Wheel hub bearing unit

Abstract

A unit (1) forming a wheel hub unit (10) in which an outer bearing ring (11), which is stationary in use, and a flange body (22), which is directly connected to a column (M) of a vehicle in use, are provided with corresponding locking surfaces (43, 46) for locking the outer ring (11) in an assembly seat (24) of the flange body (22).

Description

Technical Field

[0001] This invention relates to a wheel hub bearing unit. Background Technology

[0002] The simplest known wheel hub bearing unit includes:

[0003] - The outer bearing ring, which is stationary during use and connected to the vehicle's pillar;

[0004] - A pair of radial inner bearing rings, which are not stationary during use, and are mounted axially side-by-side on a flanged wheel hub, which can be connected to the vehicle's wheel during use; and

[0005] - Two rings of a rolling member, located between the outer ring and the pair of radially inner bearing rings, so that the flanged wheel hub is rotatably and operably connected to the pillar of the vehicle.

[0006] The aforementioned wheel hub bearing unit is a first-generation type, in which the outer bearing ring is connected to the column by inserting the outer ring itself into a cylindrical housing created in the column itself, and is axially locked in the cylindrical housing by cold deformation of one or two axially opposite ends of the adjacent column of the outer ring or by using additional mechanical locking elements such as Seeger rings (the mechanical locking elements must be connected to the inner ring and then inserted together with the inner ring into the cylindrical housing to lock them together).

[0007] Instead, known types of wheel hub bearing units, considered to have more complex constructions, include:

[0008] - The outer bearing ring, which is stationary in use and has an outer flange for connecting it to the column of the vehicle;

[0009] - A hub and bearing ring with a center flange, which is radially inward and not stationary during use; the hub with the center flange is capable of being connected to the vehicle's wheel during use, and the radially inward bearing ring is integrally mounted to the center hub; and

[0010] - Two rings of a rolling element, respectively located between an outer ring, a central hub (with raceways directly formed for the rolling element to which the associated rings are formed), and a bearing ring (with another raceway formed for the rolling element to which the associated rings are formed) on the radially inner side.

[0011] Instead, the wheel hub bearing units just described are third-generation types, if (or even) they offer undeniable technical advantages compared to the aforementioned wheel hub bearing units (i.e., first-generation wheel hub bearing units) (such as being preferred by OEMs in the so-called "original equipment sector," i.e., during the assembly of production vehicles), (but) they seem less flexible and cost-effective for use in the "aftermarket" (i.e., the so-called vehicle service market).

[0012] In reality, if in the "original equipment" sector, wheel hub bearing units must possess technical characteristics that take into account the entire service life of the vehicle in which they are installed, then in the so-called "aftermarket" sector, wheel hub bearing units must possess technical characteristics that only consider the remaining lifespan of the vehicle. Therefore, arbitrarily and simply replacing third-generation wheel hub bearing units with similar ones is inconvenient, not only for vehicle users who will have to bear costs exceeding what is strictly necessary, but also for spare parts manufacturers who will have to continue producing wheel hub bearing units for vehicles that may no longer be commercially available. Summary of the Invention

[0013] Therefore, the object of the present invention is to provide a wheel hub bearing unit that preferably allows for replacement while maintaining a third-generation wheel hub bearing unit, not only using a much more economical first-generation wheel hub bearing unit, but also having the possibility of using a small number of first-generation wheel hub bearing units for a larger number of applications, thus providing undeniable advantages for both vehicle users and spare parts manufacturers (whereby these spare parts manufacturers no longer need to use the complex and expensive assembly systems described above).

[0014] According to the present invention, a wheel hub bearing unit having the features described in the appended claims is provided. Attached Figure Description

[0015] The invention will now be described with reference to the accompanying drawings, which illustrate non-limiting examples of embodiments of the invention, in which:

[0016] - Figure 1 This is an axial cross-sectional view of the wheel hub bearing unit according to the present invention;

[0017] - Figure 2 It shows according to Figure 1 The cross-section and larger-scale details of the wheel hub bearing unit; and

[0018] - Figure 3 It shows according to Figure 1Another detail of the cross-section and larger proportion of the wheel hub bearing unit. Detailed Implementation

