Wheel bearing unit with radial and axial displacement limiters

Abstract

A hub bearing unit includes an inner ring having an inboard and an outboard axial end and a bearing inner raceway on the outer surface of the inner ring. An outer ring surrounding the inner ring has an inboard and an outboard axial end and a bearing outer raceway provided on the outer surface of the outer ring. One of the inner and outer rings is connected to a wheel so as to be rotatable about an axis, and the other of the inner and outer rings is fixedly connected to a vehicle frame. A plurality of rolling elements are capable of rolling on the inner and outer raceways. One of the bearing rings radially extends a displacement limiter, and the limiter has a frustoconical stop surface that forms a radial gap with a surface of the other bearing ring. When one bearing ring is displaced radially and / or axially relative to the other bearing ring, the stop surface of the limiter engages with the surface of the other bearing ring for preventing Brinell impact from occurring on the bearing raceway. In a preferred case, the position limiter is axially located between the rolling element and the inboard end of the bearing ring.

Description

Field of the Invention

[0001] The invention relates to a bearing, in particular to a wheel hub unit. Background Art

[0002] A wheel hub unit is a known product and is typically used to rotatably connect a wheel to a vehicle frame. The wheel hub unit includes an inner ring, an outer ring, and rolling elements disposed between the inner and outer rings. Here, the wheel is assembled on one bearing ring, and the other bearing ring is connected to the vehicle frame through a shaft, a suspension assembly, or a steering mechanism. When the wheel is subjected to a lateral impact of sufficient strength, the impact may cause the bearing ring connected to the wheel to bend, resulting in a relative displacement between the inner and outer rings in the radial and axial directions. This relative displacement may cause the rolling elements to impact the raceways with sufficient force, resulting in indentations on the raceway surfaces. These indentations or "brinelling" may have an adverse effect on the operation of the bearing, leading to premature wear and failure of the bearing raceways. Summary of the Invention

[0003] On the one hand, the present invention provides a wheel hub bearing unit for rotatably connecting a wheel to a vehicle frame. The wheel hub bearing unit includes an inner ring having an inboard axial end, an outboard axial end, an outer circumferential surface, and at least one bearing inner ring raceway provided on the outer circumferential surface. The outer ring is disposed around the inner ring and has an inboard axial end, an outboard axial end, an inner circumferential surface, and at least one bearing outer ring raceway provided on the inner circumferential surface. One of the inner and outer rings is connected to the wheel and is thus capable of rotating about a central axis, and the other of the inner and outer rings is connected to the vehicle frame. Rolling elements are capable of rolling on the inner and outer ring raceways to rotatably connect the inner and outer rings together. In addition, a displacement limiter extends radially from the outer surface of the inner ring or the inner surface of the outer ring. The limiter has a generally frustoconical stop surface that is radially spaced apart from the inner surface of the outer ring or the outer surface of the inner ring. When one of the inner and outer rings is displaced relative to the other of the inner and outer rings in the radial or axial direction, the stop surface engages with the outer ring or the inner ring.

[0004] On the other hand, the present invention also provides a hub bearing unit for rotatably connecting a wheel to a vehicle frame. The hub bearing unit includes an inner ring connected to the wheel and capable of rotating about a central axis. The inner ring has an inner axially end, an outer axially end, an outer circumferential surface, and at least one inner ring raceway provided on the outer circumferential surface. An outer ring is connected to the vehicle frame and disposed around the inner ring, having an inner axially end, an outer axially end, an inner circumferential surface, at least one outer ring raceway provided on the inner circumferential surface of the outer ring, and a recessed generally frustoconical engagement surface section located on the inner circumferential surface. A plurality of rolling elements can roll on the inner and outer ring raceways for rotatably connecting the inner and outer rings together. A displacement limiter extends radially outward from the outer circumferential surface of the inner ring and has a generally frustoconical protruding stop surface that forms a radial and axial spacing with the engagement surface section of the outer ring. When the inner ring is displaced radially or axially relative to the outer ring, the stop surface contacts the engagement surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The above general description of the present invention and the following detailed description of the preferred embodiments will be better understood by reading in conjunction with the following drawings. For the purpose of illustrating the present invention, the currently preferred specific embodiments are shown in the schematic diagrams. However, it should be understood that the present invention is not limited to the specific designs and means shown in the drawings. In the following drawings:

