Hub Bearing Unit with Combined Displacement Limiter and Seal

Abstract

A wheel hub bearing unit includes an inner ring having an axially inner end and an axially outer end and a bearing inner raceway on an outer surface. An outer ring arranged around the inner ring has an axially inner end and an axially outer end and a bearing outer raceway on an inner surface. One ring is connected to the wheel and can rotate about the axis, and the other ring is fixedly connected to the frame. An annular displacement limiter extends radially from one ring and has a circumferential stop surface radially spaced from the surface of the other ring. When one ring is radially displaced relative to the other ring, the stop surface engages with the ring surface. The seal includes an annular sealing member, which is connected to one ring and can be sealingly engaged with the limiter, or is mounted on the limiter and can be sealingly engaged with one ring or with a rigid sealing member connected to one ring.

Description

Technical Field

[0001] The present invention relates to bearings, and more particularly to wheel hub units. Background Art

[0002] Wheel hub units are known and are typically configured to rotatably couple a wheel to a vehicle frame. A vehicle hub unit comprises an inner ring, an outer ring, and rolling elements arranged between the inner and outer rings, wherein the wheel is mounted to one ring and the other ring is connected to the frame via an axle, suspension assembly, or steering mechanism. When a wheel experiences a side impact of sufficient magnitude, the relative displacement between the ring coupled to the wheel and the other ring may cause the rolling elements to impact the raceway with a force sufficient to indent the raceway surface. Such indentations, or "brinelling," may result in improper operation of the bearing and may lead to premature wear and failure of the bearing raceways. Summary of the Invention

[0003] In one aspect, the present invention is a wheel hub bearing unit for rotatably coupling a wheel to a vehicle frame. The wheel hub bearing unit includes an inner ring having an inboard axial end, an outboard axial end, a circumferential outer surface, and at least one inner bearing raceway disposed on the outer surface. An outer ring is disposed about the inner ring and has an axial inboard end, an axial outboard end, a circumferential inner surface, and at least one outer bearing raceway disposed on the inner surface of the outer ring. One of the inner ring and the outer ring is coupled to the wheel for rotation about a central axis, and the other of the inner ring and the outer ring is fixedly coupled to the frame. A plurality of rolling elements are rollable on the inner raceway and the outer raceway to rotatably couple the inner ring and the outer ring. Furthermore, a generally annular displacement limiter extends radially from the outer surface of the inner ring or the inner surface of the outer ring. The limiter has a circumferential stop surface radially spaced from the inner surface of the outer ring or the outer surface of the inner ring. The stop surface engages the outer ring or the inner ring when one of the inner and outer rings is radially displaced relative to the other. Furthermore, the seal includes an annular sealing member coupled to one of the inner and outer rings and sealingly engageable with the limiter, or mounted on the limiter and sealingly engageable with one of the inner and outer rings or with a rigid sealing member coupled to one of the inner and outer rings. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The foregoing summary of the invention and the detailed description of the preferred embodiments of the invention will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the invention, there are shown in the accompanying drawings presently preferred schematic embodiments. However, it should be understood that the invention is not limited to the precise arrangements and implementations shown. In the drawings:

[0005] Figure 1 is an axial cross-sectional view of a hub bearing unit according to the present invention, showing a combined displacement limiter and seal of a first configuration;

[0006] Figure 2 yes Figure 1 An enlarged view of the upper part;

[0007] Figure 3 yes Figure 1showing a first configuration of the combined displacement limiter and seal, wherein the limiter is spaced apart from the inner race;

[0008] Figure 4 yes Figure 3 Another view of a portion of the , showing the restraining member engaged with the inner race;

[0009] Figure 5 is a greatly enlarged cross-sectional view of a first configuration of a combined displacement limiter and seal shown separated from the remainder of the hub bearing unit;

[0010] Figure 6 is an axial cross-sectional view of a hub bearing unit according to the present invention, showing a second configuration of a combined displacement limiter and seal;

[0011] Figure 7 yes Figure 6 An enlarged view of the upper part;

[0012] Figure 8 yes Figure 6 an enlarged view of a portion of , showing a second configuration of the combined displacement limiter and seal, wherein the limiter is spaced apart from the outer race;

[0013] Figure 9 yes Figure 8 another view of a portion of the , showing the limiter engaged with the outer race; and