[0019] Reference Figure 1 1 represents the overall (wheel) hub bearing unit, which has a central rotation axis X and includes a first-generation type wheel hub bearing unit 10, further comprising:

[0020] - Outer bearing ring ( / bearing outer ring) 11, which is stationary in use and connected to the vehicle's pillar (shown in dashed line and indicated by M);

[0021] - A pair of radial inner bearing rings ( / bearing radial inner rings) 12, which are not stationary during use; and

[0022] - Two rings 13 of the rolling member ( / rolling element) 14, which are located between the outer ring 11 and the pair of inner rings 12, so as to rotatably and operatively connect the vehicle's wheels (shown in dashed lines and indicated by R) to the vehicle's pillar M.

[0023] Throughout this specification and the appended claims, terms and expressions indicating position and direction (such as “radial” and “axial”) should be understood as relative to the axis of rotation x. Instead, expressions such as “axially internal” or “axially external” should be understood as referring to the condition of the wheel hub bearing unit mounted on the vehicle.

[0024] For the purpose of properly connecting the bearing 10 to the column M and to the wheel R, the unit 1 further includes:

[0025] - A flanged wheel hub 20 having an outer cylindrical assembly surface 21 for the pair of radially inner bearing rings 12, and being directly connected to the vehicle wheel R in use; and

[0026] - A flanged body 22, which is directly connected to the post M during use and has an inner cylindrical assembly surface 23, which is the cylindrical assembly surface for the outer ring 11, and together with the outer cylindrical assembly surface 21 defines an assembly seat 24 for the bearing 10; and

[0027] - Axial reference element 25, i.e. shoulder, which defines the inner cylindrical assembly surface 23 in the axial direction.

[0028] The pair of radial inner bearing rings 12 are keyed to the outer cylindrical assembly surface 21 of the flanged wheel hub 20, which (the flanged wheel hub 20) is connected to the vehicle wheel R in a known manner during use, while the outer ring 11 is mounted axially adjacent to the shoulder 25 and in direct contact with the inner cylindrical assembly surface 23 of the flange body 22, which is thus connected to the vehicle column M in a known manner.

[0029] exist Figure 1 In the example of the embodiment shown, the outer ring 11 and a pair of inner rings 12 are made of bearing steel, which may also be tempered to be able to withstand mechanical stresses (typically Hertzian contact), while the flanged wheel hub 20 and flange body 22 are made of untempered steel because they do not need to withstand stresses typically in Hertzian contact and mainly serve to structurally support the bearing 10.

[0030] Therefore, one of the main advantages that can be achieved using the wheel hub bearing unit 1 according to the invention is that, taking into account the proven fact that in known types of wheel hub bearing units, the most critical component (i.e., the component that bears the greatest wear and the greatest static and dynamic stress) is always the Hertz component (i.e., the bearing), while the support component (i.e., the mechanical element for connecting the bearing to the wheel R and to the column M) bears only a small degree of stress, even when exposed to mechanical stresses generally associated with vehicle driving. Therefore, although the overall structural dimensions of the flanged wheel hub 20 and the overall structural dimensions of the flange body 22 can vary depending on the application of the wheel hub bearing unit 1 (i.e., according to the size of the vehicle), without these modifications that lead to high production costs, the structural dimensions of the mounting base 24 and the bearing 10 can remain unchanged, thereby allowing the use of the same first-generation type of wheel hub bearing 10 without considering the application of the wheel hub bearing unit 1.

[0031] As established above, it is generally the case that when designing the overall dimensions of a wheel hub bearing unit based on the entire theoretical lifespan of the vehicle in question, the Hertz component is configured to have substantially larger dimensions than the support component, in terms of the stress that the Hertz component and the support component must withstand during the bearing's working life or theoretically during the theoretical lifespan of the vehicle in question. Therefore, the wheel hub bearing unit 1 according to the invention offers optimal advantages, particularly in the "aftermarket" aspect (i.e., in the so-called vehicle service market), where only the theoretical remaining lifespan of the vehicle in question is considered, and the bearing 10 can have mechanical resistance (especially wear resistance) characteristics even worse than those of bearings used for the same application in the "original equipment" stage.

