Electrically conductive bearing for driving a motor

Abstract

A kind of electrically conductive bearing for driving motor, including bearing body, the bearing body includes bearing inner ring, bearing ball, bearing outer ring, the bearing ball is arranged between bearing inner ring and bearing outer ring, annular electrically conductive composite carbon fiber is equipped between the bearing inner ring, bearing outer ring, the electrically conductive composite carbon fiber is set to two, respectively located at the two sides of bearing ball, the electrically conductive composite carbon fiber is three-layer structure wrapped together, wherein innermost layer is glass fiber, middle layer is carbon fiber felt wrapped on glass fiber, outermost layer is electrically conductive carbon fiber wrapped on carbon fiber felt, one end of the electrically conductive composite carbon fiber is fixedly connected with bearing inner ring, and the other end is in abutment with the inner ring surface of bearing outer ring.

Description

Technical Field

[0001] This utility model relates to the field of bearings, specifically to a conductive bearing for drive motors, which is particularly suitable for electric vehicle drive motors operating under high voltage and high speed conditions. Background Technology

[0002] As the core power component of electric vehicles, the reliability of the bearings in the drive motor directly determines the motor's lifespan and the vehicle's safety. In existing drive motor systems, the core problem facing bearings is persistent electro-corrosion. Because motors often use inverters for power supply, the high-frequency voltage pulses in the input signal create distributed capacitance in various parts of the motor, generating high-frequency circulating currents. This current forms a loop along the shaft, the bearings at both ends, and the motor housing. As precision components, bearings are easily damaged by this shaft current, which can break down the oil film between the rolling elements and the inner and outer rings. This results in uneven electro-corrosion pits on the contact surface, leading to increased motor noise, abnormal bearing heating, and in severe cases, direct bearing damage. Statistics show that this type of electro-corrosion accounts for more than 65% of electric vehicle drive motor bearing failures.

[0003] In the prior art, the following solutions are proposed to address the above problems: 1. Adding a grounding device: This can be achieved by adding a grounding carbon brush to reduce current. However, this structure requires an additional 15-20mm of axial space in the motor, directly leading to a decrease in motor power density. At the same time, the carbon brush generates dust during operation, polluting the system environment, and is subject to natural wear, requiring regular disassembly and maintenance, increasing operating costs. Another option is to add a metal guide ring structure to reduce current. However, under high-speed vibration conditions, the poor hardness matching between the metal guide ring and the bearing components leads to accelerated wear of the bearing components, which not only shortens the bearing's service life but may also generate metal debris, causing internal motor failures.

[0004] 2. Use of composite conductive materials: In the existing technology, the single-layer carbon fiber conductive structure (such as patent US20210082622A1) has insufficient impact resistance and is prone to interlayer delamination under high speed conditions (>15000rpm), losing its conductive function; while the conductivity of the resin-based composite conductive material is extremely sensitive to temperature, and the conductivity fluctuates significantly with temperature. When the temperature is >100℃, the resistance value can increase by 300%, which cannot adapt to the temperature fluctuations during the operation of the drive motor, resulting in poor conductivity stability and difficulty in long-term reliable operation.

[0005] The utility model patent CN219975156U, entitled "A Conductive Bearing," provides a conductive bearing that uses a conductive sleeve fixed to the inner ring of the bearing, and conductive fibers fixed to the conductive sleeve, so that the conductive fibers contact the inner surface of the outer ring of the bearing. However, in actual use, when an oil film is present on the bearing, the conductive fibers need to scrape off the oil film before conductivity can be achieved. Furthermore, under certain vibration conditions, the conductive fibers may not make contact with the outer ring of the bearing, resulting in a lack of conductivity. In addition, its impact resistance is insufficient, and it is prone to interlayer delamination under high-speed conditions, losing its conductivity.