[0014] Figure 10 is a greatly enlarged cross-sectional view of a second construction of a combined displacement limiter and seal shown separated from the remainder of the hub bearing unit. DETAILED DESCRIPTION

[0015] Certain terms are used in the following description for convenience only and are not intended to be limiting. The words "inward," "inwardly," and "outwardly" refer to directions toward and away from, respectively, a designated centerline or geometric center of the described elements, as will be apparent from the context of the specification. Additionally, as used herein, the words "connected" and "coupled" are each intended to include a direct connection between two components without any intervening components, and an indirect connection between components with one or more intervening components. The terminology includes the words specifically mentioned above, their derivatives, and words of similar import.

[0016] Referring now in detail to the drawings, wherein like reference numerals are used to refer to like elements throughout, Figures 1 to 10The figure shows a hub bearing unit 10 for rotatably coupling a wheel 1 to a vehicle 2 preferably via a steering mechanism, a suspension ( / suspension) or a powertrain ( / powertrain) (e.g. Figure 1 ). The wheel hub bearing unit 10 mainly includes: an inner ring 12; an outer ring 14 arranged around the inner ring 12; at least one "row" or multiple "rows" of rolling elements 16 arranged between the inner ring 12 and the outer ring 14; an annular displacement limiter 18 for limiting the relative radial displacement between the rings 12 and 14; and a seal 20 connected to or engaged with the limiter 18. More specifically, the inner ring 12 is generally cylindrical and has an inboard axial end 12a, an axial outboard end 12b, a circumferential outer surface 13, and at least one bearing inner raceway 22 arranged on the outer surface 13, and preferably has a central hole 24, which is configured to receive the shaft 3 connected to the frame of the vehicle 2 or to the power system (not shown). The outer ring 14 is generally tubular and has an axially inner end 14 a , an axially outer end 14 b , a circumferential inner surface 15 and at least one bearing outer raceway 26 arranged on the ring inner surface 15 .

[0017] As discussed in further detail below, one of the inner ring 12 and the outer ring 14 is coupled to the wheel 1 so as to be movable about the central axis A. C 14 is fixedly or "non-rotatably" coupled to the frame 2. Furthermore, a plurality of rolling elements 16 can simultaneously roll on the inner raceway 22 and the outer raceway 26 to rotatably couple the inner race 12 and the outer race 14. Preferably, the rolling elements 16 are generally spherical balls, but alternatively, the rolling elements 16 can be cylindrical rollers, tapered rollers, needle rollers, or any other type of rolling element. Preferably, the inner race 12 and the outer race 14 are formed of a metallic material (such as high-carbon steel or medium-carbon steel), and the rolling elements 16 are formed of a metallic material (e.g., chrome steel) or a ceramic material (such as alumina).

[0018] Displacement limiter 18 is generally annular and formed from a substantially rigid material. Displacement limiter 18 is preferably formed from a metallic material such as mild steel, but may be formed from any suitable material (e.g., a rigid polymer or ceramic material). Limiter 18 extends radially from inner ring outer surface 13 or outer ring inner surface 15 and has a circumferential stop surface 19 radially spaced from outer ring inner surface 15 or inner ring outer surface 13. In other words, as limiter 18 extends radially outward from outer ring outer surface 13 of inner ring 12, stop surface 19 is radially spaced inward from inner surface 15 of outer ring 14 or from the circumferential inner surface of a component disposed within outer ring inner surface 15. Conversely, when limiter 18 extends radially inward from inner surface 15 of outer ring 14, stop surface 19 is spaced radially outward from outer surface 13 of inner ring 12, or from the circumferential outer surface of a component disposed on (inner) ring outer surface 13. In either case, when one of inner ring 12 and outer ring 14 is radially displaced relative to the other, stop surface 19 engages outer ring inner surface 15 or inner ring outer surface 13 (i.e., stop surface 19 engages outer ring inner surface 15 or inner ring outer surface 13 directly or through a connecting component) to “limit” the total potential relative radial displacement between rings 12, 14, thereby reducing or eliminating any potential impact damage to bearing raceways 22, 26.

