Hub bearing with variable-curvature raceway

Abstract

The invention relates to the technical field of hub bearings, in particular to a hub bearing with a variable-curvature raceway. The invention discloses a wheel hub bearing with a variable-curvature raceway. The wheel hub bearing comprises an outer ring unit, an inner ring unit and a plurality of balls, the outer ring unit comprises a bearing outer ring; an outer ring inner side channel and an outer ring outer side channel are formed in the bearing outer ring; the inner ring unit comprises an inner ring flange and a matched inner ring; the inner ring flange is provided with a flange plate channel; the matching inner ring is provided with an inner ring channel; one part of the balls are positioned between the inner ring channel and the inner side channel of the outer ring, and the other part of the balls are positioned between the flange plate channel and the outer side channel of the outer ring; wherein the axis of the bearing outer ring is located in the reference section; in the reference cross section, the outer ring inner side channel is provided with a first cross section line; the first section line comprises a first curve and a second curve; the curvature radius of the first curve is greater than that of the second curve; therefore, the problem of how to consider the friction torque and the axial bearing capacity to prolong the service life of the hub bearing is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hub bearing, in particular to a hub bearing with variable curvature raceway. BACKGROUND

[0002] The hub bearing is an important part of mechanical equipment in the categories of transportation, engineering, agriculture, etc. It is essentially a bearing unit integrating inner ring, outer ring, rolling element, retainer and sealing element. For example, in an automobile, the hub bearing connects the steering knuckle and the wheel hub, supports the weight of the vehicle body, and provides low friction and high precision guidance for the high-speed rotation of the wheel, which is a key component for realizing the coordination of vehicle load bearing and wheel rotation. The rolling element is usually installed between the grooves of the inner ring and the outer ring, allowing the inner ring and the outer ring to rotate relative to each other. The rolling element is usually a steel ball.

[0003] The friction torque between the steel ball and the groove during vehicle driving is a key factor affecting the service life of the hub bearing. When the wheel turns or hits an obstacle, it has a large axial acceleration, and the axial load capacity of the hub bearing is another key factor affecting the service life of the hub bearing. However, the groove of the hub bearing generally has a single curvature radius, and the contact area between the steel ball and the groove in the hub bearing usually does not change much during vehicle driving. If the contact area between the steel ball and the groove is designed too large, it will result in a larger friction torque, and if the contact area between the steel ball and the groove is designed too small, it will reduce the axial load capacity of the hub bearing. Therefore, how to balance the influence of friction torque and axial load capacity on the service life of the hub bearing is a technical problem that needs to be solved. SUMMARY

[0004] To solve the problem of how to balance the friction torque and the axial load capacity to improve the service life of the hub bearing, the present application provides a hub bearing with variable curvature raceway, comprising:

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

[0006] An inner ring unit, the inner ring unit is located inside the outer ring unit; the inner ring unit comprises an inner ring flange and a matching inner ring; the matching inner ring is fixedly connected with the inner ring flange; the inner ring flange has a flange groove; the matching inner ring has an inner ring groove; the bearing outer ring, the matching inner ring and the inner ring flange are coaxially arranged;

[0007] A plurality of balls, a part of the balls are located between the inner ring groove and the outer ring inner side groove, and another part of the balls are located between the flange groove and the outer ring outer side groove;

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

[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 first curve is connected to the second curve near one end of the outer ring outer raceway.

[0010] In some embodiments, the arc length of the first curve is greater than the arc length of the second curve; the tangent line of the first curve near the end of the outer ring outer raceway has an angle of less than 90° with the axis of the bearing outer ring.

[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; the first straight line has an angle of less than 90° with the axis of the bearing outer ring.

[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 fourth curve is connected to the third curve near one end of the flange raceway.

[0014] In some embodiments, the radius of curvature of the third curve is less than the radius of curvature of the first curve; the radius of curvature of the third curve is greater than the radius of curvature 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; the second straight line has an angle of less than 90° with the axis of the mating inner ring.

