A hub bearing with variable raceway curvature

Abstract

This invention relates to the field of wheel hub bearing technology, specifically to a wheel hub bearing with variable raceway curvature. A wheel hub bearing with variable raceway curvature includes an outer ring unit, an inner ring unit, and a plurality of balls. The outer ring unit includes a bearing outer ring; the outer ring has an inner outer ring groove and an outer outer ring groove. The inner ring unit includes an inner ring flange and a mating inner ring; the inner ring flange has a flange groove; the mating inner ring has an inner ring groove; a portion of the balls are located between the inner ring groove and the outer ring inner groove, and another portion of the balls are located between the flange groove and the outer ring outer groove; wherein, the axis of the bearing outer ring is located in a reference section; in the reference section, the outer ring inner groove has a first section line; the first section line includes a first curve and a second curve; the radius of curvature of the first curve is greater than the radius of curvature of the second curve; thus solving the problem of how to balance frictional torque and axial load capacity to improve the service life of the wheel hub bearing.

Description

Technical Field

[0001] This invention relates to the field of wheel hub bearing technology, and more specifically, to a wheel hub bearing with variable raceway curvature. Background Technology

[0002] Wheel bearings are crucial components in machinery used in transportation, engineering, and agriculture. Essentially, they are bearing units integrating an inner ring, outer ring, rolling elements, cage, and seals. For example, in automobiles, wheel bearings connect the steering knuckle to the wheel hub, supporting the vehicle's weight while providing low-friction, high-precision guidance for the high-speed rotation of the wheels. They are key components in achieving coordinated load-bearing and wheel rotation. The rolling elements are typically mounted between the inner and outer rings' grooves, allowing relative rotation between them. The rolling elements are usually steel balls.

[0003] The heat generated by the frictional torque between the steel balls and the raceway during vehicle operation is a key factor affecting the service life of wheel hub bearings. When a wheel turns or collides with an obstacle, it experiences significant axial acceleration, making the axial load capacity of the wheel hub bearing another crucial factor influencing its lifespan. However, the raceway of a wheel hub bearing typically has a single radius of curvature, and the contact area between the steel balls and the raceway usually does not change significantly during vehicle operation. If the contact area is designed to be too large, it will result in a high frictional torque; conversely, if the contact area is designed to be too small, it will reduce the axial load capacity of the wheel hub bearing. Therefore, balancing the impact of frictional torque and axial load capacity on the service life of wheel hub bearings is a critical technical problem that urgently needs to be solved. Summary of the Invention

[0004] To address the challenge of balancing frictional torque and axial load capacity to improve the service life of wheel hub bearings, this invention provides a wheel hub bearing with variable raceway curvature, comprising:

[0005] An outer ring unit, the outer ring unit including a bearing outer ring; the bearing outer ring has an inner outer ring groove and an outer outer ring groove inside;

[0006] An inner ring unit is located inside the outer ring unit; the inner ring unit includes an inner ring flange and a mating inner ring; the mating inner ring is fixedly connected to the inner ring flange; the inner ring flange has a flange groove; the mating inner ring has an inner ring groove; the bearing outer ring, the mating inner ring, and the inner ring flange are coaxially arranged.

[0007] Multiple spheres, a portion of which are located between the inner ring groove and the inner outer ring groove, and another portion of which are located between the flange groove and the outer outer ring groove;

[0008] The axis of the outer ring of the bearing is located in a reference section; in the reference section, the inner groove of the outer ring has a first section line, the inner groove of the inner ring has a second section line, the outer groove of the outer ring has a third section line, and the flange groove has a fourth section line; the radii of curvature of the first section line, the second section line, the third section line, and the fourth section line are all greater than the radius of the sphere;

[0009] The first cross-sectional line includes a first curve and a second curve; the radius of curvature of the first curve is greater than the radius of curvature of the second curve; the end of the first curve near the outer groove of the outer ring is connected to the second curve.

