Deep groove ball bearing for a wheel hub motor

Abstract

This utility model discloses a deep groove ball bearing for hub motors, comprising an outer ring, an inner ring, steel balls, a cage, and a bearing seal. An annular stepped groove is provided at the connection between one axial outer end face of the inner ring and its inner diameter surface. An elastic seal is installed within the stepped groove, with its outer lip interfering with the inner diameter surface of the stepped groove. A sealing lip is provided on the radially inner side of the elastic seal, which forms an interference fit seal with the motor shaft mounted inside the inner ring. The axial outer end face of the elastic seal extends to the axial outer side of the stepped groove, and is used to make tight contact with the shoulder end face of the motor shaft to achieve axial preload on the bearing. This deep groove ball bearing can suppress resonance and noise generated by hub motors during high-speed operation, extending the service life of hub motors by more than 30%, and better meeting the requirements of applications such as electric bicycles that have high requirements for the noise and service life of hub motors.

Description

Technical Field

[0001] This utility model relates to a bearing, specifically a deep groove ball bearing for a hub motor. Background Technology

[0002] Typical hub motors use a shaft-based design, where the outer bearing ring is fixed and the inner ring rotates. The motor shaft and the bearing's inner diameter surface have an interference fit, while the bearing housing and the bearing's outer diameter surface have a clearance fit. Due to the relatively large internal space of the bearing housing, axial preload can usually be achieved by adding flat or corrugated shims. However, some small hub motors use a hole-based design, where the outer ring rotates and the inner ring is fixed. The bearing housing and the bearing's outer diameter surface have an interference fit, while the motor shaft and the bearing's inner diameter surface have a clearance fit. This hole-based design makes bearing machining more difficult, axial clearance harder to control, and the compact internal space makes it difficult to achieve axial preload by adding shims. Furthermore, high-speed hub motor bearings using the hole-based design are prone to resonance due to their structural characteristics, resulting in abnormal noise. In addition, the inner and outer raceways of hub motor bearings typically adopt a standard curvature design, that is, the curvature radius of the inner raceway is 0.515 times the diameter of the steel ball, and the curvature radius of the outer raceway is 0.525 times the diameter of the steel ball. This standardized design limits the self-aligning performance of the bearing to a certain extent and places higher demands on the concentricity of the bearing installation.

[0003] Taking electric bicycle hub motors as an example, the above factors often manifest as two major problems: First, at high speeds, insufficient axial preload after bearing installation can easily cause resonance and generate abnormal noise, seriously affecting the use and lifespan of the hub motor; Second, if the bearing housings of the end caps of the hub motor are not concentric, the bearing rings will tilt, which will also lead to abnormal noise. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide a deep groove ball bearing for hub motors, which can suppress the resonance and noise generated by hub motors when they are running at high speeds, extend the service life of hub motors by more than 30%, and better meet the application requirements of electric bicycles and other applications that have high requirements for the noise and service life of hub motors.

[0005] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows: a deep groove ball bearing for a hub motor, comprising an outer ring, an inner ring, steel balls, a cage, and a bearing seal ring. The outer ring is disposed outside the inner ring. The cage and the bearing seal ring are respectively installed between the outer ring and the inner ring. The steel balls are installed on the cage. The outer lip of the bearing seal ring contacts and seals with the outer ring. The inner lip of the bearing seal ring contacts and seals with the inner ring. An annular stepped groove is provided at the connection between an axial outer end face and an inner diameter face of the inner ring. An elastic seal ring is installed in the stepped groove. The outer lip of the elastic seal ring is interference-fitted with the inner diameter face of the stepped groove. A sealing lip is provided on the radial inner side of the elastic seal ring. The sealing lip is used to form an interference-fit seal with the motor shaft installed inside the inner ring. The axial outer end face of the elastic seal ring extends to the axial outer side of the stepped groove. The axial outer end face of the elastic seal ring is used to make tight contact with the shoulder end face of the motor shaft to achieve axial preload on the bearing.

[0006] This invention achieves axial preload on the bearing by creating an annular stepped groove at the junction of the outer axial end face and the inner diameter surface of the bearing's inner ring, and installing an elastic sealing ring within the stepped groove. In its natural state, the outer axial end face of the elastic sealing ring extends to the outer axial side of the stepped groove. During motor shaft assembly, the shoulder end face of the motor shaft contacts the outer axial end face of the elastic sealing ring. After the motor assembly is locked, the shoulder end face of the motor shaft applies pressure to the outer axial end face of the elastic sealing ring, causing axial compression of the elastic sealing ring and thus applying an axial preload force to the inner ring of the bearing. This axial preload force effectively eliminates internal clearance in the bearing and increases bearing rigidity, thereby suppressing resonance and noise generated by the hub motor during high-speed operation.