[0019] More specifically, an annular control gap GC is defined between the stop surface 19 of the displacement limiter 18 and the outer ring inner surface 15, the inner ring outer surface 13, or another circumferential surface of an assembly arranged on either ring 12, 14, as the case may be. The size of the limiter 18 (i.e., the size in the radial direction) is designed so that the control gap GC has a predetermined radial length L R , to limit the relative radial displacement between the inner ring 12 and the outer ring 14 to the control gap radial length L R The control gap GC is dimensioned so that under normal vehicle operating ( / running) conditions, one of the rings 12 or 14 coupled to the wheel 1 can be moved about the central axis A. C Free spins.

[0020] However, when an impact event occurs (e.g., the wheel 1 hits a curb, a pothole, etc.), the resulting radial displacement of the wheel-coupled ring 12 or 14 relative to the other ring 14, 12 is prevented by the displacement limiter 18 from exceeding the radial length L of the control gap GC. RAs discussed above, excessive radial displacement of one ring 12 or 14 relative to the other ring 14, 12 may cause the rolling element 16 to impact the outer surface 22a, 26a of the raceway 22, 26 with a force sufficient to create an indentation in the surface 22a, 26a, such an indentation being referred to as "brinelling". Indentations typically result in excessive vibration or chattering of the rolling element 16 and accelerate wear of the raceway surfaces 22a, 26a, leading to galling and / or spalling or flaking off of the bearing material. Therefore, by limiting the relative radial displacement between the inner ring 12 and the outer ring 14, the displacement limiter 18 acts as an "anti-brinelling" device. Preferably, the radial length L of the control clearance GC is R has a value of about 0.3 mm or less (ie, not greater than about 0.3 mm), and may be in the range of between about 0.15 mm (or, even 0.04 mm) and about 0.30 mm. Such a value of the control gap radial length L R It has been determined that radial displacements of a magnitude that could cause brinelling impacts can be prevented while still allowing free relative rotation between the rings 12 , 14 during normal vehicle operating conditions.

[0021] Furthermore, displacement limiting members 18 are preferably positioned axially between the plurality of rolling elements 16 (preferably forming an inner row 17A of rolling elements 16, as described below) and the axially inner end portions 12a, 14a of each of the inner ring 12 and the outer ring 14. In this manner, limiting members 18 serve to more effectively limit relative radial displacement between the axially inner end portion 12a of the inner ring 12 and the axially inner end portion 14a of the outer ring 14, thereby better maintaining the surface integrity of the inner inner raceway 23A and the inner outer raceway 27A, respectively (as described below).

[0022] Furthermore, the seal 20 includes a generally annular sealing member 30 that is preferably formed of an elastomeric material (but may be formed of any other suitable material) and includes one or more sealing lips 36. An important aspect of the present invention is that the seal 20 is coupled or sealingly engaged with the displacement limiter 18. More specifically, as Figures 1 to 5 As depicted, in certain configurations, an annular sealing member 30 is mounted on the restraint 18 and, depending on the number and configuration of one or more sealing lips 36, may sealingly engage one of the inner and outer races 12, 14, or / and a rigid sealing member 32 coupled to one of the inner and outer races 12, 14. Figures 6 to 10In the other configuration shown, an annular sealing member 30 is preferably coupled to one of the inner race 12 and the outer race 14 by a rigid retainer 34 as described below and is sealingly engageable with the restraint 18 .

[0023] In either configuration, the seal 20 and the restraint 18 are preferably provided as a unitary assembly or a "cassette" type seal. That is, all of the seal assemblies (i.e., the combination of the rigid retainer 34, the sealing member 30, and the restraint 18, or the combination of the restraint 18, the sealing member 30, and the rigid sealing member 32) are each preferably provided as a unit that can be installed in the wheel hub unit 10 as a single device and, alternatively, can be removed from the wheel hub unit 10 as a single device. However, alternatively, any or all of the seal assemblies can be installed on or removed from the wheel hub unit 10 separately, and / or the restraint 18 can be integrally formed with one of the rims 12, 14 and the seal member 30 then attached to or mounted against the integral restraint 18. Having described the basic components above, these and other structural components of the hub bearing unit 10 are described in detail below.

