Non-contact conductive device for motor rotor

Abstract

The utility model discloses a plurality of non-contact electric conductors for motor rotors. The conductive device is composed of a disc, an annular liquid guide bearing and conductive liquid. The disc is in clearance fit with the annular liquid guide bearing, one or more bidirectional wedge-shaped clearance spaces are formed in the circumferential direction, and the spaces are filled with conductive liquid. When the disc or the annular liquid guide bearing rotates at a high speed along with the rotor of the motor, a conductive lubricating liquid film is formed between the disc and the annular liquid guide bearing by utilizing the wedge-shaped effect of fluid dynamic pressure, and common-mode voltage on the rotor is short-circuited from the disc to the liquid guide bearing and is grounded through a motor shell, so that electrocorrosion failure of the main supporting bearing of the motor is avoided.

Description

Technical Field

[0001] The utility model relates to the field of electromechanical technology, in particular to a non-contact conductor for a motor rotor. Background Art

[0002] In new energy drive motors, due to the imbalance and asymmetry of the motor magnetic circuit and the inability of modern PWM variable frequency power supply voltage source inverters to produce completely symmetrical three-phase waveforms, common mode voltage will be driven on the motor rotor and gradually increase. When the common mode voltage exceeds the limit of the lubricating oil film of the main bearing, it will break through the lubricating oil film and form a circuit. The rolling elements and raceways in the main bearing are in point and line contact, and the contact surface is very small, so a large current density is generated, and frequent discharges produce local high temperatures, causing local melting in the contact area of ​​the main bearing, thereby causing electrical corrosion failure. The current mainstream technologies to solve this problem are mainly divided into insulation and diversion. The insulation measures are mainly to insulate the assembly surface of the main bearing or use hybrid ceramic bearings, but the cost is high and it cannot fundamentally solve the problem. It will cause the common mode charge to be shunted to the low-resistance external connection shaft of the motor, thereby causing the bearing supporting the external connection shaft to fail due to electrical corrosion. The commonly used diversion method is to install conductive devices (such as carbon brushes, conductive rings, etc.) to shunt the common-mode charge on the rotor to the grounded casing. However, this type of device is currently mainly direct contact, which is prone to wear and failure at high speeds, and pollutes the internal environment of the motor, making it difficult to meet the high-speed drive motor requirements of current new energy vehicles.

[0003] The current mainstream technologies to solve this problem are mainly divided into insulation and diversion. The insulation measures mainly involve insulating the assembly surface of the main bearing or using hybrid ceramic bearings, but the cost is high and it cannot fundamentally solve the problem. It will cause the common-mode charge to be shunted to the low-resistance external connection shaft of the motor, thereby causing the bearing supporting the external connection shaft to fail due to electrical corrosion. The diversion method generally uses the installation of conductive devices (such as carbon brushes, conductive rings, etc.) to shunt the common-mode charge on the rotor to the grounded casing, but this type of device is currently mainly direct contact, which is prone to wear and failure at high speeds, and pollutes the internal environment of the motor, making it difficult to meet the current high-speed drive motor requirements of new energy vehicles. Summary of the invention

[0004] In view of the existing technical defects, the utility model provides several non-contact conductors for motor rotors, inspired by the idea of ​​invention patent CN116169835 A. The core principle is to use the fluid dynamic pressure effect generated by the geometric wedges between the disc or annular liquid-conducting bearings when they rotate at high speed to form a conductive liquid film, short-circuit the common mode charge on the rotor to the grounded shell, and avoid wear caused by direct contact of conductive solid materials.

[0005] To achieve the above purpose, the conductor is composed of a disc, an annular liquid-conducting bearing and a conductive liquid. The disc and the annular liquid-conducting bearing are made of metal materials with good conductivity, and the conductive liquid has good conductivity and certain lubricity.

[0006] When the disc is fixed on the outer circle of the motor shaft, the annular liquid-conducting bearing is electromechanically connected to the grounded motor housing; or the annular liquid-conducting bearing is fixed in the inner hole of the motor shaft, and the disc is electromechanically connected to the grounded motor housing. The disc and the annular liquid-conducting bearing are clearance-matched, and the conductive liquid is filled in the clearance space between the disc and the annular liquid-conducting bearing.

[0007] The inner circle of the annular liquid-conducting bearing and the outer circle of the disc can be a complete circle or a multi-oil blade structure, so as to form one or more bidirectional wedge-shaped gaps in the circumferential direction. When the outer circle of the disc and the inner circle of the annular liquid-conducting bearing are both complete circular structures, the disc and the annular liquid-conducting bearing are installed non-concentrically, so as to form a wedge-shaped gap in the circumferential direction.

[0008] At low speed, the conductive liquid establishes radial and axial electrical connections between the disc and the annular liquid-conducting bearing, and short-circuits the common-mode charge on the motor rotor to the grounded housing. At high speed, the rotor drives the disc or the annular liquid-conducting bearing to rotate at high speed, and uses the wedge effect of fluid dynamic pressure to form a conductive liquid film on the wedge-shaped gap between the disc and the annular liquid-conducting bearing, and establishes radial electrical connections between the disc and the annular liquid-conducting bearing, so as to short-circuit the common-mode charge on the motor rotor to the grounded housing.