[0007] Preferably, the outer lip of the elastic sealing ring includes several raised rings, which are interference-fitted with the inner diameter surface of the stepped groove. By adopting the aforementioned design of several raised rings, the radial sealing reliability is improved, the positioning firmness of the elastic sealing ring within the stepped groove is enhanced, loosening of the elastic sealing ring under vibration is prevented, and dimensional tolerances are better compensated.

[0008] Preferably, the elastic sealing ring consists of a metal insert and rubber covering the periphery of the metal insert. The metal insert can be made of a known metal material with certain strength and elasticity, for example, heat-treated 65Mn spring steel.

[0009] Preferably, the sealing lip is angled radially inward towards the inner ring. Combined with the oil seal between the motor shaft and the bearing housing (which, after assembly, is located on the outer side of the other axial outer end face of the inner ring of the bearing), it provides dual protection, preventing mud, water, impurities, etc., from entering the hub motor. Even after the oil seal wears down, the sealing lip still provides protection, thereby extending the service life of the hub motor.

[0010] As a further preferred embodiment, the interference fit between the sealing lip and the outer diameter surface of the motor shaft is 0.1 to 0.2 mm.

[0011] Preferably, the inner ring groove curvature radius of this deep groove ball bearing is 0.53 times the diameter of the steel ball, and the outer ring groove curvature radius is 0.54 times the diameter of the steel ball. Compared with the traditional design where the inner ring groove curvature radius and the outer ring groove curvature radius are 0.515 times and 0.525 times respectively, this invention, by increasing the inner ring groove curvature radius and the outer ring groove curvature radius, effectively improves the bearing's fatigue life while significantly enhancing its self-aligning performance. This allows for better compensation of concentricity errors during bearing installation and reduces abnormal bearing noise caused by poor concentricity.

[0012] Compared with existing technologies, this invention has the following advantages: This invention achieves axial preload by setting an annular stepped groove at the connection between the outer axial end face and the inner diameter face of the bearing's inner ring, and installing an elastic sealing ring within the stepped groove. This effectively eliminates internal clearance in the bearing and increases bearing rigidity, thereby suppressing resonance and noise generated by the hub motor during high-speed operation. The hub motor requires no modification to any existing motor components; simply replacing them with this deep groove ball bearing achieves axial preload and improves self-aligning performance, effectively reducing resonance noise and extending the hub motor's service life by more than 30%. This better meets the requirements of applications such as electric bicycles that demand high noise levels and long service life from hub motors. Attached Figure Description

[0013] Figure 1 This is a cross-sectional view of the deep groove ball bearing in the embodiment;

[0014] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0015] Figure 3 This is a schematic diagram showing the effect of the deep groove ball bearing and the motor shaft after initial assembly in the embodiment;

[0016] Figures 1-3 The specific reference numerals in the attached figures are as follows:

[0017] 1-Outer ring, 11-Outer ring groove curvature, 2-Inner ring, 21-Inner ring groove curvature, 22-Step groove, 3-Steel ball, 4-Cage, 5-Bearing seal ring, 51-Outer lip, 52-Inner lip, 6-Elastic seal ring, 61-Metal insert, 62-Rubber, 63-Raised ring, 64-Sealing lip, 7-Motor shaft, 71-Shoulder end face, 8-Bearing housing, 9-Oil seal. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0019] The deep groove ball bearing for the hub motor in the embodiment, such as Figure 1 and Figure 2 As shown, the bearing includes an outer ring 1, an inner ring 2, a steel ball 3, a cage 4, and a bearing seal 5. The outer ring 1 is located outside the inner ring 2. The radius of curvature 21 of the inner ring groove is 0.53 times the diameter of the steel ball 3, and the radius of curvature 11 of the outer ring groove is 0.54 times the diameter of the steel ball 3. The cage 4 and the bearing seal 5 are respectively installed between the outer ring 1 and the inner ring 2. The steel ball 3 is installed on the cage 4. The outer lip 51 of the bearing seal 5 contacts and seals with the outer ring 1, and the inner lip 52 of the bearing seal 5 contacts and seals with the inner ring 2. An annular stepped groove 22 is provided at the connection between one axial outer end face and the inner diameter face of the inner ring 2. An elastic seal 6 is installed in the stepped groove 22. The elastic seal 6 consists of a metal insert 61 and a rubber 62 covering the metal insert 61. In this embodiment, the metal insert 61 is made of heat-treated 65Mn spring steel, the rubber 62 is made of nitrile rubber (NBR), the outer lip of the elastic sealing ring 6 includes two convex rings 63, which are interference-fitted with the inner diameter surface of the stepped groove 22, and the radial inner side of the elastic sealing ring 6 is provided with a sealing lip 64, which is inclined towards the radial inner side of the inner ring 2. The sealing lip 64 is used to form an interference fit seal with the motor shaft 7 installed on the inner side of the inner ring 2 with an interference amount of 0.1 to 0.2 mm, and the axial outer end face of the elastic sealing ring 6 extends to the axial outer side of the stepped groove 22 by 0.5 mm. The axial outer end face of the elastic sealing ring 6 is used to make tight contact with the shoulder end face 71 of the motor shaft 7 to achieve axial preload on the bearing.

