Shaft end structure for preventing bearing electric corrosion and motor

Abstract

The application discloses a kind of bearing electric corrosion prevention shaft end structure and motor, the structure includes end cover, rotating shaft, bearing, electrically conductive bearing and electrically conductive connection component, rotating shaft end portion has the installation shaft extending outward along axis, the inner ring of electrically conductive bearing is fixedly matched with the outer periphery of installation shaft, the diameter of electrically conductive bearing is less than the diameter of bearing, electrically conductive connection component includes inner ring, outer ring and elastic washer, inner ring is embedded in outer ring and will elastic washer be clamped between two, the inner ring of inner ring is sleeved on the outer ring of electrically conductive bearing, multiple through holes are evenly provided on the inner ring of inner ring, elastic washer is provided with inward protruding portion, protruding portion passes through through hole and is abutted on the outer ring of electrically conductive bearing, outer ring is installed on a ground fixed part.The structure can prevent bearing electric corrosion, and it is little to be affected by rotor axial and radial excursion, reliability is high, and dismounting is convenient.The motor of the application has the above-mentioned shaft end structure, and therefore also has the above-mentioned advantages.

Description

Technical Field

[0001] This invention belongs to the field of drive motor technology, specifically relating to a shaft end structure and motor that prevents bearing electro-corrosion. Background Technology

[0002] Currently, passenger vehicle motor systems use PWM (Pulse Width Modulation) inverter systems to control motor operation. In a PWM inverter system, the common-mode voltage acts on the motor windings, forming a common-mode current path through the coupling capacitors in the motor. Shaft current is a component of this common-mode current. Excessive shaft current can cause bearing electro-corrosion. When the bearing voltage between the inner and outer raceways rises to a certain level, exceeding the lubricating oil film threshold voltage, a breakdown discharge will occur. The short-circuit current generated by this discharge produces enormous heat in a short time, causing the metal near the breakdown point to melt. This leads to a gradual deterioration in the motor bearing's operating condition, shortening its lifespan. Prolonged shaft current can compromise the reliable operation of the motor. Furthermore, as the DC bus voltage increases, the shaft voltage also increases, further increasing the probability of bearing electro-corrosion.

[0003] Common solutions to this problem include using brushes to allow shaft current to pass through them instead of the bearing. However, brushes are prone to wear and require periodic replacement, which is difficult. Another solution is to use insulated bearings to prevent shaft current from being generated by discharge between the inner and outer rings, but insulated bearings are expensive and not widely adopted. Another approach involves incorporating a small conductive bearing and a conductive spring on the motor rotor. The small conductive bearing is positioned inside the rotor's shaft bore, with its outer ring abutting against the inner wall of the bore. A conductive spring is pressed onto the inner ring of the small conductive bearing, with its other end grounded. This allows the shaft current on the rotor to be diverted and discharged through the small conductive bearing and the spring, reducing the current leaking to the main bearing and preventing galvanic corrosion. However, this solution places stress on only one side of the inner ring of the small conductive bearing, raising concerns about bearing reliability over long-term operation. Therefore, finding a simple and effective solution to prevent galvanic corrosion of load-bearing bearings throughout their lifespan remains a pressing issue. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a shaft end structure and motor that are simple in structure, low in cost, and easy to disassemble and maintain to prevent bearing electro-corrosion.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A shaft end structure for preventing bearing electro-corrosion includes an end cover, a rotating shaft, a load-bearing bearing, a conductive bearing, and a conductive connection assembly. The rotating shaft is fixed to the end cover by the load-bearing bearing. The end of the rotating shaft has a mounting shaft extending outward along its axis. The inner ring of the conductive bearing is fixedly fitted with the outer circumference of the mounting shaft. The diameter of the conductive bearing is smaller than the diameter of the load-bearing bearing. The conductive connection assembly includes an inner ring, an outer ring, and an elastic washer. The inner ring is fitted into the outer ring and clamps the elastic washer between them. The inner ring is fitted onto the outer ring of the conductive bearing. Multiple through holes are evenly distributed on the inner ring. The elastic washer has an inwardly protruding portion that protrudes through the through holes and abuts against the outer ring of the conductive bearing. The outer ring is mounted on a grounding fixing part.