[0010] In some embodiments, the arc length of the first curve is greater than the arc length of the second curve; the angle between the tangent of the first curve near the endpoint of the outer groove of the outer ring and the axis of the bearing outer ring is less than 90°.

[0011] In some embodiments, the first cross-sectional line further includes a first straight line; one end of the first straight line is connected to the second curve; the first straight line is tangent to the second curve; and the angle between the first straight line and the axis of the outer ring of the bearing is less than 90°.

[0012] In some embodiments, the ratio of the length of the first straight line to the arc length of the second curve is between 0.15 and 0.35.

[0013] In some embodiments, the second cross-sectional line includes a third curve and a fourth curve; the radius of curvature of the third curve is greater than the radius of curvature of the fourth curve; the end of the fourth curve near the flange groove is connected to the third curve.

[0014] In some embodiments, the radius of curvature of the third curve is smaller than that of the first curve; the radius of curvature of the third curve is larger than that of the second curve.

[0015] In some embodiments, the second cross-sectional line further includes a second straight line; one end of the second straight line is connected to the fourth curve; the second straight line is tangent to the fourth curve; and the angle between the second straight line and the axis of the mating inner ring is less than 90°.

[0016] In some embodiments, the arc length of the third curve is less than the arc length of the fourth curve; the tangent of the third curve near the end of the flange groove is parallel to the axis of the mating inner ring.

[0017] In some embodiments, the third cross-sectional line includes a fifth curve and a sixth curve; the radius of curvature of the fifth curve is greater than the radius of curvature of the sixth curve; the end of the fifth curve near the inner channel of the outer ring is connected to the sixth curve;

[0018] The ratio of the arc length of the second curve to the arc length of the first curve is the first ratio; the ratio of the arc length of the sixth curve to the arc length of the fifth curve is the second ratio; the first ratio is greater than the second ratio.

[0019] In some embodiments, the fourth cross-sectional line includes a seventh curve and an eighth curve; the radius of curvature of the seventh curve is greater than the radius of curvature of the eighth curve; the end of the eighth curve near the inner channel is connected to the seventh curve;

[0020] The ratio of the arc length of the fourth curve to the arc length of the third curve is the third ratio; the ratio of the arc length of the eighth curve to the arc length of the seventh curve is the fourth ratio; the third ratio is greater than the fourth ratio.

[0021] To address the challenge of balancing frictional torque and axial load capacity to improve the service life of wheel hub bearings, this invention offers the following advantages:

[0022] This application sets the first cross-sectional line of the inner groove of the outer ring as a first curve and a second curve, with the radius of curvature of the first curve being greater than that of the second curve. The end of the first curve near the outer groove of the outer ring connects with the second curve. In other words, the radius of curvature of the inner groove of the outer ring in this application is designed as a variable curvature design that varies along the axial direction of the wheel hub bearing, making the radius of curvature of the inner groove of the outer ring gradually decrease towards the outer groove of the outer ring. For most of the time, the vehicle travels in a straight line. During straight-line travel, the first curve area of ​​the inner groove of the outer ring contacts the ball, and the contact area is small, thus reducing the frictional torque during long-term travel. When the vehicle is turning or the wheel hits an obstacle, the steel ball contacts the second curve area of ​​the inner groove of the outer ring, resulting in a larger contact area, thereby improving the axial load-bearing capacity of the inner groove of the outer ring of the wheel hub bearing. Therefore, the variable curvature design of the inner groove of the outer ring enables the wheel hub bearing to dynamically change the contact area between the ball and the groove under different driving conditions of the vehicle, thus balancing frictional torque and axial load-bearing capacity, and improving the service life of the wheel hub bearing. The inner groove of the wheel hub bearing is closer to the center of the vehicle and bears a greater axle load. This application designs the inner groove of the outer ring with variable curvature, which can significantly increase the dynamic variation of the contact area between the steel balls and the groove, thereby maximizing the service life of the wheel hub bearing. Furthermore, compared to the inner ring unit, the outer ring unit is more susceptible to external impacts. Designing the inner groove of the outer ring with variable curvature in this application can reduce frictional torque while improving the impact resistance of the outer ring unit. This further extends the service life of the wheel hub bearing. Attached Figure Description