[0006] Figure 1 is an axial sectional view of the hub bearing unit with axial and radial displacement limiters according to the present invention;

[0007] Figure 2 is Figure 1 an enlarged view of the upper half;

[0008] Figure 3 is Figure 2 a further partial enlarged view showing the displacement limiter spaced from the engagement surface of the outer ring;

[0009] Figure 4 is Figure 3 another partial enlarged view of the hub bearing unit in showing the displacement limiter touching the engagement surface of the bearing ring;

[0010] Figure 5 is Figure 3 a highly magnified partial enlarged view of ; and

[0011] Figure 6It is an axial sectional view of a candidate structure of a hub bearing unit, showing that a displacement limiter connected to the outer ring can touch and combine with the inner ring. Detailed implementation mode

[0012] In the following description, the use of certain terms is for convenience only and not for restrictive purposes. The terms "inner", "inward", "outer", and "outward" respectively refer to the directions pointing to or away from the specified center line or geometric center of the described component, and their specific meanings are obvious from the context description. In addition, as described in the text, the respective meanings of the terms "connected" and "joined" include both direct connection where no other components intervene between two components and indirect connection where one or more other components intervene between two components. The terms include the above specific terms, their derivatives, and words with similar meanings.

[0013] Now refer to the attached drawings in detail, where like reference numerals are used throughout to denote like components. Figures 1 to 6 As shown, the hub bearing unit 10 preferably connects the wheel 1 to the vehicle frame 2 in a rotatable manner through a steering mechanism or a suspension, or through a powertrain (not shown), as Figure 1 shown. The hub bearing unit 10 basically includes an inner ring 12, an outer ring 14 disposed around the inner ring 12, at least several or a row of rolling elements 16 disposed between the inner and outer rings 12 and 14, and a displacement limiter 18 designed to limit the relative displacement of the inner and outer rings 12 and 14 in the radial and axial directions. Specifically, the inner ring 12 is generally cylindrical, having an axial end 12a on the inboard side (inside the vehicle), an axial end 12b on the outboard side (outside the vehicle), an outer circumferential surface 13, and at least one row of inner raceways 22 provided on the outer circumferential surface 13. The inner ring 12 preferably has a central hole 24 designed to accommodate a shaft 3 connected to the vehicle frame 2. The outer ring 14 is generally tubular, having an inboard axial end 14a, an outboard axial end 14b, an inner circumferential surface 15, and at least one row of outer raceways 26 provided on the inner circumferential surface 15 of the outer ring.

[0014] As will be discussed in detail later, one of the inner ring 12 and the outer ring 14 is connected to the wheel 1 so as to be able to rotate around the central axis A Crotates, while the other of the inner ring 12 and the outer ring 14 is connected to the vehicle frame 2 in a fixed or non-rotating manner. In addition, a plurality of rollers 16 can roll on the inner ring raceway 22 and the outer ring raceway 26 simultaneously so as to rotatably connect the inner ring and the outer rings 12, 14 together. In a preferred case, the rolling elements 16 are generally spherical rollers, but as an alternative, they can also be cylindrical rollers, conical rollers, needle rollers or any other type of rolling elements. In a preferred case, the inner ring 12 and the outer ring 14 are made of a metallic material, such as high carbon steel or medium carbon steel, and the rolling elements 16 are either made of a metallic material, such as chrome steel, or formed of a ceramic material, such as alumina.