[0007] Preferably, in the above-mentioned anti-bearing electro-corrosion shaft end structure, the inner ring member has a first annular end face and a first annular circumferential surface perpendicularly adjacent to the first annular end face, and the outer ring member has a second annular end face and a second annular circumferential surface perpendicularly adjacent to the outer circumference of the second annular end face.

[0008] Preferably, in the above-mentioned anti-bearing electro-corrosion shaft end structure, the first annular circumferential surface includes a first inner annular circumferential surface and a first outer annular circumferential surface. The inner circumference of the first annular end face is adjacent to the first inner annular circumferential surface, and the outer circumference is adjacent to the first outer annular circumferential surface. The through hole is opened on the first inner annular circumferential surface.

[0009] In the aforementioned anti-bearing electro-corrosion shaft end structure, preferably, the outer surface of the first annular end face abuts against the grounding fixing part, and a plurality of mounting parts are uniformly provided on the outer periphery of the opening end of the second annular circumferential face, and the mounting parts are detachably mounted on the grounding fixing part.

[0010] Preferably, in the above-mentioned anti-bearing electro-corrosion shaft end structure, there are at least four mounting parts, and each mounting part is fixed to the grounding fixing part by screws or bolts.

[0011] In the aforementioned anti-bearing electro-corrosion shaft end structure, preferably, the grounding fixing part is an extension of the end cap, the extension extends to the outer ring of the conductive bearing, and the mounting part is mounted on the extension.

[0012] Preferably, in the above-mentioned anti-bearing electro-corrosion shaft end structure, a junction box cover plate is also provided on the outside of the end cover, which together with the end cover forms a closed conductive bearing chamber.

[0013] In the aforementioned shaft end structure for preventing bearing electro-corrosion, preferably, the elastic washer is made of spring steel or conductive rubber.

[0014] Preferably, in the aforementioned anti-bearing electro-corrosion shaft end structure, the inner ring of the conductive bearing is interference-fitted with the mounting shaft.

[0015] As a general technical concept, the present invention also provides an electric motor, including the above-mentioned anti-bearing electro-corrosion shaft end structure, wherein the end cover includes a front end cover and a rear end cover, the front end of the rotating shaft extends out of the front end cover, and the shaft end structure is located at the front end of the rotating shaft.

[0016] In another preferred embodiment of the motor described above, the end cover includes a front end cover and a rear end cover, the rear end of the rotating shaft extends out of the rear end cover, and the shaft end structure is located at the rear end of the rotating shaft.

[0017] In another preferred embodiment of the motor described above, the end cover includes a front end cover and a rear end cover, the front end of the rotating shaft extends out of the front end cover, the rear end of the rotating shaft extends out of the rear end cover, and the shaft end structure consists of two sets, which are respectively installed at the front end and the rear end of the rotating shaft.

[0018] Explanation of relevant terms in this invention:

[0019] DC bus voltage: The voltage supplied by the battery to the electric drive system in the vehicle.

[0020] Load-bearing bearings: bearings that support the motor rotor to bear the radial and axial loads of the motor.

[0021] Compared with the prior art, the advantages of the present invention are as follows:

[0022] (1) The shaft end structure of the present invention uses a conductive connection component to directly guide the shaft current on the rotor to the ground from the end of the shaft. This not only effectively prevents the bearing from electro-corrosion, but also ensures that its structure and performance are not affected by the axial and radial movement of the rotor during motor operation, resulting in good stability.

[0023] Since the axial runout of the shaft is limited by the axial clearance of the bearing, typically within 0.5mm, the influence of axial movement can be effectively overcome by designing sufficient contact points and contact areas between the elastic washer and the conductive bearing. This invention uses a ring-shaped conductive connection assembly, consisting of a conductive inner ring, an outer ring, and an elastic washer, fitted onto the outer ring of the conductive bearing. By adjusting the stiffness of the elastic washer, the inner ring applies a certain radial preload to the conductive bearing. More importantly, the inner ring is fitted into the outer ring, clamping the elastic washer between them. The elastic washer has an inwardly protruding portion that protrudes through a through-hole on the inner ring of the inner ring and abuts against the outer ring of the conductive bearing. This allows the conductive connection assembly to have both radial and axial deformation allowances, ensuring a tight fit with the conductive bearing and uniform stress distribution, while not a completely rigid fit. During motor operation, even with radial and axial movement, the conductive bearing can always be stably and reliably grounded through the conductive connection assembly.