[0023] Figure 1 A cross-sectional schematic diagram of a wheel hub bearing with variable raceway curvature according to Embodiment 1 is shown;

[0024] Figure 2 It shows Figure 1 A simplified schematic diagram of the first cross-section line in the diagram;

[0025] Figure 3 It shows Figure 1 A simplified schematic diagram of the second cross-section line in the diagram;

[0026] Figure 4 It shows Figure 1 A simplified schematic diagram of the third section line in the diagram;

[0027] Figure 5 It shows Figure 1 A simplified schematic diagram of the fourth section line.

[0028] Reference numerals: 10 Outer ring unit; 11 Bearing outer ring; 12 Inner groove of outer ring; 13 Outer groove of outer ring; 14 First section line; 141 First curve; 142 Second curve; 143 First straight line; 15 Third section line; 151 Fifth curve; 152 Sixth curve; 153 Third straight line; 20 Inner ring unit; 21 Inner ring flange; 22 Mating inner ring; 23 Flange groove; 24 Inner ring groove; 25 Second section line; 251 Third curve; 252 Fourth curve; 253 Second straight line; 26 Fourth section line; 261 Seventh curve; 262 Eighth curve; 263 Fourth straight line; 30 Ball. Detailed Implementation

[0029] The present disclosure will now be discussed with reference to several exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and thus implement the present disclosure, and are not intended to imply any limitation on the scope of the disclosure.

[0030] As used herein, the term "comprising" and its variations are to be interpreted as open-ended terms meaning "including but not limited to". The term "based on" is to be interpreted as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment". The term "another embodiment" is to be interpreted as "at least one other embodiment". The terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "vertical", "horizontal", "lateral", "longitudinal", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments and are not intended to limit the indicated devices, elements, or components to having a specific orientation or being constructed and operated in a specific orientation. Furthermore, some of the above terms may be used to indicate other meanings besides orientations or positional relationships; for example, the term "upper" may in some cases indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application according to the specific circumstances. In addition, the terms "installed", "set up", "equipped with", "connected", and "linked" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, elements, or components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. Furthermore, the terms "first," "second," etc., are mainly used to distinguish different devices, elements, or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0031] Wheel hub bearings are crucial components in mechanical equipment used in transportation, engineering, and agriculture. They are bearing units composed of an inner ring, outer ring, rolling elements, cage, and seals. When installed in automobiles, wheel hub bearings connect the steering knuckle to the wheel hub. Typically, the rolling elements are installed between the raceways of the inner and outer rings, allowing relative rotation between them. Because the radius of curvature of a single raceway is usually a fixed value, the frictional torque of the wheel hub bearing is relatively high during vehicle operation, and its axial load-bearing capacity needs improvement. To address the problem of balancing frictional torque and axial load-bearing capacity to improve the service life of wheel hub bearings, this invention provides a wheel hub bearing with variable raceway curvature.

[0032] Example 1:

[0033] In this embodiment, as Figure 1As shown, a wheel hub bearing with variable raceway curvature includes an outer ring unit 10, an inner ring unit 20, and a plurality of balls 30.

[0034] The outer ring unit 10 includes a bearing outer ring 11; the bearing outer ring 11 has two channels inside, namely an inner outer ring channel 12 and an outer outer ring channel 13.