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

[0017] In some embodiments, the third cross-sectional line comprises a fifth curve and a sixth curve; the fifth curve has a larger radius of curvature than the sixth curve; the fifth curve connects to the sixth curve near one end of the outer-ring inner-side groove;

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

[0019] In some embodiments, the fourth cross-sectional line comprises a seventh curve and an eighth curve; the seventh curve has a larger radius of curvature than the eighth curve; the eighth curve connects to the seventh curve near one end of the inner-ring groove;

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

[0021] To solve the problem of how to balance the friction torque and the axial load capacity to improve the service life of the hub bearing, the present application has the following advantages:

[0022] The first cross-sectional line of the inner side channel of the outer ring is provided as a first curve and a second curve in the application, and the curvature radius of the first curve is greater than that of the second curve, and the first curve is connected to the second curve near one end of the outer side channel of the outer ring. That is, the curvature radius of the inner side channel of the outer ring is designed as a variable curvature design that changes along the axial direction of the hub bearing, and the curvature radius of the inner side channel of the outer ring gradually decreases in the direction close to the outer side channel of the outer ring. The driving state of the vehicle for most of the time is straight driving, and the first curve area of the inner side channel of the outer ring is in contact with the ball when straight driving, and the contact area is small, thereby reducing the friction torque during long-time driving. When the vehicle is turning or the wheel hits an obstacle, the steel ball is in contact with the area of the second curve of the inner side channel of the outer ring, and the contact area is large, thereby improving the axial bearing capacity of the inner side channel of the outer ring of the hub bearing. Therefore, the variable curvature design of the inner side channel of the outer ring can realize the dynamic change of the contact area between the ball and the channel under different driving conditions of the vehicle, thereby balancing the friction torque and the axial bearing capacity, and improving the service life of the hub bearing. The channel on the inner side of the hub bearing is closer to the middle of the vehicle and bears greater axial load. The variable curvature design of the inner side channel of the outer ring in the application can greatly improve the dynamic change range of the contact area between the steel ball and the channel, thereby maximizing the service life of the hub bearing. In addition, compared with the inner ring unit, the outer ring unit is more susceptible to external impact, and the variable curvature design of the inner side channel of the outer ring can reduce the friction torque while improving the impact resistance of the outer ring unit. Therefore, the service life of the hub bearing is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A cross-sectional view of a hub bearing with a variable curvature raceway according to an embodiment is shown;

[0024] Figure 2 A brief schematic view of a first cross-sectional line in Figure 1 is shown;

[0025] Figure 3 A brief schematic view of a second cross-sectional line in Figure 1 is shown;

[0026] Figure 4 A brief schematic view of a third cross-sectional line in Figure 1 is shown;

[0027] Figure 5 A brief schematic view of a fourth cross-sectional line in Figure 1 is shown.

[0028] Reference signs: 10 outer ring unit; 11 bearing outer ring; 12 outer ring inner side groove; 13 outer ring outer side groove; 14 first cross-sectional line; 141 first curve; 142 second curve; 143 first straight line; 15 third cross-sectional 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 disc groove; 24 inner ring groove; 25 second cross-sectional line; 251 third curve; 252 fourth curve; 253 second straight line; 26 fourth cross-sectional line; 261 seventh curve; 262 eighth curve; 263 fourth straight line; 30 ball. DETAILED DESCRIPTION

[0029] The present disclosure will now be discussed with reference to several exemplary embodiments. It should be appreciated that these embodiments are discussed only to better illustrate the present disclosure and are not intended to limit the scope of the present disclosure in any way.

[0030] As used herein, the term "includes" and its variants are to be read as open-ended terms that mean "including, but not limited to." The term "based on" is to be construed as "based at least in part on." The terms "one embodiment" and "an embodiment" are to be read as "at least one embodiment." The term "another embodiment" is to be read as "at least one other embodiment." The terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "vertical," "horizontal," "lateral," "longitudinal," and similar terms are used for description only and not intended to convey an intended orientation of the device, component, or element described. These terms are used primarily just to better describe the application and its embodiments and do not limit the scope of the indicated device, component, or element to a particular orientation, unless otherwise specified. Also, the terms "mount," "set," "provided with," "connected," "linked," should be given a broad interpretation. For example, it can be fixed connection, detachable connection, or integral structure; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through an intermediate medium; or it can be internal connection between two devices, components, or elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. In addition, the terms "first," "second," and the like are primarily used to distinguish different devices, components, or elements (the specific types and structures of which can be the same or different), and are not intended to indicate or imply relative importance and quantity of the indicated devices, components, or elements. Unless otherwise specified, the meaning of "multiple" is two or more.