[0024] This invention is the first to use a flexible fitting component to contact the outer ring of a conductive bearing to guide the shaft current. The conductive bearing is subjected to uniform force. This solution has a simple structure, few parts, high reliability, low cost, and is very convenient to install and disassemble, making it easy to maintain later.

[0025] (2) The motor of the present invention also has the above-mentioned advantages of the shaft end structure because it is equipped with the shaft end structure of the present invention. Furthermore, the shaft end structure can effectively prevent the bearing from being electro-corroded, thereby improving the operating stability and service life of the motor. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the shaft end structure for preventing bearing electro-corrosion according to a specific embodiment of the present invention.

[0027] Figure 2 This is a cross-sectional view along line AA of the conductive connection component in the installed state according to a specific embodiment of the present invention.

[0028] Figure 3 This is a three-dimensional structural diagram of the conductive connection component according to a specific embodiment of the present invention. Figure 1 .

[0029] Figure 4 This is a three-dimensional structural diagram of the conductive connection component according to a specific embodiment of the present invention. Figure 2 .

[0030] Figure 5 This is an exploded three-dimensional structural diagram of the conductive connection component according to a specific embodiment of the present invention.

[0031] Figure 6 This is a schematic diagram of the motor structure according to a specific embodiment of the present invention.

[0032] Legend:

[0033] 1. End cap; 10. Extension; 11. Front end cap; 12. Rear end cap; 13. Housing; 14. Stator; 15. Rotor; 2. Shaft; 21. Mounting shaft; 3. Bearing bearing; 31. Front bearing bearing; 32. Rear bearing bearing; 4. Conductive bearing; 5. Conductive connection assembly; 51. Inner ring; 511. First annular end face; 512. First annular circumferential surface; 5121. First inner annular circumferential surface; 5122. First outer annular circumferential surface; 52. Outer ring; 521. Second annular end face; 522. Second annular circumferential surface; 53. Elastic washer; 531. Protrusion; 6. Through hole; 7. Junction box cover; 8. Mounting part. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0035] Figures 1 to 6 An embodiment of the anti-bearing electro-corrosion shaft end structure of the present invention is shown, including an end cover 1, a rotating shaft 2, a bearing 3, a conductive bearing 4, and a conductive connection assembly 5. The rotating shaft 2 is fixed to the end cover 1 by the bearing 3. The end of the rotating shaft 2 has a mounting shaft 21 extending outward along the axis. The inner ring of the conductive bearing 4 is fixedly fitted with the outer circumference of the mounting shaft 21. The diameter of the conductive bearing 4 is smaller than the diameter of the bearing 3. The conductive connection assembly 5 includes an inner ring 51, an outer ring 52, and an elastic washer 53. The inner ring 51 is fitted into the outer ring 52 and the elastic washer 53 is clamped between the two. The inner ring 51 is fitted onto the outer ring of the conductive bearing 4. A plurality of through holes 6 are evenly opened on the inner ring of the inner ring 51. The elastic washer 53 has an inward protrusion 531. The protrusion 531 passes through the through holes 6 and abuts against the outer ring of the conductive bearing 4. The outer ring 52 is mounted on a grounding fixing part.

[0036] Taking an electric motor as a specific application example, the motor includes a housing 13, a stator 14, a rotor 15, a shaft 2, and an end cover 1. The end cover 1 includes a front cover 11 and a rear cover 12. The front cover 11 and the rear cover 12 are respectively fixed on the housing 13. The two ends of the shaft 2 are respectively mounted on the front cover 11 and the rear cover 12 through two bearings 3. The rotor 15 is fixed on the shaft 2. The stator 14 is located on the outer periphery of the rotor 15. The shaft end structure that prevents bearing electro-corrosion is installed at the end of the shaft 2.

[0037] During motor operation, the conductive bearing 4, the front bearing 31, and the rear bearing 32 are all on the rotor 15, forming an equipotential body. The stator 14, housing 13, front cover 11, rear cover 12, grounding fixing part, and conductive connection assembly 5 are connected together, forming another equipotential body. The motor housing 13 is grounded, and its potential is zero. Therefore, the potentials of the conductive bearing 4, the front bearing 31, and the rear bearing 32 relative to ground are equal, meaning their shaft voltages are equal. Because the diameter of the conductive bearing 4 is smaller than that of the front bearing 31 and the rear bearing 32, under the same shaft voltage, the conductive bearing 4 is more prone to discharge, i.e., shaft current. The shaft current flows through the conductive bearing 4 to the conductive connection assembly 5, then through the conductive connection assembly 5 to the grounding fixing part, and finally to ground. When discharge occurs in the conductive bearing 4, discharge will not occur in the front bearing 31 and the rear bearing 32, thus protecting the front and rear bearings and preventing bearing electrolytic corrosion.