[0024] Reference Figures 3 to 5 as well as Figures 8 to 10 The displacement limiter 18 preferably includes a generally annular body 40 having a radially inner end 41A, a radially outer end 41B, and opposing axial ends 40a, 40b with radial end surfaces 42A, 42B. The body 40 is preferably generally cylindrical, such that the two radial end surfaces 42A, 42B are substantially flat and parallel, but may be formed in any other suitable manner. For example, the body 40 may be tapered to have generally frustoconical end surfaces 42A, 42B (not shown). In addition, the annular body 40 has at least one circumferential surface 43 or 44 that provides the stop surface 19, and when the annular body 40 is formed separately from the two rings 12, 14, the annular body 40 has oppositely facing circumferential surfaces 44, 43, respectively.

[0025] More specifically, when the displacement limiter 18 is connected to the inner race 12, the radially inner end portion 41A is coupled to or integrally formed with the inner race 12, and the radially outer end portion 41B is radially spaced inward from the outer race inner surface 15. When the limiter body 40 is formed separately from the race 12, the limiter body 40 further includes a circumferential inner surface 43 that engages with the inner race 12, such as by an interference fit with the outer surface 13, by being disposed within an annular groove (not shown) extending inward from the outer surface 13, or by being threadedly engaged with the outer surface 13. Alternatively, when the limiter 18 is connected to the outer race 14, the body radially outer end portion 41B is coupled to or integrally formed with the outer race 14, and the radially inner end portion 41A is radially spaced outward from the inner race outer surface 13. Similar to the above, when the body 40 is formed separately from the ring 14, the body 40 also has a circumferential outer surface 44 that engages the outer ring 14 in any suitable manner, such as frictionally engaging the inner surface 15, being disposed in an annular groove (not shown) extending radially outward from the inner surface 15, threadedly engaging the inner surface 15, etc. Moreover, with any configuration, the annular body 40 can be removably coupled with either the inner ring 12 or the outer ring 14, or can be permanently or semi-permanently attached to either ring 12, 14, such as by welding, brazing, etc.

[0026] Now refer to Figures 1 to 5 When the annular sealing member 30 is arranged on the displacement limiting member 18, the limiting member 18 is preferably coupled to the outer ring 14, and the wheel 1 is coupled to the inner ring 12 so that the inner ring 12 can be moved around the center axis A. C Preferably, radially inner end 41A of restrictor body 40 has a counterbore section 45 adjacent stop surface 19 to provide clearance for sealing lip 36 as discussed below, and radially outer end 41B has an axial extension 46. Axial extension 46 provides a circumferential inner surface 46a and a circumferential outer surface 46b for supporting portions of annular seal member 30.

[0027] Furthermore, the seal member 30 is preferably bonded to at least the outwardly facing radial surface 42B of the restrictor annular body 40, and preferably also to the counterbore portion 45 and the axial extension 46. Preferably, the seal member 30 includes a generally axial primary sealing lip 37 and at least one radial sealing lip 38 that is sealingly engageable with the radial surface 33 of the rigid seal member 32. The radial sealing lip 38 extends generally radially inward from the restrictor counterbore portion 45 and is preferably sealingly engageable with the outer peripheral surface 35A of the rigid member 32, but alternatively may engage a portion of the outer surface 13 of the inner race 12.

[0028] Furthermore, the rigid seal member 32 is formed of a generally rigid material (such as steel, aluminum, rigid plastic, etc.), is preferably generally L-shaped including an axial portion 50 and a radial portion 52, and generally functions as a "flinger." More specifically, the rigid member axial portion 50 provides an outer circumferential seal engagement surface 35A and has an opposing circumferential inner surface 35B that frictionally engages the inner race outer surface 13 to couple the seal member 32 to the inner race 12. Furthermore, a portion of the outer circumferential surface 35A of the axial portion 50 provides a limiter contact surface 51 that can engage the limiter stop surface 19 (e.g., when the inner race 12 is displaced relative to the outer race 14) when the inner race 12 is displaced relative to the outer race 14. Figure 4 ). Moreover, the rigid member radial portion 50 provides the radial seal engagement surface 33 and serves to “fling” or direct fluid and solid material that contacts the surface 33 radially outward and generally away from the axial seal lip 37 during rotation of the inner ring 12.

