Motor capable of preventing electric corrosion of bearing

Abstract

The utility model discloses a motor capable of preventing electrocorrosion of a bearing, which comprises a rotating shaft, a front end cover, a casing, a rear end cover and a cover plate, the front end cover and the rear end cover are positioned on two sides of the casing, and the rotating shaft penetrates through the front end cover and the rear end cover; a conducting ring is arranged on the rear end cover, the rotating shaft is sleeved with the conducting ring, a conducting ring fiber bundle is arranged on the conducting ring, and the conducting ring fiber bundle makes contact with the rotating shaft; a cover plate is arranged on the rear end cover and seals the conducting ring, the conducting ring fiber bundle and the end part of the rotating shaft; ceramic insulating coatings are arranged between the front bearing and the rotating shaft and between the rear bearing and the rotating shaft. The insulating coating is additionally arranged at the position of the bearing retainer of the rotating shaft, the rotating shaft and the bearing inner ring are insulated and isolated, impedance of a closed frame loop is increased, and high-frequency loop current is reduced; the carbon fiber conducting ring is added at one end of the motor to conduct the end cover and the rotating shaft, so that the bearing common-mode voltage is reduced.

Description

Technical Field

[0001] This utility model relates to the field of motor technology, and in particular to a motor that prevents bearing electro-corrosion. Background Technology

[0002] The drive motor is a core component of new energy vehicles, and its operational reliability directly affects the overall vehicle stability. Motor bearings are critical structural components of the drive motor, and their proper functioning is a prerequisite for the motor's normal operation. Under pressure to meet performance and cost demands, electric drive systems are rapidly evolving towards higher voltage, higher speed (high frequency), and higher integration, making motor bearings increasingly susceptible to electro-corrosion. Electro-corrosion continuously damages the drive motor bearings of new energy vehicles, increasing vehicle noise, affecting driving comfort, and even causing bearing seizure, thus impacting vehicle reliability.

[0003] The main causes of electrical corrosion in motor bearings include two aspects:

[0004] (1) In the motor drive system of new energy vehicles, the common mode voltage output by the PWM inverter will be coupled through the high frequency parasitic capacitance inside the motor to generate a bearing common mode voltage at both ends of the bearing. When the bearing voltage exceeds the breakdown threshold voltage of the bearing grease film, the bearing oil film will be discharged and broken down, resulting in the generation of electric spark discharge current, causing corrosion pits on the inner and outer rings and ball surfaces of the bearing.

[0005] (2) A high phase voltage change rate generates a fairly high frequency current, and the current excitation generates an alternating ring magnetic flux, forming a high frequency loop voltage in the closed frame circuit (casing-front cover-front bearing-shaft-rear bearing-rear cover-casing), which in turn generates a high frequency loop current.

[0006] Affected by the above two situations, on the one hand, the bearing grease overheats, carbonizes, and turns black; on the other hand, arc erosion pits and spherical metal particles are formed on the surface of the rolling elements and raceways. Under the interaction of long-term electrical erosion damage and fatigue wear, the damaged parts of the bearing show "washboard pattern" marks, abnormal noise occurs during operation, and even the bearing burns and seizes.

[0007] The four most common solutions to this problem are as follows:

[0008] (1) Use brushes or conductive rings to connect the motor end cover and the shaft. This solution can effectively reduce the bearing common mode voltage, but has little effect on high frequency loop current.

[0009] (2) Add an insulating layer between the end cover and the outer ring of the bearing. This solution protects the bearing on the same side, but cannot protect the bearing on the other side. It cannot reduce the common mode voltage of the bearing. If the motor is connected to a gearbox, the bearing of the gearbox is also at risk of electro-corrosion.

[0010] (3) Adding a resistor-capacitor circuit between the end cap and the shaft results in a complex structure;

[0011] (4) Ceramic ball bearings are used to prevent shaft current from being generated by discharge between the inner and outer rings of the bearing, but ceramic bearings are more expensive.

[0012] Therefore, finding an economical and effective solution to prevent electro-corrosion of motor bearings remains a problem that needs to be solved. Summary of the Invention

[0013] To solve the above problems, this utility model provides a motor that prevents bearing electro-corrosion.

[0014] The technical solution adopted in this utility model is as follows: a motor for preventing bearing electro-corrosion includes a rotating shaft, a front end cover, a housing, a rear end cover, and a cover plate. The front end cover and the rear end cover are located on both sides of the housing, and the rotating shaft passes through the front end cover and the rear end cover. The rotating shaft is rotatably connected to the front end cover and the rear end cover respectively through a front bearing and a rear bearing. A front bearing steel sleeve is provided between the front bearing and the front end cover, and a rear bearing steel sleeve is provided between the rear bearing and the rear end cover. A conductive ring is provided on the rear end cover, and the conductive ring is sleeved outside the rotating shaft. The conductive ring has conductive ring fiber bundles, which are in contact with the rotating shaft. A cover plate is provided on the rear end cover, and the cover plate seals the conductive ring, the conductive ring fiber bundles, and the end of the rotating shaft. A ceramic insulating coating is provided between the front bearing and the rear bearing and the rotating shaft.