[0006] Therefore, there is an urgent need for a conductive bearing structure that can achieve high-efficiency conductivity, impact resistance, and temperature resistance within a compact space. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a conductive bearing for a drive motor. It achieves high-efficiency conductivity and strong impact resistance by setting an annular conductive composite carbon fiber between the inner and outer rings of the bearing, ensuring that the conductive composite carbon fiber is in constant contact with the outer ring of the bearing.

[0008] The technical solution of this utility model is as follows: a conductive bearing for a drive motor, comprising a bearing body, the bearing body including an inner bearing ring, bearing balls, and an outer bearing ring, the bearing balls being disposed between the inner and outer bearing rings, and an annular conductive composite carbon fiber being disposed between the inner and outer bearing rings, two of which are respectively located on both sides of the bearing balls, the conductive composite carbon fiber having a three-layer structure wrapped together, wherein the innermost layer is glass fiber, the middle layer is carbon fiber stacked fabric wrapped on glass fiber, and the outermost layer is conductive carbon fiber wrapped on carbon fiber stacked fabric, one end of the conductive composite carbon fiber being fixedly connected to the inner bearing ring, and the other end abutting against the inner ring surface of the outer bearing ring.

[0009] Preferably, the conductive carbon fiber is woven from T800 grade conductive carbon fiber bundles.

[0010] Preferably, the carbon fiber stacked fabric is a twill carbon fiber fabric, and the porosity of the carbon fiber stacked fabric is 50% to 70%.

[0011] Preferably, the glass fiber is 15 wt% glass fiber, and the glass fiber is impregnated with epoxy resin.

[0012] Preferably, the conductive composite carbon fiber is hot-pressed into an interference fit with the inner ring of the bearing.

[0013] Preferably, the surface roughness Ra of the inner ring surface of the bearing outer ring is ≤0.2 μm.

[0014] The beneficial effects of this utility model are as follows: 1. This utility model achieves conductivity by using a three-layer conductive composite carbon fiber structure, with the resistivity of the outermost conductive carbon fiber layer ≤ 5× Ω•m ensures low-resistance contact, provides a flexible and high-strength conductive path, and achieves efficient conductivity. The carbon fiber stacked fabric in the middle layer forms an energy absorption network, which can absorb high-frequency vibration energy under vibration conditions and improve overall stability. The innermost glass fiber enhances its fracture resistance and improves its impact resistance through fiber cross-linking.

[0015] 2. One end of the conductive composite carbon fiber of this utility model is fixed to the inner ring of the bearing by interference fit after hot pressing, and the other end abuts against the outer ring of the bearing, ensuring that the inner ring and the outer ring of the bearing are always connected by the conductive composite carbon fiber, so as to achieve conductivity and avoid conductivity failure due to the presence of oil film. At the same time, it avoids the separation of the conductive composite carbon fiber from the outer ring of the bearing due to vibration conditions. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 for Figure 1 AA section view; Figure 3 for Figure 2 Enlarged view of point B. Detailed Implementation

