, R < T0 / (N×C); Wherein, N is the voltage discharge safety constant; T0 is the preset shaft-to-ground voltage discharge time; and C is the equivalent capacitance between the drive shaft (4) and the housing (1).

3. The motor according to claim 2, characterized in that, The non-driving end bearing (3) is an insulating bearing, and R > Vs / I0; Wherein, Vs is the differential mode shaft voltage induced at both ends of the drive shaft (4); I0 is the maximum allowable shaft circulating current.

4. The motor according to claim 1, characterized in that, The conductive brush device (5) includes a conductive brush bundle (51) and a brush holder (52). One end of the conductive brush bundle (51) is in sliding contact with the drive shaft (4), and the other end of the conductive brush bundle (51) is electrically connected to the housing (1) through the brush holder (52).

5. The motor according to claim 4, characterized in that, The housing (1) has a mounting groove, and the brush holder (52) is fixedly installed in the mounting groove, or A bracket is installed on the housing (1), and the brush holder (52) is fixed on the bracket. The brush holder (52) is electrically connected to the housing (1) through the bracket.

6. The motor according to claim 4, characterized in that, The conductive brush bundle (51) is made of a composite material containing polytetrafluoroethylene and conductive filler.

7. The motor according to claim 1, characterized in that, The motor also includes a gearbox, the input shaft of which is connected to the drive shaft (4) on one side of the drive end bearing (2).

8. The motor according to claim 3, characterized in that, The non-driving end bearing (3) is a ceramic bearing or a hybrid ceramic bearing with ceramic rolling elements.

9. The motor according to claim 3, characterized in that, The non-driving end bearing (3) is a bearing treated with an insulating coating, which covers at least one surface of the bearing’s inner ring, outer ring, or rolling elements.

10. A vehicle, characterized in that, The motor included in any one of claims 1 to 9.

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