[0015] In addition, the displacement limiter 18 is formed either as a single annular body 30 or as a plurality of arcuate segments (not shown), as will be described in detail later. Regardless of which structure is adopted, the limiter 18 extends radially either from the outer surface 13 of the inner ring or from the inner surface 15 of the outer ring, and has a frustoconical stop surface 19 that is radially spaced from the inner surface 15 of the outer ring or the outer surface 13 of the inner ring. In other words, when the limiter 18 extends radially outward from the outer surface 13 of the inner ring 12, the stop surface 19 is spaced (spaced apart) from the inner surface 15 of the outer ring 14 or the inner circumferential surface of a component (not shown) provided on the inner surface 15 of the outer ring in the radial inner side. Conversely, when the limiter 18 extends radially inward from the inner surface 15 of the outer ring 14, the stop surface 19 is radially spaced from the outer surface 13 of the inner ring 12 or the outer circumferential surface of a component (not shown) located on the outer surface 13 of the inner ring in the radial outer side.

[0016] In either case, when one of the inner and outer rings 12, 14 is displaced relative to the other of the inner and outer rings 12, 14 radially and / or axially, the limiter 18 is arranged to contact the inner surface 15 of the outer ring or the outer surface 13 of the inner ring directly or indirectly (i.e., through a connecting member) with its frustoconical stop surface 19, as Figure 4 shown. In this way, the displacement limiter 18 is functionally used to "limit" the overall potential relative displacement between the bearing rings 12 and 14 radially and axially, especially when the wheel 1 experiences a bending event (referring to the bending of the bearing rings connected to the wheel caused by the aforementioned lateral impact), it can reduce or eliminate any potential impact damage to the bearing raceways 22 and 26, as will be elaborated in detail later. After describing the above basic components and functions in detail, these and other components of the hub bearing unit 10 will be described in detail below.

[0017] In a preferred case, the frustoconical stop surface 19 can touch ( / contact) the joint surface ( / bonding surface) 20 formed on the outer ring 14 or the inner ring 12 in a special way (such as machining, forging, stamping, etc.), and the joint surface 20 extends both axially and radially with respect to the central axis A C At the most preferred case, the joint surface 20 is frustoconical, complementary to the stop surface 19, so that where the stop surface 19 is generally convex, the joint surface 20 is generally concave, or vice versa. However, the joint surface 20 can also be provided by a curved surface on one of the bearing rings 12, 14, or even a relatively sharp "corner" (not shown in the figure), and can contact the stop surface 19 of the limiter 18 on the other bearing ring 14, 12 to limit axial and radial displacements. In addition, the joint surface 20 can also be provided by a part of the inner surface 15 of the outer ring 14, a part of the outer surface 13 of the inner ring 12, or the circumferential surface or arc surface of a member assembled on one of the bearing rings 12, 14. For example, such an independent member can be a raceway insert 62 (described later), a rigid seal (not shown), etc.

[0018] Referring to Figure 3 、 5 and 6, by adopting the more preferable complementary surfaces 19, 20, the stop surface 19 preferably defines a first angle θ1 with respect to the central axis A C The joint surface 20 preferably defines a second angle θ2 with respect to the central axis A C In the most preferred case, the first angle θ1 and the second angle θ2 have approximately equal angular values, so that the two frustoconical surfaces 19 and 20 are approximately parallel in any axial cross-section (i.e., the cross-section containing the central axis A C ). In this way, an angled annular control gap GC is defined between the stop surface 19 and the joint surface 20, and the gap is preferably set such that the shortest distance value between the two surfaces 19, 20 is less than 0.30 mm.

[0019] The displacement limiter 18 is set by this structure, that is, by changing its radial dimension or diameter dimension, determining its position, and selecting the respective angular values of the first angle θ1 and the second angle θ2, so that the control gap GC has both a predetermined radial length L R and a predetermined axial length L A , as Figure 5 shown. In this way, the radial relative displacement between the inner ring 12 and the outer ring 14 is limited within the radial length L of the control gap R , and the axial relative displacement between the two bearing rings 12 and 14 is limited within the axial length L of the control gap A .