[0038] An annular conductive connection assembly 5, consisting of an inner ring 51, an outer ring 52, and an elastic washer 53, is fitted onto the outer ring of the conductive bearing 4. By adjusting the stiffness of the elastic washer 53, the inner ring 51 applies a certain radial preload to the conductive bearing 4. More importantly, the inner ring 51 is fitted into the outer ring 52 and clamps the elastic washer 53 between them. The elastic washer 53 has an inward protrusion 531, which protrudes through the through hole 6 on the inner ring of the inner ring 51 and abuts against the outer ring of the conductive bearing 4. This allows the conductive connection assembly 5 to have both radial and axial deformation allowances, ensuring a tight fit with the conductive bearing and uniform force distribution. However, it is not a completely rigid fit. During motor operation, even if there is radial and axial movement, the conductive bearing 4 can always be stably and reliably grounded through the conductive connection assembly 5.

[0039] In this embodiment, the inner ring member 51 has a first annular end face 511 and a first annular circumferential surface 512 perpendicularly adjacent to the first annular end face 511, and the outer ring member 52 has a second annular end face 521 and a second annular circumferential surface 522 perpendicularly adjacent to the outer periphery of the second annular end face 521. The interlocking of the two sets of mutually perpendicular annular end faces and annular circumferential surfaces can provide the conductive bearing with stronger axial support force.

[0040] In this embodiment, the first annular circumferential surface 512 includes a first inner annular circumferential surface 5121 and a first outer annular circumferential surface 5122. The inner circumference of the first annular end face 511 is adjacent to the first inner annular circumferential surface 5121, and the outer circumference is adjacent to the first outer annular circumferential surface 5122. The through hole 6 is opened on the first inner annular circumferential surface 5121.

[0041] In this embodiment, the outer surface of the first annular end face 511 abuts against the grounding fixing part, and a plurality of mounting parts 8 are uniformly provided on the outer periphery of the opening end of the second annular circumferential surface 522. The mounting parts 8 are detachably mounted on the grounding fixing part.

[0042] In this embodiment, there are at least four mounting parts 8, and each mounting part 8 is fixed to the grounding fixing part by screws.

[0043] In this embodiment, the grounding fixing part is the extension 10 of the end cover 1, which extends to the outer ring of the conductive bearing 4. The mounting part 8 is mounted on the extension 10. The outer side of the end cover 1 is also provided with a junction box cover 7, which together with the end cover 1 forms a closed conductive bearing chamber. The junction box cover 7 is grounded.

[0044] Since the junction box cover 7 and the end cover 1 form a closed conductive bearing chamber with independent space, installation and disassembly can be carried out simply by removing the junction box cover 7. The structure is simple and the disassembly and assembly are very convenient. It can also play a role in preventing dust and dirt.

[0045] In other embodiments, the grounding fixing part may be an extension 10 of the end cover 1, which extends to the outer ring of the conductive bearing 4, and the mounting part 8 is mounted on the extension 10, with the end cover 1 grounded.

[0046] In this embodiment, the elastic washer 53 is made of spring steel.

[0047] In this embodiment, the inner ring of the conductive bearing 4 is interference-fitted with the mounting shaft 21.

[0048] A type of motor, such as Figure 6 As shown, the shaft end structure for preventing bearing electro-corrosion in this embodiment includes a front cover 11 and a rear cover 12. The rear end of the rotating shaft 2 extends out of the rear cover 12. The junction box cover is fixed to the outside of the rear cover 12. The shaft end structure is located between the rear end of the rotating shaft 2 and the junction box cover.

[0049] The motor of the present invention has the advantages of a shaft end structure that prevents bearing electro-corrosion, and the shaft end structure can effectively prevent bearing electro-corrosion of the bearing 3, thereby improving the operating stability and service life of the motor.

[0050] In other embodiments, the shaft end structure for preventing bearing electro-corrosion can also be set at the front end of the rotating shaft 2. Specifically, the front end of the rotating shaft 2 extends out of the front end cover 11, the junction box cover is fixed on the outside of the front end cover 11, and the shaft end structure is located between the front end of the rotating shaft 2 and the junction box cover.