[0029] While displacement limiter 18 is preferably mounted to stationary outer ring 14 when configured to serve as a carrier for seal member 30, alternatively, limiter 18 may be coupled to and extend outwardly from stationary inner ring 12, with rigid seal member 32 suitably mounted to rotatable outer ring 14 (configuration not shown). As another alternative, limiter 18 may be coupled to either rotatable inner ring 12 or rotatable outer ring 14, carrying rotatable seal member 30, wherein rotatable seal member 30 may sealingly engage stationary rigid member 32, which is correspondingly coupled to non-rotatable outer ring 14 or non-rotatable inner ring 12 (alternative not shown). As yet another alternative, seal 20 may be formed without a rigid seal member or retainer, with seal member 30 formed with only one or more radial sealing lips 38 that may sealingly engage inner ring outer surface 13, outer ring inner surface 15, or a circumferential surface of a member disposed on either ring 12 or 14 (alternative not shown). The present invention encompasses these and all other suitable alternative configurations as generally disclosed or suggested herein.

[0030] Now refer to Figures 6 to 10 When the annular sealing member 30 is sealingly engaged with the displacement limiter 18 and is therefore not supported thereby, the limiter 18 preferably acts as a retainer (as discussed below) and is coupled to the inner ring 12 to which the wheel 1 is mounted so that the ring 12 can be moved about the central axis A. C Preferably, the radially inner end 41A of the restrictor body 40 has an axial extension 47 that provides a sealingly engaging circumferential outer surface 47a, and the radially outer end 41B has a radially inward stepped portion 48 adjacent the stop surface 19. In this manner, the restrictor body 40 is partially disposed within the rigid retainer 34, while the stop surface 19 is positioned exterior to the retainer 34 to define a control gap GC with the inner surface 15 of the outer race 14. Furthermore, the radially inner end 41A of the restrictor body 40 preferably has a circumferential inner surface 43 that frictionally engages the outer surface 13 of the inner race 12 (preferably, the outer surface 13 of an insert 62, described below), to removably couple the restrictor 18 to the race 12.

[0031] Furthermore, when the sealing member 30 is not mounted on the displacement limiter 18, the seal 20 preferably also includes an annular rigid retainer 34, which is most preferably coupled to the outer ring 14 and is generally L-shaped. Specifically, the retainer 34 includes an outer axial portion 34a that frictionally engages the inner surface of the outer ring 14, and a radial portion 34b that extends inwardly from the axial portion 34b. The annular sealing member 30 is coupled to the rigid retainer 34, preferably being bonded to both the radial portion 34b and the axial portion 34a. The sealing member 30 preferably includes a primary axial sealing lip 37 that sealingly engages the inwardly facing radial surface 42A of the limiter 18; a radial sealing lip 38 that sealingly engages the circumferential outer surface 47a of the limiter's axial extension 47; and a dust lip 39.

[0032] In the above restrictor and seal configuration, the displacement restrictor 18 also functions as a retainer to direct fluids and solids away from the sealing member 30. That is, as the restrictor 18 rotates with the inner ring 12, centrifugal force causes fluids and solids on the radial surface 42A of the restrictor body 40 to be directed radially outwardly away from the axial sealing lip 36, thereby increasing the effectiveness of the seal 20. Furthermore, due to the limited space through the control gap GC, the displacement restrictor 18 provides a labyrinth seal ( / labyrinth seal) function to prevent or at least limit the flow of fluids or solids through the control gap GC and toward the axial sealing lip 36. Furthermore, as shown in FIG. Figure 9 As shown, the displacement limiter 18 can also serve as a mounting bracket or support for a sensor encoder 60, which can be connected to or mounted to the outward-facing radial surface 42B of the limiter body 40 to provide a target ( / object) for a sensor (not shown) connected to the outer ring 14.

[0033] While the displacement limiter 18 is preferably mounted to the rotating inner ring 12 when configured to function as a slinger, the limiter 18 may alternatively be coupled to an inward extension from the rotating outer ring, with the retainer and sealing member 30 suitably mounted to the stationary inner ring 12. As another alternative, the limiter 18 may be coupled to either the stationary inner ring 12 or the stationary outer ring 14 and sealingly engaged by a sealing member 30 coupled to the rotatable outer ring 14 or rotatable inner ring 12, respectively. The present invention encompasses these and all other suitable alternative configurations as generally disclosed or suggested herein.