[0020] In a preferred case, for reasons discussed later, the radial length value L of the control gap GC R is approximately between 0.10 and 0.31 millimeters, and the axial length value L of the control gap GC A is approximately between 0.57 and 1.73 millimeters. In addition, the angular values of the first angle θ1 and the second angle θ2 are preferably approximately between 10 degrees (10°) and 80 degrees (80°), and preferably around approximately 75 degrees (75°), so as to give the two gap lengths L R and L A an ideal relative amplitude. Obviously, an angular value of 45 degrees can provide approximately equal radial length L R and axial length L A . In addition, by adjusting the angular values of the first angle θ1 and the second angle θ2, the relative radial length L R and axial length L A of the control gap GC can also be changed, that is, while reducing the radial length L R , increasing the axial length L A , or vice versa, depending on the maximum ideal relative radial and axial displacements allowed between the inner ring 12 and the outer ring 14.

[0021] In any case, the control gap GC is sized as described above so that, in the normal operating state of the vehicle, the bearing ring 12 or 14 connected to the wheel 1 can rotate freely about the central axis A C . However, when an impact event (for example, the wheel hitting a curb or getting stuck in a pothole, etc.) occurs, since the movable bearing ring 12 or 14 touches the displacement limiter 18, the displacement of the bearing ring 12 or 14 connected to the wheel relative to the other bearing ring 14 or 12 in the radial and axial directions is prevented from exceeding the radial length L R and axial length L A of the control gap GC. As mentioned before, excessive displacement of one bearing ring 12 or 14 relative to the other bearing ring 14 or 12 may cause the rolling elements 16 to impact the outer surfaces 22a, 26a of the raceways 22, 26 with sufficient force, causing the outer surfaces 22a, 26a to dent. This mechanism of forming dents is called "brinelling". In typical cases, brinelling causes excessive vibration or chattering of the rolling elements 16 and accelerates the wear of the raceway surfaces 22a, 26a, resulting in galling and / or cracking of the bearing material, or flaking off.

[0022] Thus, by restricting the relative displacement of the inner ring 12 and the outer ring 14 in the radial and axial directions, the displacement limiter 18 functions as an "anti-brinelling" device. Specifically, the preferred axial and radial lengths L R 、L A have been determined to prevent radial and axial displacements whose amplitudes may cause brinelling, while allowing the bearing rings 12, 14 to rotate freely relative to each other during normal vehicle operation.

[0023] See Figure 1 and 2 , the displacement limiter 18 is preferably axially located between a plurality of rolling elements 16 (the rolling elements 16 preferably form an inboard rolling element row 17A as described hereinafter) and the respective inboard axial ends 12a, 14a of the inner and outer rings 12 and 14. In this way, the limiter 18 can more effectively restrict the relative displacement of the inboard axial end 12a of the inner ring 12 and the inboard axial end 14a of the outer ring 14 in the axial and radial directions, thereby better maintaining the integrity of the respective surfaces of the inboard inner and outer ring raceways 23A and 27A, as described hereinafter.

[0024] Now see Figure 2 、 3 and 6, the displacement limiter 18 is preferably formed as a generally annular single body 30 having axially opposite ends 30a, 30b and inner and outer radial ends 32A, 32B, with one of the radial ends 32A or 32B providing a frustoconical stop surface 19. The stop surface 19 is substantially continuous about the central axis A C or forms a plurality of arcuate surface sections (i.e., separated by radial depressions) spaced circumferentially about the central axis A C . As an alternative, the displacement limiter comprises a plurality of arcuate body segments (not shown) circumferentially distributed about the central axis A C each having axially opposite (two) ends and inner and outer radial ends, with one of the radial ends having an arcuate frustoconical surface portion that forms part of the frustoconical stop surface (i.e., the plurality of arcuate surface sections together provide the stop surface). In either case, the single body 30 or the plurality of arcuate body segments is made of a generally rigid material, preferably a metallic material such as low-carbon steel, or may be made of any suitable material such as a rigid polymeric material or a ceramic material.