[0015] Furthermore, the axial cross-section of the insulating coating is L-shaped, completely separating the front and rear bearings from the shaft.

[0016] Furthermore, the front cover and the rear cover are connected to the controller housing at the same potential via a grounding wire.

[0017] The beneficial effects of this utility model are as follows:

[0018] 1. Add an insulating coating at the contact point between the shaft and the bearing to insulate and isolate the shaft from the inner ring of the bearing, increase the impedance of the closed frame circuit (housing-front cover-front bearing-shaft-rear bearing-rear cover-housing), and reduce high-frequency loop current;

[0019] 2. Add a carbon fiber conductive ring to the rear end cover of the motor to connect the end cover to the shaft, effectively reducing the common mode voltage of the bearing. At the same time, the insulating coating significantly reduces the loop current, thus comprehensively avoiding all factors that cause bearing electro-corrosion. Attached Figure Description

[0020] Figure 1 This is a cross-sectional view of the structure of this utility model;

[0021] Figure 2 This is an enlarged view of the bearing structure of this utility model;

[0022] In the diagram: 101-shaft, 102-front end cover, 103-front bearing steel sleeve, 104-front bearing, 105-machine housing, 106-rear end cover, 107-rear bearing steel sleeve, 108-rear bearing, 109-carbon fiber conductive ring, 110-conductive ring fiber bundle, 111-cover plate, 201-front insulating coating, 202-rear insulating coating. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings.

[0024] like Figure 1 As shown, this utility model is a motor for preventing bearing electro-corrosion, including a rotating shaft 101, a front cover 102, a housing 105, a rear cover 106, and a cover plate 111. The front cover 102 and the rear cover 106 are located on both sides of the housing 105, forming the basic frame of the motor. The front cover 102 and the rear cover 106 are connected to the controller housing at the same potential via a grounding wire. The rotating shaft 101 passes through the front cover 102 and the rear cover 106; the rotating shaft 101 is rotatably connected to the front cover 102 and the rear cover 106 via a front bearing 104 and a rear bearing 108, respectively. Since the motor end covers are generally made of aluminum alloy, and the rotating shaft and bearings are made of steel, to ensure reliability, a front bearing steel sleeve 103 is provided between the front bearing 104 and the front cover 102, and a rear bearing steel sleeve 107 is provided between the rear bearing 108 and the rear cover 106; a carbon fiber conductive ring 109 is provided on the rear cover 106, and the carbon fiber conductive ring 109 is sleeved on the outside of the rotating shaft 101. During operation of the electric drive system, the common-mode voltage across the bearing can be reduced by the carbon fiber conductive ring 109, effectively mitigating the impact of the common-mode voltage on the bearing oil film. The carbon fiber conductive ring 109 is equipped with conductive ring fiber bundles 110, which dynamically rub against the shaft 101 during motor shaft rotation. A cover plate 111 is provided on the rear end cover 106, sealing the carbon fiber conductive ring 109, the conductive ring fiber bundles 110, and the end of the shaft 101. A front insulating coating 201 and a rear insulating coating 202 are provided between the front bearing 104 and the rear bearing 108 and the shaft 101. The insulating coatings are made of ceramic material and are applied to the corresponding positions via plasma spraying to ensure good adhesion between the insulating coating and the shaft.

[0025] like Figure 2 As shown, in order to ensure that the inner ring of the bearing is completely separated from the shaft, the insulating coating in this utility model has an L-shaped structure, so that the two surfaces of the shaft 101 that contact the bearing are separated by the insulating coating.

[0026] When the electric drive system is running, this invention will induce a high-frequency loop current in the annular path of housing 105-front cover 102-front bearing 104-shaft 101-rear bearing 108-rear cover 106-housing 105. By adding a front insulating coating 201 and a rear insulating coating 202 between the shaft 101 and the front bearing 104 and the rear bearing 108 in this annular path, the impedance of the annular path is increased, the high-frequency loop current is significantly reduced, and the bearings are protected.

Claims

1. A motor for preventing bearing electro-corrosion, comprising a rotating shaft, a front end cover, a housing, a rear end cover, and a cover plate, wherein the front end cover and the rear end cover are located on opposite sides of the housing, and the rotating shaft passes through the front end cover and the rear end cover; the rotating shaft is rotatably connected to the front end cover and the rear end cover respectively via a front bearing and a rear bearing; a front bearing steel sleeve is provided between the front bearing and the front end cover, and a rear bearing steel sleeve is provided between the rear bearing and the rear end cover; characterized in that: The rear end cover is provided with a conductive ring, which is sleeved on the outside of the rotating shaft. The conductive ring is provided with a conductive ring fiber bundle, which is in contact with the rotating shaft. The rear end cover is provided with a cover plate, which seals the conductive ring, the conductive ring fiber bundle, and the end of the rotating shaft. The front bearing and the rear bearing are provided with a ceramic insulating coating between themselves and the rotating shaft.

2. The motor for preventing bearing electro-corrosion according to claim 1, characterized in that: The insulating coating has an L-shaped axial section, which completely separates the front and rear bearings from the shaft.

3. The motor for preventing bearing electro-corrosion according to claim 1, characterized in that: The front cover and the rear cover are connected to the controller housing at the same potential via a grounding wire.

Images