[0034] Reference Figure 1 、 Figure 2 、 Figure 6 and Figure 7Wheel hub unit 10 is preferably a double-row bearing 11 including two sets of inner and outer raceways and two sets of rolling elements. Specifically, inner ring 12 has a first (inner) inner raceway 23A and a second (outer) inner raceway 23B axially spaced from first inner raceway 23A. Similarly, outer ring 14 has a first (inner) outer raceway 27A and a second (outer) outer raceway 27B axially spaced from first outer raceway 27A. Furthermore, a plurality of rolling elements 16 of a first or first row 17A are arranged between and rollable on first inner raceway 23A and first outer raceway 27A, and a plurality of rolling elements 16 of a second or second row 17B are arranged between and rollable on second inner raceway 23B and second outer raceway 27B. For the preferred double row bearing 11, as another option, the displacement limiter 18 may be arranged between the two rows 17A, 17B, or arranged outboard of the second or outboard row 17B of rolling elements 16. Although double row bearings are preferred, for some applications, as another option, the wheel hub unit 10 may be formed to include only a single row (not shown) of rolling elements 16.

[0035] Reference Figure 2 and Figure 7 Inner ring 12 preferably includes an annular insert 62 disposed within an annular groove 64 extending inwardly from ring outer surface 13 and retained by a flange or rolled end 64 formed on inner ring end 12a. Insert 62 has a circumferential outer surface 63 that provides a first (inner) inner raceway 23A and a portion 13a of ring outer surface 13. Seal stiffener 32 or limiter 18 is preferably disposed about outer surface portion 13a, thereby being mounted about insert 62. Alternatively, stiffener 32 or displacement limiter 18 may be integrally formed with insert 62, extending radially outwardly from insert outer surface 63 (structural details not shown). Furthermore, second (outer) inner raceway 23B is preferably formed directly on outer surface 13 of inner ring 12, and both first and second outer raceways 27A, 27B are formed directly on inner surface 15 of outer ring 14. However, as another option, either or both of the second inner raceway 23B or the outer raceways 27A, 27B may be provided by a suitable annular insert (not shown), or / and as another option, the first inner raceway 23A may be formed directly on the outer surface 13 of the inner ring 12 .

[0036] Now refer to Figure 1 and Figure 6In certain currently preferred configurations (as depicted), the inner ring 12 is a hub or "flange-coated inner ring" and includes a flange 64 formed on and extending radially outward from the inner ring outer end 12b. The flange 64 can preferably be connected to the wheel 1 by a plurality of bolts 65 to mount the wheel 1 to the wheel hub unit 10. As discussed above, in this configuration, the inner ring 12 can be rotated about the central axis A. C Rotation, and preferably, the central hole 24 receives the rotatable shaft 3 ( Figure 1 ) end. In addition, the outer ring 14 is preferably connected to the steering mechanism or suspension via a center flange ( / middle flange) 66 extending radially outward from the circumferential outer surface 68. However, as another option, the wheel hub unit 10 can be formed so that the outer ring 14 serves as a wheel hub and has a flange (not shown) formed on the outer end 14b of the ring 14 and extending radially outward from the outer end 14b of the ring 14. The flange can be connected to the wheel, and the outer ring 14 can be rotated around the center axis A C In this configuration, the inner race 12 is preferably mounted on a stub shaft (not shown) that is connected to the steering mechanism, suspension and / or powertrain.

[0037] Those skilled in the art will appreciate that changes may be made to the above-described embodiments without departing from the broad inventive concept of the present invention. Therefore, it should be understood that the present invention is not limited to the particular embodiments disclosed, but is intended to cover modifications within the spirit and scope of the present invention as generally defined in the appended claims.