[0025] Regardless of the structure adopted, the inner radial end 32A of the displacement limiter 18 is preferably connected to or integrally formed with the inner ring 12, and its outer radial end 32B is spaced from the inner surface 15 of the outer ring 14 radially inwardly, thereby providing a frustoconical stop surface 19, as Figures 1 to 5 shown. In a most preferred case, the limiter 18 is provided by a washer-like body 30 having an inner circumferential surface 33 that frictionally engages (i.e., press-fits) with the outer surface 13 of the inner ring 12 and can be removably connected to the inner ring 12. As an alternative, as Figure 6 shown, the outer radial end 32B of the displacement limiter 18 is connected to or integrally formed with the outer ring 14, and the inner radial end 32A or the end of the arcuate body segment is spaced from the outer surface 13 of the inner ring 12 radially outwardly, thereby providing a frustoconical stop surface 19.

[0026] See Figure 1 and 2 , the hub unit 10 is preferably a double-row bearing 11, including two sets of inner and outer ring raceways and two sets of rolling elements. Specifically, the inner ring 12 has a first inner ring raceway 23A on the inner side of the cabin and a second inner ring raceway 23B on the outer side of the cabin that is axially spaced from the first inner ring raceway 23A. Similarly, the outer ring 14 has a first raceway 27A on the inner side of the cabin and a second outer ring raceway 27B on the outer side of the cabin that is axially spaced from the first outer ring raceway 27A. In addition, a first number of rolling elements or the first row of rolling elements 17A of the rolling elements 16 are arranged between the first inner ring raceway 23A and the first outer ring raceway 27A and can roll between these two raceways; a second number of rolling elements or the second row of rolling elements 17B of the rolling elements 16 are arranged between the second inner ring raceway 23B and the second outer ring raceway 27B and can roll between these two raceways.

[0027] With the double-row bearing 11 in the preferred case, the displacement limiter 18 can also, as an alternative, be arranged between the double-row rolling elements 17A and 17B, or even outside the second row of rolling elements 17B of the rolling elements 16 on the outer side of the cabin. In addition, the double-row hub unit 10 preferably further includes first and second cages 60A, 60B for relatively limiting and holding the respective rows of rolling elements 17A, 17B of the rolling elements 16 and seals 61A and 61B on the inner and outer sides of the cabin, and the seals 61A and 61B are used to hold lubricant (such as grease) within the rolling elements 16 and resist contaminants. Although the double-row bearing is more preferable, as an alternative, the hub unit 10 can also be formed as a hub unit (not shown) that only includes a single row of rolling elements 16 for specific uses.

[0028] Still referring to Figure 1 and2 , the inner ring 12 preferably includes an annular insert 62 seated in an annular groove 64 extending inwardly on the outer surface 13 of the inner ring and held by a flange or rolled end 64 formed at the inner end 12a of the inner ring hub. The insert 62 has an outer circumferential surface 63 for providing a first raceway 23A on the inner side of the hub and a portion 13a of the outer surface 13 of the inner ring. Preferably, the displacement limiter 18 is disposed around the portion 13a of the outer surface 63 of the insert, so as to form an axial spacing from the inner ring raceway 23A on the side of the inner end 12a of the inner ring hub and is preferably held on the insert 62 by friction. As an alternative, the displacement limiter 18 may also be integrally formed with the insert 62 and extend radially outwardly from the outer surface 63 of the insert (this structure is not shown). In addition, the second inner ring raceway 23B on the outer side of the hub is preferably directly formed on the outer surface 13 of the inner ring 12, and the first and second outer ring raceways 27A, 27B are directly formed on the inner surface 15 of the outer ring 14. However, as an alternative, any one of the second inner ring raceway 23B, the outer ring raceways 27, 27B, or both of the outer ring raceways 27, 27B may be provided by a suitable annular insert (not shown), and / or the first inner ring raceway 23A may also, as an alternative, be directly formed on the outer surface 13 of the inner ring 12.

[0029] In some currently preferred structures, as described above, the inner ring 12 is a hub, or a "flanged inner ring", including a flange 66 extending radially outwardly from the outer end 12b of the inner ring hub. The flange 66 is preferably connected to the wheel 1 by a plurality of bolts 67, so as to assemble the wheel 1 on the hub unit 10. As described above, in such a structure, the inner ring 1 can rotate about the central axis A C and, preferably, the central hole 24 accommodates the end of the vehicle rotating shaft 3 ( Figure 1 ). In addition, the outer ring 14 is preferably also connected to the steering mechanism or the suspension by a central flange 68 extending radially outwardly along its outer circumferential surface 70.