[0032] To further improve the flexibility and impact of the wheel hub bearing unit 1 according to the invention from a cost perspective, the unit 1 also includes a locking device 40 for axially locking the bearing 10 inside the assembly seat 24 in cooperation with the shoulder 25; in fact, once the bearing 10 is arranged inside the assembly seat 24 during the assembly of the unit 1, the bearing 10 is securely locked on one axial side (i.e., the side with the shoulder 25), while the bearing 10 must also be locked on the opposite axial side (i.e., the side inserted into the assembly seat 24) to prevent it from subsequently coming out, and this locking action must be performed, particularly without relying on the expensive locking elements described above. Therefore, the locking device 40 is common with the outer bearing ring 11 and the flange body 22 and includes the following combination:

[0033] - A formed protrusion 41, preferably but not necessarily arranged at an entrance on the inner cylindrical assembly surface 23 of the assembly base 24 on the opposite side of the shoulder 25; and

[0034] - A shaped connecting groove 42 is formed in the outer cylindrical surface 11a of the outer ring 11 and is designed to engage with the shaped protrusion 41 when the bearing 10 is located in the assembly seat 24 and adjacent to the shoulder 25.

[0035] In particular, in the example of the embodiment shown here, the formed protrusion 41 is arranged at the entrance of the assembly base 24 along the inner cylindrical assembly surface 23, but it can also be advantageously arranged at any axial point on the inner cylindrical assembly surface 23 depending on the necessary design conditions. In this case, the formed connecting groove 42 is not axially open toward the outside of the bearing 10 as described and preferably shown here, but will also be axially closed on both sides.

[0036] according to Figure 2 As shown in detail, the formed protrusion 41 includes: an axially inner conical surface 43 (i.e., arranged and axially oriented towards the inside of the assembly base 24), an axially outer conical surface 44 (i.e., oriented towards the outside of the assembly base 24), and a flat connecting surface 45 located between the two conical surfaces 43 and 44. Here and below, the “taper” of a cone or a truncated conical surface (i.e., the taper of a conical surface truncated between two planes parallel to each other and perpendicular to the axis of symmetry of the conical surface around which the generatrix rotates) must be understood as indicating the direction in which the generatrix converges toward the axis of rotation X, i.e., the direction in which the apex or apex of the conical surface (or the cone defined by the conical surface) is located (or more appropriately, the sense).

[0037] according to Figure 3 As shown in detail, the formed groove 42 includes: a conical engagement surface 46 axially oriented from the surface 11a toward the outer side of the mounting base 24; and a corresponding flat surface 47 extending axially along the outer ring 11 from the conical engagement surface 46 at a position axially lowered relative to the surface 11a.

[0038] The inner conical surface 43 and the conical engagement surface 46 of the formed protrusion 41 are inclined in the same orientation relative to the axis X, arranged adjacent to each other, and both define an angle β and a corresponding angle α on the axis X. The magnitudes of angles β and α fall within the range of not less than 15° and not greater than 45°. In particular, the magnitude of angle α is greater than the magnitude of angle β. In fact, angle α is formed on the outer ring 11 and is made of such a material (as described above, made of tempered bearing steel), and angle β is formed on the flange 22 and is made of such a material (as described above, made of untempered steel). Since the magnitude of angle α is greater than the magnitude of angle β, the following effect is achieved: the conical engagement surface 46 abuts against the axially inner conical surface 43 with a sharp cutting edge, so as to substantially cut into the axially inner conical surface 43, providing a high degree of resistance to displacement or a high degree of resistance to the loosening of the locking action provided by the locking device 40. Various experimental tests have shown that if the magnitudes of angles β and α are less than 15°, the locking (or essentially engaging) action of the locking device 40 will not work (or be ineffective); conversely, if the magnitudes of angles β and α are greater than 45°, the resistance to displacement will not increase further, making the use of such large angles meaningless.

[0039] For the purposes of facilitating the insertion of the bearing 10 into the assembly seat 24 and ensuring that the protrusion 41 is sufficiently robust and resistant (i.e., easily produced by machining), the latter (i.e., the protrusion 41) has a radial height h from the inner cylindrical assembly surface 23, h being not less than 0.02 mm and not more than 0.2 mm. For sizes smaller than 0.02 mm, producing such a machined protrusion 41 would be particularly difficult and would not even be efficient for its intended purpose, while for sizes larger than 0.2 mm, the height h would be excessive, with the risk that the protrusion 41 (emphasis on its being made of untempered material) might be drawn during the press-fitting of the bearing 10, whose outer ring is made of tempered material.