Claims

1. A wheel hub bearing unit for rotatably coupling a wheel to a vehicle, the wheel hub bearing unit comprising: an inner ring having an axially inner end, an axially outer end, a circumferential outer surface, and a bearing inner raceway arranged on the outer surface; an outer ring arranged around the inner ring and having an axially inner end, an axially outer end, a circumferential inner surface, and a bearing outer raceway arranged on the inner surface, one of the inner ring and the outer ring being coupled to the wheel so as to be rotatable about a central axis, and the other of the inner ring and the outer ring being fixedly coupled to a frame; a plurality of rolling elements capable of rolling on the inner raceway and the outer raceway to rotatably couple the inner ring and the outer ring; a generally annular displacement limiter extending radially from the outer surface of the inner ring or from the inner surface of the outer ring, the limiter having a circumferential stop surface radially spaced from the inner surface of the outer ring or from the outer surface of the inner ring, the stop surface engaging the outer ring or the inner ring when one of the inner ring and the outer ring is radially displaced relative to the other of the inner ring and the outer ring; and A seal comprising an annular sealing member coupled to one of the inner and outer rings and capable of sealingly engaging with the restraint, or mounted on the restraint and capable of sealingly engaging with one of the inner and outer rings or with a rigid sealing member coupled to one of the inner and outer rings.

2. The hub bearing unit according to claim 1, characterized in that: An annular control gap is defined between the stop surface of the limiting member and the circumferential outer surface of the inner ring or the circumferential inner surface of the outer ring, and the size of the displacement limiting member is such that the control gap has a predetermined radial length to limit the relative radial displacement between the inner ring and the outer ring to the radial length of the control gap.

3. The hub bearing unit according to claim 2, characterized in that: The radial length of the control gap has a value of 0.3 mm or less.

4. The wheel hub bearing unit according to claim 1, characterized in that: The restricting member is axially positioned between the plurality of rolling elements and the axially inner end of each of the inner ring and the outer ring so as to restrict relative radial displacement between the axially inner end of the inner ring and the axially inner end of the outer ring.

5. The hub bearing unit according to claim 1, characterized in that: One of the following: The limiter includes a generally annular body having a radially inner end coupled to or integrally formed with the inner race and an opposite radially outer end spaced radially inwardly from the inner surface of the outer race and having a circumferential outer surface providing the stop surface; and The limiter includes a generally annular body having a radially outer end coupled to or integrally formed with the outer ring and an opposing radially inner end spaced radially outwardly from the outer surface of the inner ring and having a circumferential inner surface providing the stop surface.

6. The wheel hub bearing unit according to claim 1, characterized in that: The restraint includes a generally annular body that is removably coupled to the inner race or to the outer race.

7. The hub bearing unit according to claim 1, characterized in that: The sealing member is disposed on the restraint and has at least one sealing lip sealingly engageable with at least one of an outer surface of the inner race, an inner surface of the outer race, and a surface of the rigid sealing member.

8. The wheel hub bearing unit according to claim 7, characterized in that: The wheel is coupled to the inner ring so that the inner ring can rotate about the central axis, the limiter is coupled to the outer ring, the rigid sealing member is coupled to the inner ring, and the rigid sealing member has a radial surface for directing fluid and solid material radially outward and generally away from the at least one sealing lip during rotation of the inner ring.

9. The hub bearing unit according to claim 7, characterized in that: The sealing member includes: at least one radial sealing lip sealingly engageable with a circumferential surface of one of the inner ring, the outer ring and a portion of the rigid sealing member; and at least one axial sealing lip sealingly engageable with a radial surface of the rigid sealing member.

10. The hub bearing unit according to claim 1, characterized in that: The seal further comprises an annular rigid retainer coupled to the inner ring or to the outer ring, and the annular sealing member is coupled to the rigid retainer and has at least one sealing lip sealingly engageable with a radial surface of the restrictor.

11. The wheel hub bearing unit according to claim 10, characterized in that: The wheel is coupled to the inner ring such that the inner ring is rotatable about the central axis, the annular rigid retainer is coupled to the outer ring, and the restrictor is coupled to the inner ring such that during rotation of the inner ring, a radial surface of the restrictor directs fluid and solid material radially outward and generally away from the at least one sealing lip.

12. The wheel hub bearing unit according to claim 10, characterized in that: The sealing member includes at least one radial sealing lip sealingly engageable with a circumferential surface of one of the inner ring and the outer ring, and at least one axial sealing lip sealingly engageable with a radial surface of the restrictor.

13. The hub bearing unit according to claim 1, characterized in that: The sealing member is formed of an elastomeric material.

14. The hub bearing unit according to claim 1, characterized in that: The hub bearing unit further includes a sensor encoder coupled to the restriction member.