[0031] The hub bearing is an important part of mechanical equipment in the categories of transportation, engineering, agriculture, etc. It is a bearing unit composed of an inner ring, an outer ring, rolling elements, a retainer, and a sealing element. When installed in a vehicle, the hub bearing serves to connect the steering knuckle and the hub of the vehicle. The rolling elements are usually installed between the grooves of the inner ring and the outer ring, allowing the inner ring and the outer ring to rotate relative to each other. Since the curvature radius of a single groove is usually a fixed value, the friction torque of the hub bearing is large during vehicle driving, and the axial load capacity needs to be improved. To solve the problem of how to balance the friction torque and the axial load capacity to improve the service life of the hub bearing, the present application provides a hub bearing with variable curvature raceways.

[0032] Embodiment One:

[0033] In this embodiment, as Figure 1As shown, a kind of curvature of raceway hub bearing includes outer ring unit 10, inner ring unit 20, multiple balls 30.

[0034] Outer ring unit 10 includes bearing outer ring 11;The inside of bearing outer ring 11 has two channels, respectively, outer ring inner side channel 12 and outer ring outer side channel 13;

[0035] Inner ring unit 20 is located in the inside of outer ring unit 10;Inner ring unit 20 includes inner ring flange 21 and matching inner ring 22;Matching inner ring 22 is fixedly connected with inner ring flange 21;The interference fit of matching inner ring 22 and inner ring flange 21 can be carried out, and then the edge of matching inner ring 22 is crimped and fixedly positioned with inner ring flange 21 after alignment.Inner ring flange 21 has flange channel 23;Matching inner ring 22 has inner ring channel 24;Bearing outer ring 11, matching inner ring 22 and inner ring flange 21 are coaxially arranged;

[0036] A part of balls 30 is located between inner ring channel 24 and outer ring inner side channel 12, and another part of balls 30 is located between flange channel 23 and outer ring outer side channel 13;In this way, balls 30 can be installed between outer ring unit 10 and inner ring unit 20, and outer ring unit 10 and inner ring unit 20 can rotate coaxially relative to each other.

[0037] When hub bearing is installed on vehicle or other transport tools, outer ring unit 10 is fixedly connected with steering knuckle or axle head of vehicle, steering knuckle or axle head is connected with transmission shaft, and inner ring unit 20 is fixedly connected with hub of vehicle.In this way, the power of transmission shaft can be transmitted to hub, and then drive the rotation of wheel, at this time, hub bearing, hub and wheel are coaxial.

[0038] Wherein, the axis of bearing outer ring 11 is located in reference section;In reference section, outer ring inner side channel 12 has first section line 14, inner ring channel 24 has second section line 25, outer ring outer side channel 13 has third section line 15, and flange channel 23 has fourth section line 26;The curvature radius of first section line 14, second section line 25, third section line 15 and fourth section line 26 is all greater than the radius of ball 30;In this way, ball 30 and outer ring inner side channel 12, inner ring channel 24, outer ring outer side channel 13 and flange channel 23 are all point contact, but after the installation of hub bearing is completed, because ball 30 and outer ring unit 10 and inner ring unit 20 are all extruded, ball 30 and outer ring inner side channel 12, inner ring channel 24, outer ring outer side channel 13 and flange channel 23 form elliptical contact surface, which is called contact ellipse.