[0035] The inner ring unit 20 is located inside the outer ring unit 10; the inner ring unit 20 includes an inner ring flange 21 and a mating inner ring 22; the mating inner ring 22 is fixedly connected to the inner ring flange 21; the mating inner ring 22 can be press-fitted to the inner ring flange 21, then the mating inner ring 22 can be rolled and aligned with the inner ring flange 21 for limiting and fixing. The inner ring flange 21 has a flange groove 23; the mating inner ring 22 has an inner ring groove 24; the bearing outer ring 11, the mating inner ring 22, and the inner ring flange 21 are coaxially arranged.

[0036] One part of the sphere 30 is located between the inner ring groove 24 and the inner outer ring groove 12, and the other part of the sphere 30 is located between the flange groove 23 and the outer outer ring groove 13; in this way, the sphere 30 can be installed between the outer ring unit 10 and the inner ring unit 20, and the outer ring unit 10 and the inner ring unit 20 can rotate relative to each other on the same axis.

[0037] When wheel bearings are installed on vehicles such as automobiles, the outer ring unit 10 is fixedly connected to the steering knuckle or axle head of the vehicle, which is connected to the drive shaft, while the inner ring unit 20 is fixedly connected to the wheel hub of the vehicle. This allows the power from the drive shaft to be transmitted to the wheel hub, thereby driving the wheel to rotate. At this time, the wheel bearing, wheel hub, and wheel are coaxial.

[0038] In this bearing, the axis of the outer ring 11 is located in the reference section. In the reference section, the inner groove 12 of the outer ring has a first section line 14, the inner groove 24 has a second section line 25, the outer groove 13 of the outer ring has a third section line 15, and the flange groove 23 has a fourth section line 26. The radii of curvature of the first section line 14, the second section line 25, the third section line 15, and the fourth section line 26 are all greater than the radius of the ball 30. This makes the ball 30 in point contact with the inner groove 12, the inner groove 24, the outer groove 13, and the flange groove 23. However, after the hub bearing is installed, due to the compression between the ball 30 and the outer ring unit 10 and the inner ring unit 20, the ball 30 forms an elliptical contact surface with the inner groove 12, the inner groove 24, the outer groove 13, and the flange groove 23, which is referred to as a contact ellipse.

[0039] like Figure 2As shown, the first cross-sectional line 14 includes a first curve 141 and a second curve 142. The radius of curvature of the first curve 141 is greater than that of the second curve 142; the end of the first curve 141 near the outer outer channel 13 connects with the second curve 142. This makes the curvature of the inner outer channel 12 of the outer ring a variable curvature, rather than a single curvature.

[0040] During vehicle operation, the inner groove 12 of the outer ring is closer to the center of the vehicle and bears a greater axle load. The axle load refers to the load borne by the wheel hub bearing from the vehicle's gravity. By setting the inner groove 12 of the outer ring with variable curvature, the area of ​​the groove contact ellipse can be dynamically changed. This allows for adaptation to different contact angles according to different axial loads, thereby altering the size of the contact ellipse area and achieving dynamic adjustment of axial load capacity and friction torque.

[0041] The radius of curvature of the first curve 141 is larger than that of the second curve 142. This ensures that when the vehicle travels in a straight line, the contact point between the ball 30 and the inner raceway 12 of the outer ring is located on the first curve 141. This results in a smaller contact ellipse area between the ball 30 and the inner raceway of the outer ring in the region defined by the first curve 141, thereby reducing the frictional torque between the ball 30 and the inner raceway 12. When the vehicle turns or the wheel hits an obstacle, the contact point between the ball 30 and the inner raceway 12 shifts to the second curve 142. This configuration results in a larger contact ellipse area between the ball 30 and the inner raceway of the outer ring in the region defined by the second curve 142, thus dispersing the axial stress of the wheel hub bearing, improving its axial load-bearing capacity, and enhancing its durability.

[0042] Furthermore, compared to the inner ring unit 20, the outer ring unit 10 is more susceptible to external impacts. This application designs the inner groove 12 of the outer ring with variable curvature, which can reduce frictional torque while improving the impact resistance of the outer ring unit 10, thereby further extending the service life of the wheel hub bearing.