15. The wheel hub bearing unit according to claim 1, characterized in that: The inner raceway is a first inner raceway, and the inner ring further has a second inner raceway axially spaced apart from the first inner raceway; The outer raceway is a first outer raceway, and the outer ring further has a second outer raceway axially spaced apart from the first outer raceway; The plurality of rolling elements are a plurality of first rolling elements, and the hub bearing unit further includes a plurality of second rolling elements capable of rolling on the second inner raceway and the second outer raceway.

16. The hub bearing unit according to claim 1, characterized in that One of the following: The inner ring has a flange formed on an outer end portion thereof, the flange being connectable to a wheel, the inner ring being rotatable about a central axis, and the outer ring being connected to a steering mechanism or a suspension; and The outer ring has a flange formed on an outer side end thereof, the flange being connectable to a wheel, the outer ring being rotatable about a central axis, and the inner ring being connected to a steering mechanism or a suspension.

17. A wheel hub bearing unit for rotatably coupling a wheel to a vehicle, the wheel hub bearing unit comprising: an inner ring having an axially inner end, an axially outer end, a circumferential outer surface, and a bearing inner raceway arranged on the outer surface; an outer ring arranged around the inner ring and having an axially inner end, an axially outer end, a circumferential inner surface, and a bearing outer raceway arranged on the inner surface of the outer ring, one of the inner ring and the outer ring being coupled to the wheel so as to be rotatable about a central axis, and the other of the inner ring and the outer ring being fixedly coupled to a frame; a plurality of rolling elements capable of rolling on the inner raceway and the outer raceway to rotatably couple the inner ring and the outer ring; a generally annular displacement limiter extending radially from the outer surface of the inner ring or from the inner surface of the outer ring, the limiter having a circumferential stop surface radially spaced from the inner surface of the outer ring or from the outer surface of the inner ring, the stop surface engaging the outer ring or the inner ring when one of the inner ring and the outer ring is radially displaced relative to the other of the inner ring and the outer ring; and a seal including an annular sealing member coupled to one of the inner race and the outer race and sealingly engageable with the restrictor; The wheel is coupled to the inner ring so that the inner ring can rotate about the central axis; The restriction member includes a generally annular body having: a radially inner end coupled to or integrally formed with the inner race; a radially outer end opposite the inner race, spaced radially inwardly from the inner surface of the outer race and having a circumferential outer surface providing the stop surface; and a radial engagement surface extending between the radially inner end and the radially outer end. as well as The seal also includes an annular rigid retainer coupled to the outer race, and the annular sealing member coupled to the rigid retainer and having at least one axial sealing lip sealingly engageable with the engagement surface of the restrictor.

18. A wheel hub bearing unit for rotatably coupling a wheel to a vehicle, the wheel hub bearing unit comprising: an inner ring having an axially inner end, an axially outer end, a circumferential outer surface, and a bearing inner raceway arranged on the outer surface; an outer ring arranged around the inner ring and having an axially inner end, an axially outer end, a circumferential inner surface, and a bearing outer raceway arranged on the inner surface, one of the inner ring and the outer ring being coupled to the wheel so as to be rotatable about a central axis, and the other of the inner ring and the outer ring being fixedly coupled to a frame; a plurality of rolling elements capable of rolling on the inner raceway and the outer raceway to rotatably couple the inner ring and the outer ring; a generally annular displacement limiter extending radially from the outer surface of the inner ring or from the inner surface of the outer ring, the limiter having a circumferential stop surface radially spaced from the inner surface of the outer ring or from the outer surface of the inner ring, the stop surface engaging the outer ring or the inner ring when one of the inner ring and the outer ring is radially displaced relative to the other of the inner ring and the outer ring; and A seal includes an annular sealing member disposed on the restraint and sealingly engageable with at least two of the inner race, the outer race, and a rigid sealing member coupled to one of the inner race and the outer race.

19. The hub bearing unit according to claim 18, characterized in that: The wheel is coupled to the inner ring so that the inner ring can rotate about the central axis; The restriction member includes a generally annular body having: a radially outer end coupled to or integrally formed with the outer ring; and an opposite radially inner end spaced radially outwardly from the outer surface of the inner ring and having a circumferential inner surface providing the stop surface; as well as The seal includes a rigid sealing member having a radial engagement surface, and the sealing member includes at least one axial sealing lip sealingly engageable with the engagement surface of the rigid sealing member.

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