[0051] In other embodiments, anti-bearing electro-corrosion shaft end structures can also be provided at both the front and rear ends of the rotating shaft 2.

[0052] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. The technical features involved in the various embodiments of the present invention described above can be combined with each other as long as they do not conflict with each other. All technical solutions within the scope of the present invention's concept are within the protection scope of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should be considered within the protection scope of the present invention.

Claims

1. A shaft end structure for preventing bearing current corrosion, characterized by: The assembly includes an end cap (1), a rotating shaft (2), a bearing (3), a conductive bearing (4), and a conductive connection assembly (5). The rotating shaft (2) is fixed to the end cap (1) via the bearing (3). The end of the rotating shaft (2) has a mounting shaft (21) extending outward along its axis. The inner ring of the conductive bearing (4) is fixedly fitted with the outer circumference of the mounting shaft (21). The diameter of the conductive bearing (4) is smaller than the diameter of the bearing (3). The conductive connection assembly (5) includes an inner ring (51), an outer ring (52), and an elastic washer (53). The inner ring (51) is fitted into the outer ring (52) and clamps the elastic washer (53) between them. The inner ring of the inner ring (51) is fitted onto the outer ring of the conductive bearing (4). The inner ring (51) has multiple through holes (6) evenly distributed on its inner ring. The elastic washer (53) has an inwardly facing... A protrusion (531) protrudes through the through hole (6) and abuts against the outer ring of the conductive bearing (4). The outer ring (52) is mounted on a grounding fixing part. The inner ring (51) has a first annular end face (511) and a first annular circumferential surface (512) perpendicularly adjacent to the first annular end face (511). The outer ring (52) has a second annular end face (521) and a second annular circumferential surface (522) perpendicularly adjacent to the outer circumference of the second annular end face (521). The first annular circumferential surface (512) includes a first inner annular circumferential surface (5121) and a first outer annular circumferential surface (5122). The inner circumference of the first annular end face (511) is adjacent to the first inner annular circumferential surface (5121), and the outer circumference is adjacent to the first outer annular circumferential surface (5122). The through hole (6) is opened on the first inner annular circumferential surface (5121).

2. A shaft end construction for protection against electric bearing corrosion according to claim 1, characterized in that The outer surface of the first annular end face (511) abuts against the grounding fixing part, and a plurality of mounting parts (8) are uniformly provided on the outer periphery of the opening end of the second annular circumferential surface (522), and the mounting parts (8) are detachably mounted on the grounding fixing part.

3. A shaft end construction for protection against electric bearing corrosion according to claim 2, characterized in that There are at least four mounting parts (8), and each mounting part (8) is fixed to the grounding fixing part by screws or bolts.

4. A shaft end construction for protection against electric bearing corrosion according to claim 3, characterized in that The grounding fixing part is an extension (10) of the end cap (1), the extension (10) extends to the outer ring of the conductive bearing (4), and the mounting part (8) is mounted on the extension (10).

5. A shaft end construction for protection against electric corrosion of a bearing according to claim 4, characterized in that The end cover (1) is also provided with a junction box cover plate (7) on the outside, which together with the end cover (1) forms a closed conductive bearing chamber.

6. A shaft end construction for protection against electrocorrosion of a bearing according to any one of claims 2 to 5, characterized in that: The elastic gasket (53) is made of conductive rubber or conductive metal material.

7. A shaft end construction for protection against electric bearing corrosion according to claim 6, characterized in that The conductive metal material is spring steel.

8. A shaft end construction for protection against electrocorrosion of a bearing according to any one of claims 2 to 5, characterized in that: The inner ring of the conductive bearing (4) is interference-fitted with the mounting shaft (21).

9. An electric machine characterized by The shaft end structure for preventing bearing electro-corrosion as described in any one of claims 1 to 8, wherein the end cover (1) includes a front end cover (11) and a rear end cover (12), the front end of the rotating shaft (2) extends out of the front end cover (11), and the shaft end structure is located at the front end of the rotating shaft (2); And / or, the end cover (1) comprises a front end cover (11) and a rear end cover (12), the rear end of the rotating shaft (2) extends out of the rear end cover (12), and the shaft end structure is located at the rear end of the rotating shaft (2).

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