[0020] In its natural state, the axial outer end face of the elastic seal ring 6 of the deep groove ball bearing extends to the axial outer side of the stepped groove 22. A schematic diagram showing the effect of the deep groove ball bearing after initial assembly with the motor shaft 7 is shown below. Figure 3During the assembly of the motor shaft 7, the shoulder end face 71 of the motor shaft 7 contacts the axial outer end face of the elastic seal ring 6. After the motor assembly is locked, the shoulder end face 71 of the motor shaft 7 applies pressure to the axial outer end face of the elastic seal ring 6, causing the elastic seal ring 6 to be axially compressed, thereby applying an axial preload to the inner ring 2 of the bearing. This axial preload can effectively eliminate the internal clearance of the bearing and increase the rigidity of the bearing, thereby suppressing the resonance and noise generated by the hub motor during high-speed operation.

[0021] Furthermore, after the motor is assembled and locked, the sealing lip 64 of the elastic sealing ring 6 forms an interference fit seal with the motor shaft 7, which, together with the oil seal 9 between the motor shaft 7 and the bearing chamber 8 (the oil seal 9 is located on the outer side of the other axial outer end face of the inner ring 2 of the bearing), can play a double protection role, preventing mud, water, impurities and other contaminants from entering the hub motor. Even after the oil seal 9 wears, the sealing lip 64 can still play a protective role, thereby improving the service life of the hub motor.

[0022] The hub motor requires no changes to any existing motor parts; simply replacing them with the aforementioned deep groove ball bearings will achieve axial preload and improve self-aligning performance, effectively reducing resonance noise and extending the hub motor's service life by more than 30%. This better meets the needs of applications such as electric bicycles that have high requirements for the noise and service life of hub motors.

Claims

1. A deep groove ball bearing for a hub motor, comprising an outer ring, an inner ring, steel balls, a cage, and a bearing seal ring, wherein the outer ring is disposed outside the inner ring, the cage and the bearing seal ring are respectively installed between the outer ring and the inner ring, the steel balls are mounted on the cage, the outer lip of the bearing seal ring contacts and seals with the outer ring, and the inner lip of the bearing seal ring contacts and seals with the inner ring, characterized in that... An annular stepped groove is provided at the connection between the outer axial end face of the inner ring and the inner diameter face. An elastic sealing ring is installed in the stepped groove. The outer lip of the elastic sealing ring is interference-fitted with the inner diameter face of the stepped groove. A sealing lip is provided on the radially inner side of the elastic sealing ring. The sealing lip is used to form an interference fit seal with the motor shaft installed inside the inner ring. The outer axial end face of the elastic sealing ring extends to the outer axial side of the stepped groove. The outer axial end face of the elastic sealing ring is used to make tight contact with the shoulder end face of the motor shaft to achieve axial preload on the bearing.

2. The deep groove ball bearing for a hub motor according to claim 1, characterized in that, The outer lip of the elastic sealing ring includes several raised rings, which are interference-fitted with the inner diameter surface of the stepped groove.

3. The deep groove ball bearing for a wheel hub motor according to claim 1, wherein The elastic sealing ring consists of a metal insert and rubber covering the periphery of the metal insert.

4. The deep groove ball bearing for a hub motor according to claim 1, characterized in that, The sealing lip is angled toward the radially inner side of the inner ring.

5. The deep groove ball bearing for a hub motor according to claim 4, characterized in that, The interference fit between the sealing lip and the outer diameter surface of the motor shaft is 0.1 to 0.2 mm.

6. The deep groove ball bearing for a hub motor according to claim 1, characterized in that, The inner ring groove curvature radius of this deep groove ball bearing is 0.53 times the diameter of the steel ball, and the outer ring groove curvature radius is 0.54 times the diameter of the steel ball.

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