[0043] Furthermore, such as Figure 2 As shown, the arc length of the first curve 141 is greater than the arc length of the second curve 142. The angle α1 between the tangent of the first curve 141 near the endpoint of the outer groove 13 of the outer ring and the axis of the bearing outer ring 11 is less than 90°.

[0044] This design results in a shorter arc length for the second curve 142. When the hub bearing is subjected to only a large axial force, the ball 30 is pressed towards the area where the second curve 142 is located, increasing the contact area between the ball 30 and the inner groove 12 area of ​​the outer ring where the second curve 142 is located. This reduces stress concentration and increases the axial load capacity of the hub bearing. Under conditions where the lateral acceleration during hub turning is small and the axial load on the inner groove 12 of the outer ring is small, this design reduces the contact area between the ball 30 and the inner groove 12 area of ​​the outer ring where the first curve 141 is located, thus reducing frictional torque.

[0045] Furthermore, such as Figure 2 As shown, the first cross-sectional line 14 also includes a first straight line 143. One end of the first straight line 143 is connected to the second curve 142; the first straight line 143 is tangent to the second curve 142; the angle α2 between the first straight line 143 and the axis of the bearing outer ring 11 is less than 90°.

[0046] Since the inner groove 12 of the outer ring is formed by grinding, setting a portion of the first cross-section line 14 near the outer groove 13 of the outer ring as the first straight line 143 can reduce the machining difficulty of the area of ​​the inner groove 12 of the outer ring where the first straight line 143 is located.

[0047] Furthermore, such as Figure 2 As shown, the ratio of the length of the first straight line 143 to the arc length of the second curve 142 is between 0.15 and 0.35.

[0048] By controlling the length of the first straight line 143 within a certain range, it is possible to ensure that the length of the second curve 142 is sufficient, so that the area of ​​the inner groove 12 of the outer ring where the second curve 142 is located can meet the dynamic adjustment requirements of the axial load, while also taking into account the role of reducing the processing difficulty of the first straight line 143.

[0049] Furthermore, such as Figure 3 As shown, the second section line 25 includes a third curve 251 and a fourth curve 252. The radius of curvature of the third curve 251 is greater than that of the fourth curve 252; the end of the fourth curve 252 near the flange groove 23 is connected to the third curve 251.

[0050] This causes the ball 30 to be squeezed toward the area where the fourth curve 252 is located when the hub bearing is subjected to only a large axial force. Since the radius of curvature of the fourth curve 252 is small, the contact area between the ball 30 and the area of ​​the inner ring groove 24 where the fourth curve 252 is located is large, which reduces stress concentration and increases the axial load capacity of the hub bearing.

[0051] When the lateral acceleration is small when the wheel hub turns, the axial load of the inner groove 24 is small. Due to the large radius of curvature of the third curve 251, the contact area between the ball 30 and the inner groove 24 where the third curve 251 is located is small, which reduces the frictional torque between the ball 30 and the inner groove 24.

[0052] The radius of curvature of the third curve 251 is smaller than that of the first curve 141; the radius of curvature of the third curve 251 is larger than that of the second curve 142.

[0053] Further, refer to Figure 2 and Figure 3 The radius of curvature of the third curve 251 is smaller than that of the first curve 141; the radius of curvature of the third curve 251 is larger than that of the second curve 142.

[0054] The duration of axial load conditions on wheel hub bearings is usually short, so the impact of frictional torque is small. The radius of curvature of the second curve 142 is set to be smaller than that of the third curve 251, so that when the contact ellipse changes dynamically, the inner groove 12 area of ​​the outer ring where the second curve 142 is located can provide sufficient axial support.

[0055] Furthermore, such as Figure 3 As shown, the second section line 25 also includes a second straight line 253. One end of the second straight line 253 is connected to the fourth curve 252; the second straight line 253 is tangent to the fourth curve 252; the angle α3 between the second straight line 253 and the axis of the mating inner ring 22 is less than 90°.