[0040] For the purposes of facilitating the insertion of the bearing 10 into the mounting base 24 and ensuring that the protrusion 41 is sufficiently robust and resistant, the flat surface 45 has an axial length l, which is not less than 0.5 mm and not more than 2.5 mm. In particular, an axial length l less than 0.5 mm would make the protrusion 41 insufficiently robust for applied loads that tend to displace the bearing 10 or for bearing the press fit of the bearing 10; while an axial length l greater than 2.5 mm would make the protrusion 41 too long, thereby weakening the interaction between the mounting base 24 and the bearing 10.

[0041] Although examples of embodiments have been shown in the foregoing detailed description, it must be remembered that the illustrated embodiments are merely illustrative and should not be construed as limiting the scope, applicability, or construction in any way. Rather, the accompanying drawings and the foregoing detailed description will provide convenient guidance to those skilled in the art for carrying out the invention, and it should be understood that various changes can be made to the described values ​​without departing from the scope of the invention as defined in the appended claims and their legal equivalents.

Claims

1. A unit (1) for forming a wheel hub bearing (10), comprising: - Outer ring (11), which is stationary when in use and is connected to the vehicle's pillar (M). - A pair of radial inner bearing rings (12), which are not stationary during use, and - Two rings (13) of the rolling member (14), which are located between the outer ring (11) and the pair of radial inner bearing rings (12), so that the wheel (R) of the vehicle is rotatably and operably connected to the column (M) of the vehicle. The unit (1) is characterized in that it further includes: - A flanged wheel hub (20) having an outer cylindrical assembly surface (21) for the pair of radial inner bearing rings (12) and being connected to the wheel (R) of the vehicle in use, and - A flange (22), which is directly connected to the pillar (M) of the vehicle during use, and having: an inner cylindrical assembly surface (23) for the outer ring (11), the inner cylindrical assembly surface (23) and the outer cylindrical assembly surface (21) together forming an assembly seat (24) for the bearing (10); and an axial reference element (25) that defines the inner cylindrical assembly surface (23) in the axial direction, and characterized in that it includes a combined locking device (40) for axially locking the bearing (10) within the assembly seat (24) in cooperation with the axial reference element (25). The locking device (40) comprises the following combination: - A shaped protrusion (41) arranged along the inner cylindrical assembly surface (23), and - A shaped connecting groove (42) is cut out from the outer cylindrical surface of the outer ring (11) which is designed to engage with the shaped protrusion (41). The following combinations: - The formed protrusion (41) includes an inner conical surface (43) oriented toward the inside of the assembly base (24), an outer conical surface (44) oriented toward the outside of the assembly base (24), and a flat connecting surface (45) located between the two conical surfaces (43, 44), and - The formed connecting groove (42) includes a conical engagement surface (46) oriented toward the outside of the assembly base (24). The inner conical surface (43) of the formed protrusion (41) is inclined at a first angle (β) relative to the central axis of rotation (X), and the conical engagement surface (46) is inclined at a second angle (α) relative to the central axis (X), the second angle (α) being greater than the first angle (β).

2. The unit (1) for forming the wheel hub bearing (10) according to claim 1, characterized in that, The formed protrusion (41) is arranged at the entrance of the assembly base on the opposite side of the axial reference element (25) along the inner cylindrical assembly surface (23).

3. The unit (1) for forming a wheel hub bearing (10) according to claim 1, characterized in that, The magnitudes of the first angle (β) and the second angle (α) fall within a range of not less than 15° and not greater than 45°.

4. The unit (1) for forming the wheel hub bearing (10) according to claim 3, characterized in that, The radial height (h) of the formed protrusion (41) from the inner cylindrical assembly surface (23) is not less than 0.02 mm and not greater than 0.2 mm.

5. The unit (1) for forming the wheel hub bearing (10) according to claim 4, characterized in that, The axial length of the flat connecting surface (45) of the formed protrusion (41) is not less than 0.5 mm and not more than 2.5 mm.

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