[0039] As shown in the figure, 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] In this way, the arc length of the second curve 142 is shorter, so that when the hub bearing only bears a large axial force, the ball 30 is pressed to the area where the second curve 142 is located, the contact area between the ball 30 and the area of the outer ring inner raceway 12 where the second curve 142 is located is increased, the stress concentration is reduced, and the axial load carrying capacity of the hub bearing is increased. When the lateral acceleration of the hub during cornering is small, the axial load of the outer ring inner raceway 12 is small, and in this way, the contact area between the ball 30 and the area of the outer ring inner raceway 12 where the first curve 141 is located is reduced, and the friction torque is reduced.

[0045] Further, as shown in Figure 2 The first straight line 143 is connected to the second curve 142 at one end, is tangent to the second curve 142, and the included angle α2 between the first straight line 143 and the axis of the bearing outer ring 11 is less than 90°.

[0046] Since the outer ring inner raceway 12 is machined by grinding, setting the part of the first cross-sectional line 14 close to the outer ring outer raceway 13 as the first straight line 143 can reduce the machining difficulty of the area of the outer ring inner raceway 12 where the first straight line 143 is located.

[0047] Further, as shown in Figure 2 The ratio of the length of the first straight line 143 to the arc length of the second curve 142 is 0.15-0.35.

[0048] In this way, the length of the first straight line 143 is controlled within a certain range, which can ensure that the length of the second curve 142 is sufficient to meet the dynamic adjustment requirements of the axial load in the area of the outer ring inner raceway 12 where the second curve 142 is located, and also take into account the role of the first straight line 143 in reducing machining difficulty.

[0049] Further, as shown in Figure 3 The second cross-sectional line 25 includes a third curve 251 and a fourth curve 252. The radius of curvature of the third curve 251 is greater than the radius of curvature of the fourth curve 252, and the end of the fourth curve 252 close to the flange raceway 23 is connected to the third curve 251.

[0050] In this way, when the hub bearing only bears a large axial force, the ball 30 is pressed to the area where the fourth curve 252 is located, and 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 raceway 24 where the fourth curve 252 is located is large, the stress concentration is reduced, and the axial load carrying capacity of the hub bearing is increased.

[0051] When the lateral acceleration of the hub is small, the axial load of the inner ring raceway 24 is small, and since the radius of curvature of the third curve 251 is large, the contact area of the ball 30 with the region of the inner ring raceway 24 where the third curve 251 is located is small, thereby reducing the friction torque between the ball 30 and the inner ring raceway 24.

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

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

[0054] The duration of the working condition of the hub bearing under a large axial load is usually short, and thus the influence of the friction torque is small. Therefore, the radius of curvature of the second curve 142 is set to be smaller than the radius of curvature of the third curve 251, so that when the contact ellipse changes dynamically, the region of the inner ring raceway 12 where the second curve 142 is located can provide sufficient axial support.

[0055] Further, as shown in Figure 3 The second straight line 253 is connected to the fourth curve 252 at one end; the second straight line 253 is tangent to the fourth curve 252; and the angle α3 between the second straight line 253 and the axis of the mating inner ring 22 is smaller than 90°.

[0056] Since the inner ring raceway 24 is an arc-shaped concave surface, the grinding processing time is long. Therefore, by setting a part of the second cross-sectional line 25 as the second straight line 253, the region where the second straight line 253 is located can be processed as a flat surface, thereby shortening the processing time and improving the processing efficiency.

[0057] In some other embodiments, the ratio of the length of the second straight line 253 to the length of the second cross-sectional line 25 is smaller than a certain threshold value. In this way, the second straight line 253 is prevented from being too long, thereby reducing the rate of climbing the shoulder of the ball 30 on the second straight line 253 and improving the processing efficiency.

[0058] Further, as shown in Figure 3 The arc length of the third curve 251 is smaller than the arc length of the fourth curve 252. In this way, when the axial load is large and the ball 30 is pressed against the region where the fourth curve 252 is located, the ball 30 and the region of the inner ring raceway 24 where the fourth curve 252 is located have sufficient contact area, thereby meeting the requirement of a large axial load. The tangent line of the end of the third curve 251 close to the flange raceway 23 is parallel to the axis of the mating inner ring 22, thereby preventing the ball 30 from being scratched when being pressed onto the inner ring raceway 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] It is understood by those of ordinary skill in the art that the above-mentioned embodiments are specific cases for implementing the present disclosure, and in actual applications, various changes can be made in form and details without departing from the scope of the present disclosure.