[0056] Since the inner groove 24 is an arc-shaped concave surface, the grinding process takes a long time. By setting a portion of the second cross-section line 25 as the second straight line 253, the area where the second straight line 253 is located can be processed into a plane, thereby shortening the processing time and improving the processing efficiency.

[0057] In other embodiments, the ratio of the length of the second straight line 253 to the length of the second cross-section line 25 is less than a certain threshold. This setting can prevent the second straight line 253 from being too long, thereby reducing the rate of the sphere 30 climbing the shoulder on the second straight line 253 and improving processing efficiency.

[0058] Furthermore, such as Figure 3 As shown, the arc length of the third curve 251 is less than that of the fourth curve 252. This ensures sufficient contact area between the ball 30 and the inner groove 24 region containing the fourth curve 252 under large axial loads, meeting the requirements of larger axial loads. The tangent of the end of the third curve 251 near the flange groove 23 is parallel to the axis of the mating inner ring 22, preventing scratches on the ball 30 when it is pressed onto the inner groove 24.

[0059] Furthermore, such as Figure 4 As shown, the third section line 15 includes a fifth curve 151 and a sixth curve 152. The radius of curvature of the fifth curve 151 is greater than that of the sixth curve 152; the end of the fifth curve 151 near the inner groove 12 of the outer ring connects with the sixth curve 152.

[0060] The ratio of the arc length of the second curve 142 to the arc length of the first curve 141 is the first ratio; the ratio of the arc length of the sixth curve 152 to the arc length of the fifth curve 151 is the second ratio; the first ratio is greater than the second ratio.

[0061] Since the inner side of the wheel bearing installed in the inner groove 12 of the outer ring and the inner groove 24 of the inner ring bears a greater axle load, that is, bears a greater weight of the vehicle body, the first ratio is set to be greater than the second ratio, so as to meet the requirement of bearing a greater axle load on the inner side of the wheel bearing.

[0062] In other embodiments, the third section line 15 further includes a third straight line 153, the ratio of the length of the third straight line 153 to the arc length of the sixth curve 152 being in the range of 0.15 to 0.35. This ensures that the length of the sixth curve 152 is sufficient to meet the dynamic adjustment requirements of the axial load in the inner groove 12 area of ​​the outer ring where the sixth curve 152 is located, while also taking into account the role of the third straight line 153 in reducing the processing difficulty.

[0063] Furthermore, such as Figure 5 As shown, the fourth section line 26 includes a seventh curve 261 and an eighth curve 262. The radius of curvature of the seventh curve 261 is greater than that of the eighth curve 262; the end of the eighth curve 262 near the inner groove 24 connects with the seventh curve 261.

[0064] The ratio of the arc length of the fourth curve 252 to the arc length of the third curve 251 is the third ratio; the ratio of the arc length of the eighth curve 262 to the arc length of the seventh curve 261 is the fourth ratio; the third ratio is greater than the fourth ratio.

[0065] Since the inner bearings of the wheel hub bearings installed in the outer inner groove 12 and inner groove 24 bear a greater axle load, that is, bear a greater weight of the vehicle body, the third ratio is set to be greater than the fourth ratio. This can meet the requirement of bearing a greater axle load on the inner side of the wheel hub bearing.

[0066] In other embodiments, the fourth section line 26 further includes a fourth straight line 263, the ratio of the length of the fourth straight line 263 to that of the fourth section line 26 being less than a threshold. This prevents the fourth straight line 263 from being too long, thereby reducing the rate of the sphere 30 climbing over the fourth straight line 263 and improving processing efficiency.

[0067] Those skilled in the art will understand that the above embodiments are specific examples of implementing this disclosure, and in practical applications, various changes can be made in form and detail without departing from the scope of this disclosure.