[0017] See Figures 1 to 3A conductive bearing for a drive motor includes a bearing body 1, which comprises an inner bearing ring 11, bearing balls 12, and an outer bearing ring 13. The bearing balls 12 are disposed between the inner bearing ring 11 and the outer bearing ring 13. An annular conductive composite carbon fiber 14 is disposed between the inner bearing ring 11 and the outer bearing ring 13. By disposing of the annular conductive composite carbon fiber 14, the conductive composite carbon fiber 14 is in surface contact with both the inner bearing ring 11 and the outer bearing ring 13, thereby increasing the contact area of ​​the current path. Two conductive composite carbon fibers 14 are disposed on both sides of the bearing balls 12. The conductive composite carbon fiber 14 has a three-layer structure wrapped together, wherein the innermost layer is glass fiber 143, which is 15wt% glass fiber. The glass fiber 143 is impregnated and cured with epoxy resin, and the glass fiber 143 enhances its fracture resistance and impact resistance through fiber cross-linking. The middle layer is a carbon fiber stacked fabric 142 wrapped around glass fiber 143. The carbon fiber stacked fabric 142 is a twill carbon fiber cloth with a porosity of 50%–70%, preferably 60% in this example. This carbon fiber stacked fabric forms an energy absorption network, capable of absorbing high-frequency vibration energy under vibration conditions, thus improving overall stability. The outermost layer is a conductive carbon fiber 141 wrapped around the carbon fiber stacked fabric 142. The conductive carbon fiber 141 is woven from T800 grade conductive carbon fiber bundles with a resistivity ≤5× The Ω•m value ensures low-resistance contact, providing a flexible and high-strength conductive path for efficient conductivity. One end of the conductive composite carbon fiber 14 is hot-pressed to the inner ring 11 of the bearing and then fixedly connected by an interference fit of 0.02–0.05 mm to ensure the stability of the connection between the conductive composite carbon fiber 14 and the inner ring 11, preventing separation. The other end abuts against the inner ring surface of the outer ring 13 of the bearing. This contact between the conductive composite carbon fiber 14 at this end and the inner ring surface of the outer ring 13 allows for a certain degree of elastic deformation at the end of the conductive composite carbon fiber 14, ensuring constant contact between the conductive fiber and the outer ring of the bearing even under vibration conditions, thus achieving conductivity. The surface roughness Ra of the inner ring surface of the bearing outer ring 13 is ≤0.2μm. The inner ring surface of the bearing outer ring 13 is ground with diamond. The recommended process parameters are: grinding pressure: 0.3MPa, linear speed: 15m / s, so that the final roughness Ra=0.18μm. By reducing the surface roughness of the inner ring surface of the bearing outer ring 13, the friction between the conductive composite carbon fiber 14 and the bearing outer ring 13 is reduced.

[0018] In this embodiment, the three-layer structure of the conductive composite carbon fiber 14 is manufactured by compression molding. The measured current carrying capacity of the conductive bearing of this invention is increased to approximately 50A.

[0019] Finally, it should be noted that the above-described embodiments are merely preferred embodiments of this patent used to illustrate the technical solution of this utility model, and are not intended to limit it, much less limit the scope of protection of this patent; although the patent has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of protection of the claims.

Claims

1. A conductive bearing for a drive motor, comprising a bearing body (1), the bearing body (1) comprising an inner bearing ring (11), bearing balls (12), and an outer bearing ring (13), the bearing balls (12) being disposed between the inner bearing ring (11) and the outer bearing ring (13), characterized in that: A ring-shaped conductive composite carbon fiber (14) is provided between the inner ring (11) and the outer ring (13) of the bearing. Two conductive composite carbon fibers (14) are provided, located on both sides of the bearing ball (12). The conductive composite carbon fiber (14) is a three-layer structure wrapped together. The innermost layer is glass fiber (143), the middle layer is carbon fiber stacked fabric (142) wrapped on glass fiber (143), and the outermost layer is conductive carbon fiber (141) wrapped on carbon fiber stacked fabric (142). One end of the conductive composite carbon fiber (14) is fixedly connected to the inner ring (11) of the bearing, and the other end abuts against the inner ring surface of the outer ring (13) of the bearing.

2. The conductive bearing for a drive motor according to claim 1, characterized in that: The conductive carbon fiber (141) is woven from T800 grade conductive carbon fiber bundles.

3. The conductive bearing for a drive motor according to claim 1, characterized in that: The carbon fiber stacked fabric (142) is a twill carbon fiber fabric, and the porosity of the carbon fiber stacked fabric (142) is 50% to 70%.

4. The conductive bearing for a drive motor according to claim 1, characterized in that: The glass fiber (143) is 15 wt% glass fiber, and the glass fiber (143) is impregnated with epoxy resin.

5. The conductive bearing for a drive motor according to claim 1, characterized in that: The conductive composite carbon fiber (14) is hot-pressed into an interference fit with the inner ring (11) of the bearing.

6. The conductive bearing for a drive motor according to claim 1, characterized in that: The surface roughness Ra of the inner ring surface of the outer ring (13) of the bearing is ≤0.2μm.

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