[0030] However, as an alternative, the hub unit 10 may also be formed such that its outer ring 14 serves as a hub, so that a flange extending radially outwardly (not shown) is formed at the outer end 14b of the outer ring hub of the outer ring 14. Such an outer ring flange can be connected to the wheel 1, so that the outer ring 14 can rotate about the central axis A C and rotate. In addition, in such a candidate structure, the inner ring 12 is preferably assembled on a stub shaft (not shown) connected to the steering mechanism or the suspension.

[0031] Those skilled in the art will understand that the above specific embodiments can be changed and modified without departing from the broad inventive concept of the present invention. Therefore, it should be understood that the present invention is not limited by the specific embodiments disclosed, but rather should be understood to include various changes within the spirit and scope of the present invention generally defined by the appended claims.

Claims

1. A wheel hub bearing unit for rotatably connecting a wheel to a vehicle frame, the wheel hub bearing unit comprising: an inner ring, the inner ring having an inner axial end, an outer axial end, an outer circumferential surface, and at least one bearing inner ring raceway disposed on the outer circumferential surface; an outer ring disposed around the inner ring, the outer ring having an inner axial end, an outer axial end, an inner circumferential surface, and at least one bearing outer ring raceway disposed on the inner circumferential surface, one of the inner ring and the outer ring being connected to the wheel so as to be rotatable about the central axis, and the other of the inner ring and the outer ring being connected to the vehicle frame; a plurality of rolling elements, each of which is capable of rolling on the inner ring raceway and the outer ring raceway, thereby rotatably connecting the inner ring and the outer ring; as well as A displacement limiter extending radially from the outer surface of the inner ring or the inner surface of the outer ring, having a frustoconical stop surface, the stop surface being radially spaced from the inner surface of the outer ring or the outer surface of the inner ring, and engaging with the outer ring or the inner ring when one of the inner ring and the outer ring is radially or axially displaced relative to the other of the inner ring and the outer ring.

2. The hub bearing unit according to claim 1, wherein: The stop surface can contact an engagement surface on one of the inner ring and the outer ring, the engagement surface extending both axially and radially relative to the central axis.

3. The hub bearing unit according to claim 2, wherein: The engagement surface is provided by a portion of the outer surface of the inner ring or by a portion of the inner surface of the outer ring.

4. The hub bearing unit according to claim 2, wherein: The stop surface defines a first angle relative to the central axis, and the engagement surface defines a second angle relative to the central axis, the first angle having an angular value equal to the second angle.

5. The hub bearing unit according to claim 4, wherein: An annular control gap with a certain angle is defined between the stop surface and the engagement surface. The size of the displacement limiter and the angle values of the first angle and the second angle are selected so that the control gap has a predetermined radial length and a predetermined axial length, which are respectively used to limit the radial relative displacement between the inner ring and the outer ring to within the radial length of the control gap and to limit the axial relative displacement between the inner ring and the outer ring to within the axial length of the control gap.

6. The hub bearing unit according to claim 5, wherein: The radial length of the control gap is between 0.10 mm and 0.31 mm, and the axial length of the control gap is between 0.57 mm and 1.73 mm.

7. The hub bearing unit according to claim 5, wherein: The angle value of the first angle and the angle value of the second angle are between 10 degrees and 80 degrees.

8. The hub bearing unit according to claim 1, wherein: The displacement limiter is axially located between multiple rolling elements and the inner axial ends of the inner ring and the outer ring, so as to limit the relative displacement in the radial direction and the relative displacement in the axial direction between the inner axial end of the inner ring and the outer ring.

9. The hub bearing unit according to claim 1, characterized in that One of the following situations: The displacement limiter has a first radial end and a second radial end opposite to the first radial end, the first radial end being connected to or formed integrally with the inner ring, the second radial end being spaced radially inwardly from the inner circumferential surface of the outer ring so as to provide the stop surface; and The displacement limiter includes an annular body having a first radial end and a second radial end opposite to the first radial end, the first radial end being connected to or formed as one piece with the outer ring, and the second radial end being spaced apart from the outer circumferential surface of the inner ring on the radial outside, thereby providing the stop surface.