Claims

1. A variable-crowned raceway hub bearing, characterized by, The variable-curvature raceway hub bearing comprises: an outer ring unit comprising a bearing outer ring; the bearing outer ring has an inner portion with an outer ring inner raceway and an outer ring outer raceway; an inner ring unit located inside the outer ring unit; the inner ring unit comprises an inner ring flange and a mating inner ring; the mating inner ring is fixedly connected with the inner ring flange; the inner ring flange has a flange disc raceway thereon; the mating inner ring has an inner ring raceway thereon; the bearing outer ring, the mating inner ring and the inner ring flange are coaxially arranged; a plurality of balls, a part of the balls being located between the inner ring raceway and the outer ring inner raceway, and another part of the balls being located between the flange disc raceway and the outer ring outer raceway; wherein the axis of the bearing outer ring is located in a reference cross section; in the reference cross section, the outer ring inner raceway has a first cross section line, the inner ring raceway has a second cross section line, the outer ring outer raceway has a third cross section line, and the flange disc raceway has a fourth cross section line; the first cross section line, the second cross section line, the third cross section line and the fourth cross section line all have a curvature radius greater than the radius of the balls; the first cross section line comprises a first curve and a second curve; the curvature radius of the first curve is greater than the curvature radius of the second curve; the first curve is connected with the second curve at one end close to the outer ring outer raceway.

2. The variable-curvature raceway hub bearing according to claim 1, wherein the arc length of the first curve is greater than the arc length of the second curve; the tangent line of the end point of the first curve close to the outer ring outer raceway has an angle less than 90° with the axis of the bearing outer ring.

3. The variable-curvature raceway hub bearing according to claim 1, wherein the first cross section line further comprises a first straight line; one end of the first straight line is connected with the second curve; the first straight line is tangent to the second curve; the first straight line has an angle less than 90° with the axis of the bearing outer ring.

4. The variable-curvature raceway hub bearing according to claim 3, wherein 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. The variable-curvature raceway hub bearing according to claim 1, wherein the second cross section line comprises a third curve and a fourth curve; the curvature radius of the third curve is greater than the curvature radius of the fourth curve; the fourth curve is connected with the third curve at one end close to the flange disc raceway.

6. The variable-curvature raceway hub bearing according to claim 5, wherein the curvature radius of the third curve is less than the curvature radius of the first curve; the curvature radius of the third curve is greater than the curvature radius of the second curve.

7. The variable-curvature raceway hub bearing according to claim 5, wherein the second cross section line further comprises a second straight line; one end of the second straight line is connected with the fourth curve; the second straight line is tangent to the fourth curve; the second straight line has an angle less than 90° with the axis of the mating inner ring.

8. The variable curvature track hub bearing of claim 5, wherein: an arc length of the third curve is less than an arc length of the fourth curve; and a tangent of the third curve proximate an end of the flange channel is parallel to the axis of the mating inner ring.

9. The variable curvature track hub bearing of claim 1, wherein: the third cross-sectional line includes a fifth curve and a sixth curve; a radius of curvature of the fifth curve is greater than a radius of curvature of the sixth curve; and the fifth curve merges with the sixth curve proximate an end of the outer ring inner channel; a ratio of an arc length of the second curve to an arc length of the first curve is a first ratio; a ratio of an arc length of the sixth curve to an arc length of the fifth curve is a second ratio; and the first ratio is greater than the second ratio.

10. The variable curvature track hub bearing of claim 5, wherein: the fourth cross-sectional line includes a seventh curve and an eighth curve; a radius of curvature of the seventh curve is greater than a radius of curvature of the eighth curve; and the eighth curve merges with the seventh curve proximate an end of the inner ring channel; a ratio of an arc length of the fourth curve to an arc length of the third curve is a third ratio; a ratio of an arc length of the eighth curve to an arc length of the seventh curve is a fourth ratio; and the third ratio is greater than the fourth ratio.

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