[0009] The annular liquid-conducting bearing and the disc are provided with dynamic sealing structures on both sides to prevent the conductive liquid from being thrown out during the high-speed rotation of the disc or the annular liquid-conducting bearing. The filling amount of the conductive liquid should be less than half of the wedge-shaped gap space formed by the disc and the annular liquid-conducting bearing.

[0010] The conductor of the utility model realizes non-contact conduction by utilizing a fluid dynamic pressure conductive liquid film, has a simple structure, and can realize effective dynamic conduction in all speed sections (low speed, medium speed, high speed) and in forward and reverse rotation. Its conductivity is much higher than the rolling contact conductivity of the rolling bearing supporting the rotor, and can realize the diversion discharge protection of the main bearing of the high-speed motor rotor. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of a non-contact conductor of a preferred embodiment of an off-axis installation;

[0012] Figure 2 It is a schematic diagram of another preferred embodiment of a non-contact conductor installed in a shaft hole;

[0013] Figure 3 It is a schematic diagram of the combination of discs with different structures and annular liquid-conducting bearings with different structures. DETAILED DESCRIPTION

[0014] In order to make the technical problems, technical solutions and beneficial effects to be solved by the utility model more clearly understood, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0015] In the following description, for the purpose of illustration rather than limitation, specific details such as specific internal procedures and technologies are provided so as to provide a thorough understanding of the embodiments of the utility model. However, it should be clear to those skilled in the art that the utility model can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details that hinder the description of the utility model. The structure and scheme described in the utility model are not only applicable to new energy vehicle drive motors, but also to rotor discharge protection in motors in different industries (automobiles, wind power generation, aircraft, ships, trains, etc.).

[0016] Embodiment 1

[0017] like Figure 1 As shown, this embodiment provides a schematic diagram of a non-contact conductor of a preferred embodiment installed outside the shaft. When the motor is working, due to the imbalance and asymmetry of the motor magnetic circuit and the inability of the modern PWM variable frequency power supply voltage source inverter to produce a completely symmetrical three-phase waveform, the common mode charge 104 is formed and accumulated on the rotor 103. In the case where the conductor is not installed and the insulation treatment is not performed, the common mode charge 104 accumulates to a certain extent, which will break through the lubricating oil film of the main bearing 102 and form a loop to discharge to the motor housing 101. Since the rolling element and the raceway in the main bearing 103 are in point and line contact, the contact surface is extremely small, but a large current density is generated, resulting in local high temperature and burning, damaging the working surface of the main bearing, and causing the main bearing 103 to fail under long-term action.

[0018] In order to prevent the main bearing 103 from electrical corrosion failure, this embodiment uses a conductor composed of an annular liquid-conducting bearing 1, a disc 2, a conductive liquid 3 and a side plate 5 to short-circuit the common mode charge 104 to the grounded motor housing 101. The disc 2 is fixed to the rotor 103 through the shaft end cover 4 or other mechanical means and electrically connected. The disc 2 has a multi-oil blade structure in the forward and reverse directions of the circumference, and is gap-matched with the annular liquid-conducting bearing 1, and forms multiple bidirectional wedge gaps in the circumferential direction. The annular liquid-conducting bearing 1 is fixed to the housing 101 and electrically connected.

[0019] The disc 2 and the annular liquid-conducting bearing 1 are made of metal materials with good electrical conductivity, and the conductive liquid 3 has good electrical conductivity and certain lubricity. When the speed is low, the conductive liquid 3 establishes axial and radial electrical connections between the disc 2 and the annular liquid-conducting bearing 1, and shorts the common-mode charge 104 on the rotor 103 to the grounded motor housing 101. When the motor is working at high speed, the rotor 103 drives the disc 2 to rotate at high speed, and uses the wedge effect of fluid dynamic pressure to form a conductive liquid film 3A on the wedge-shaped gap between the disc 2 and the annular liquid-conducting bearing 1, and establishes radial electrical connection between the disc 2 and the annular liquid-conducting bearing 1, shorting the common-mode charge 104 on the rotor 103 from the disc 2 to the liquid-conducting bearing 1 and grounding through the motor housing 101. Avoid early failure of electrical corrosion caused by frequent contact discharge between the rolling element and the raceway of the rolling bearing 102 supporting the motor rotor 103.

[0020] The annular liquid-conducting bearing 1 and the disc 2 are provided with dynamic sealing structures on both sides to prevent the conductive liquid 3 from being thrown out during the high-speed rotation of the disc 2 or the annular liquid-conducting bearing 1. The filling amount of the conductive liquid 3 should be less than half of the wedge-shaped gap space formed by the disc 2 and the annular liquid-conducting bearing 1.