10. The hub bearing unit according to claim 1, wherein: The displacement limiter is connected to the inner ring or the outer ring in a removable manner.

11. The hub bearing unit according to claim 1, wherein: The displacement limiter comprises an annular body having oppositely disposed axial ends and a radial end providing the stop surface, the stop surface being continuous around the central axis or formed by a plurality of arcuate surface portions spaced circumferentially around the central axis.

12. The hub bearing unit according to claim 1, wherein: The inner ring includes an annular insert having an outer circumferential surface thereof providing a bearing inner ring raceway. The displacement limiter is provided on a portion of the outer surface of the insert and is spaced apart from the inner ring raceway in the axial direction.

13. The hub bearing unit according to claim 1, wherein: The inner ring raceway is a first inner ring raceway, and the inner ring further has a second inner ring raceway spaced apart from the first inner ring raceway in the axial direction; The outer ring raceway is a first outer ring raceway, and the outer ring further has a second outer ring raceway spaced apart from the first outer ring raceway in the axial direction; The plurality of rolling elements are a first plurality of rolling elements, and the hub bearing unit further comprises a second plurality of rolling elements capable of rolling on a second inner ring raceway and a second outer ring raceway.

14. The hub bearing unit according to claim 1, wherein: The inner ring is formed with a flange at an end portion outside the cabin thereof, and the flange can be connected to a wheel. The inner ring can rotate around a central axis, and the outer ring can be connected to a steering mechanism or a suspension.

15. A wheel hub bearing unit for rotatably connecting a wheel to a vehicle frame, the wheel hub bearing unit comprising: an inner ring connected to the wheel so as to be rotatable about the central axis, the inner ring having an inboard axial end, an outboard axial end, an outer circumferential surface, and at least one bearing inner ring raceway provided on the outer circumferential surface; an outer ring connected to the frame, disposed around the inner ring, having an inner axial end, an outer axial end, an inner circumferential surface, at least one bearing outer ring raceway disposed on the inner circumferential surface, and a frustoconical engagement surface portion recessed on the inner circumferential surface; a plurality of rolling elements, each of which is capable of rolling on the inner ring raceway and the outer ring raceway so as to rotatably connect the inner ring and the outer ring; as well as A displacement limiter extends radially from the outer circumferential surface of the inner ring and has a truncated conical protruding stop surface radially and axially spaced from the engaging surface portion of the outer ring, the displacement limiter being constructed so that the stop surface can contact the engaging surface when the inner ring is radially or axially displaced relative to the outer ring.

16. The hub bearing unit according to claim 15, wherein: The stop surface defines a first angle relative to the central axis, and the engagement surface defines a second angle relative to the central axis, the first angle having an angular value equal to the second angle.

17. The hub bearing unit according to claim 16, wherein: An annular control gap with a certain angle is defined between the stop surface and the engagement surface. The size of the displacement limiter and the angle values of the first angle and the second angle are selected so that the control gap has a predetermined radial length and a predetermined axial length, which are respectively used to limit the radial relative displacement between the inner ring and the outer ring within the radial length of the control gap and to limit the axial relative displacement between the inner ring and the outer ring within the axial length of the control gap.

18. The hub bearing unit according to claim 15, wherein: The displacement limiter is axially located between multiple rolling elements and the inner axial ends of each of the inner ring and the outer ring, so as to limit the radial and axial relative displacements between the inner axial ends of the inner ring and the outer ring.

19. The hub bearing unit according to claim 15, wherein: The displacement limiter includes an annular body having oppositely disposed axial ends and a radial end providing the stop surface, the stop surface being continuous around the central axis or formed by a plurality of arcuate surface portions spaced circumferentially around the central axis.

20. The hub bearing unit according to claim 15, wherein: The displacement limiter is removably coupled to the inner race.

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