Claims

1. A hub bearing with variable raceway curvature, characterized in that, The variable curvature wheel bearing includes: An outer ring unit, the outer ring unit including a bearing outer ring; the bearing outer ring has an inner outer ring groove and an outer outer ring groove inside; An inner ring unit is located inside the outer ring unit; the inner ring unit includes an inner ring flange and a mating inner ring; the mating inner ring is fixedly connected to the inner ring flange; the inner ring flange has a flange groove; the mating inner ring has an inner ring groove; the bearing outer ring, the mating inner ring, and the inner ring flange are coaxially arranged. Multiple spheres, a portion of which are located between the inner ring groove and the inner outer ring groove, and another portion of which are located between the flange groove and the outer outer ring groove; The axis of the outer ring of the bearing is located in a reference section; in the reference section, the inner groove of the outer ring has a first section line, the inner groove of the inner ring has a second section line, the outer groove of the outer ring has a third section line, and the flange groove has a fourth section line; the radii of curvature of the first section line, the second section line, the third section line, and the fourth section line are all greater than the radius of the sphere; The first cross-sectional line includes a first curve and a second curve; the radius of curvature of the first curve is greater than the radius of curvature of the second curve; the end of the first curve near the outer groove of the outer ring is connected to the second curve.

2. A wheel hub bearing with variable raceway curvature according to claim 1, characterized in that, The arc length of the first curve is greater than the arc length of the second curve; the angle between the tangent of the first curve near the end of the outer groove of the outer ring and the axis of the bearing outer ring is less than 90°.

3. A wheel hub bearing with variable raceway curvature according to claim 1, characterized in that, The first cross-sectional line further includes a first straight line; one end of the first straight line is connected to the second curve; the first straight line is tangent to the second curve; the angle between the first straight line and the axis of the outer ring of the bearing is less than 90°.

4. A wheel hub bearing with variable raceway curvature according to claim 3, characterized in that, The ratio of the length of the first straight line to the arc length of the second curve is between 0.15 and 0.

35.

5. A wheel hub bearing with variable raceway curvature according to claim 1, characterized in that, The second cross-sectional line includes a third curve and a fourth curve; the radius of curvature of the third curve is greater than that of the fourth curve; the end of the fourth curve near the flange groove is connected to the third curve.

6. A wheel hub bearing with variable raceway curvature according to claim 5, characterized in that, The radius of curvature of the third curve is smaller than that of the first curve; the radius of curvature of the third curve is larger than that of the second curve.

7. A wheel hub bearing with variable raceway curvature according to claim 5, characterized in that, The second cross-sectional line also includes a second straight line; one end of the second straight line is connected to the fourth curve; the second straight line is tangent to the fourth curve; the angle between the second straight line and the axis of the mating inner ring is less than 90°.

8. A wheel hub bearing with variable raceway curvature according to claim 5, characterized in that, The arc length of the third curve is less than that of the fourth curve; the tangent of the third curve near the end of the flange groove is parallel to the axis of the mating inner ring.

9. A wheel hub bearing with variable raceway curvature according to claim 1, characterized in that, The third cross-sectional line includes a fifth curve and a sixth curve; the radius of curvature of the fifth curve is greater than that of the sixth curve; the end of the fifth curve near the inner channel of the outer ring connects with the sixth curve; The ratio of the arc length of the second curve to the arc length of the first curve is the first ratio; the ratio of the arc length of the sixth curve to the arc length of the fifth curve is the second ratio; the first ratio is greater than the second ratio.

10. A wheel hub bearing with variable raceway curvature according to claim 5, characterized in that, The fourth cross-sectional line includes a seventh curve and an eighth curve; the radius of curvature of the seventh curve is greater than that of the eighth curve; the end of the eighth curve near the inner channel connects with the seventh curve; The ratio of the arc length of the fourth curve to the arc length of the third curve is the third ratio; the ratio of the arc length of the eighth curve to the arc length of the seventh curve is the fourth ratio; the third ratio is greater than the fourth ratio.

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