[0021] Embodiment 2

[0022] like Figure 2 As shown, this embodiment provides a schematic diagram of a non-contact conductor of another preferred embodiment installed in a shaft hole. The difference from the first embodiment is that the annular liquid-conducting bearing is fixed in the inner hole of the rotor 103 and an electrical connection is established. The disc 2 is connected to the grounded housing 101 through a mechanical connector 6. When the motor is working at high speed, the rotor 103 rotates with the annular liquid-conducting bearing 1, and a conductive liquid film 3A is formed on the wedge-shaped gap between the disc 2 and the annular liquid-conducting bearing 1 by utilizing the wedge effect of the fluid dynamic pressure, and the disc 2 establishes a radial electrical connection with the annular liquid-conducting bearing 1, so that the common mode charge 104 on the rotor 103 is short-circuited from the liquid-conducting bearing 1 to the disc 2 and grounded through the motor housing 101.

[0023] In the first and second embodiments, the outer circle of the disk 2 and the inner circle of the annular liquid-conducting bearing 1 can also be combined with different structures to form a plurality of wedge-shaped gap spaces, such as Figure 3 When the outer circle of the disk 2 and the inner circle of the annular liquid-conducting bearing 1 are both complete circular structures, as shown in FIG. Figure 3 As shown in (a), the disc 2 and the annular liquid-conducting bearing 1 need to be installed eccentrically so as to form a wedge-shaped gap in the circumferential direction. The disc 2 is a circular structure, and the inner circle of the annular liquid-conducting bearing 1 is a multi-oil blade structure, such as Figure 3 (b) As shown; when the outer circle of the disk 2 and the inner circle of the annular liquid-conducting bearing 1 are both multi-oil blade structures, as Figure 3 As shown in (c), at this time it is an intermittent conductive state, and the number of oil blades on the disk 2 and the number of oil blades on the annular liquid-conducting bearing 1 may be inconsistent.

[0024] The conductor of the utility model utilizes fluid dynamic pressure conductive liquid film to realize non-contact conduction, thus avoiding wear caused by direct contact of conductive solid materials. It has a simple structure and can realize effective dynamic conduction in all speed sections (low speed, medium speed, high speed) and in forward and reverse rotation. Its conductivity is much higher than the rolling contact conductivity of the rotor-supporting rolling bearing, thus realizing discharge protection for the main bearing of the high-speed motor rotor.

[0025] The preferred specific embodiments of the utility model are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes according to the concept of the utility model without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the utility model on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A non-contact conductor for a motor rotor, characterized in that: The conductor is composed of a disc, an annular liquid-conducting bearing, and conductive liquid; The disc and the annular liquid-conducting bearing are made of metal materials with good electrical conductivity, and are matched in the circumferential direction to form a gap space. By setting a multi-oil blade structure on the inner and outer circumferences of the two or installing the two eccentrically, one or more bidirectional wedge gaps can be formed; One of the disc or annular liquid-conducting bearings is fixedly mounted on the motor rotor, and the other is fixedly mounted on the motor housing; The conductive liquid has good conductivity and certain lubricity, and is filled in the gap formed by the disk and the annular liquid-conducting bearing.

2. The motor rotor non-contact conductor as claimed in claim 1, characterized in that: When the disc is fixed on the outer circle of the motor shaft, the annular liquid-conducting bearing is electromechanically connected to the grounded motor housing; or the annular liquid-conducting bearing is fixed to the inner hole of the motor shaft, and the disc is electromechanically connected to the grounded motor housing.

3. The non-contact conductor for a motor rotor as claimed in claim 1, characterized in that: The inner circle of the annular liquid-conducting bearing and the outer circle of the disc can be a complete circle or a multi-oil blade structure so as to form one or more bidirectional wedge-shaped gaps in the circumferential direction; when the outer circle of the disc and the inner circle of the annular liquid-conducting bearing are both complete circular structures, the disc and the annular liquid-conducting bearing need to be installed eccentrically so as to form a bidirectional wedge-shaped gap in the circumferential direction.

4. The non-contact conductor for a motor rotor as claimed in claim 1, 2 or 3, characterized in that: When the speed is low, the conductive liquid establishes radial and axial electrical connections between the disc and the annular liquid-conducting bearing, and short-circuits the common-mode charge on the motor rotor to the grounded casing. When the speed is high, the rotor drives the disc or the annular liquid-conducting bearing to rotate at high speed, and utilizes the wedge effect of the fluid dynamic pressure to form a conductive liquid film on the wedge-shaped gap between the disc and the annular liquid-conducting bearing, establishes a radial electrical connection between the disc and the annular liquid-conducting bearing, and short-circuits the common-mode charge on the motor rotor to the grounded casing, thereby preventing the motor main bearing from failing due to electrical corrosion due to frequent discharge.

5. The motor rotor non-contact conductor according to claim 1, 2 or 3, characterized in that: The disc has dynamic sealing structures on both sides to prevent the conductive liquid from being thrown out during the high-speed rotation of the disc or the annular liquid-conducting bearing; the filling amount of the conductive liquid should be less than half of the wedge-shaped gap space formed by the disc and the annular liquid-conducting bearing.

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