Wheel hub bearing assembly for a motor vehicle wheel

Abstract

A wheel hub bearing assembly for a vehicle wheel, the wheel hub bearing assembly having an axial tubular attachment (17) that can be inserted into a center hole of a vehicle wheel, wherein the tubular attachment (17) has a radial outer surface (18) in a generally cylindrical shape, the wheel hub bearing assembly also having a cylindrical collar (30), the collar (30) being mounted on the tubular attachment (17) so as to cover a second centering portion (18b) of the cylindrical radial outer surface (18), and the collar (30) having an insert (31) made of a metal material and an inner coating (40), the inner coating (40) at least partially covering the insert (31) and being formed on the insert (31) by electroplating.

Description

Technical Field

[0001] The present invention relates to a wheel hub bearing assembly for a vehicle wheel. Background Art

[0002] A wheel hub bearing unit for a vehicle wheel is known, wherein the wheel hub forms a tubular appendage protruding from the axially outer side of the wheel hub and has an outer cylindrical surface for centering the wheel. The wheel hub also forms a flange extending in the radial direction, through which axial holes are formed for fastening bolts, by which the wheel and the brake disc are fastened to the wheel hub.

[0003] When two metal parts are in contact with each other, the presence of moisture and / or oxygen in the air generally causes oxidation and corrosion phenomena, such as galvanic corrosion, which occurs at the interface of the hub surface used to center the wheel, and in this possible situation, the metal parts that are in contact on the "outside" or axially external side (i.e., wheel, brake disc and bearing) tend to adhere strongly and there is a risk of damage when they are forced apart from each other during maintenance operations.

[0004] In order to prevent the above-mentioned disadvantages, various solutions have been proposed, such as applying antioxidant materials to the outer cylindrical surface of the above-mentioned tubular attachments, these materials are usually varnishes and are cured (setting) in the air or by the action of ultraviolet light sources, but this application takes time and is therefore incompatible with production processes that require high speeds, especially when the drying or curing of the varnish is carried out in the air, while if the curing is accelerated by ultraviolet rays, expensive investments are required. Summary of the invention

[0005] The object of the present invention is to protect the above-mentioned cylindrical surfaces (or centering surfaces) in a simple, economical and effective manner while avoiding the drawbacks discussed above. Another object is to provide a protection that can be applied quickly.

[0006] According to the invention, these objects are achieved by a wheel hub bearing assembly according to the independent claim. Preferred embodiments of the invention are defined in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The invention will now be described with reference to the accompanying drawings, which show non-limiting examples of embodiments of the invention, in which:

[0008] - Figure 1 is an axial cross-sectional view of a hub bearing assembly according to an embodiment of the present invention, with portions removed for clarity; and

[0009] - Figure 2 Belongs to Figure 1 A perspective view of the shaft collar of the assembly. DETAILED DESCRIPTION

[0010] Reference Figure 1 The wheel hub bearing assembly is generally indicated by reference numeral 10 .

[0011] The assembly 10 is used to rotatably mount a wheel (not shown) to an upright (not shown) in a suspension of a vehicle about a central axis of rotation X. Throughout the present specification and claims, terms and expressions indicating positions and orientations such as "radial" and "axial" are to be understood as relating to the axis of rotation X of the hub bearing unit.

[0012] The wheel hub bearing assembly 10 comprises a flanged hub 12 rotatable about an axis X and a flange 13 fixed to the flanged hub 12 and transverse to the axis X. The flanged hub 12 and the flange 13 are two metal elements connected to the wheel, typically made of steel. For this purpose, axial holes (not shown) are formed through the flange 13 to receive fastening bolts (not shown), by which the wheel (not shown) is fastened to the flanged hub 12.

[0013] The flanged hub 12 forms a tubular attachment (also called a "spigot") 17, which protrudes from the axially outer side of the hub beyond the flange 13. The tubular attachment 17 has a radially outer surface 18 of substantially cylindrical shape and comprises a first centering portion 18a close to the flange 13 and a second centering portion 18b which continues axially beyond the first centering portion 18a, the diameter B of the second centering portion 18b being smaller than the diameter A of the first centering portion 18a. The two portions 18a and 18b can respectively form a surface for centering the wheel and the brake disc and are connected to each other by a link 19, while the portion 18b is delimited axially by an outer lateral edge 20 of the tubular attachment 17 transverse to the axis X.

[0014] The tubular attachment 17 is intended to be fitted into the central hole of the wheel in a known manner. In the present example, the attachment 17 is formed so as to be fixed integrally to the wheel hub 12. In other embodiments (not shown), the tubular attachment 17 is formed by a separate tubular element that is coupled to the rest of the wheel hub and is thus fixed to the wheel hub or integral with the wheel hub.

[0015] The hub bearing assembly 10 comprises a collar 30 of cylindrical shape, made of a metal material and mounted on the tubular attachment 17 so as to cover the radially outer cylindrical surface 18, in particular only the second centering portion 18b, and the collar 30 comprises a tubular portion or tubular insert 31 coaxial with the axis X and a flange portion 32 transverse to the axis X and fixed to the tubular portion 31. In addition, as shown in Figure 2 As shown, the tubular portion 31 has a radially inner cylindrical surface 31a and a radially outer cylindrical surface 31b, the radially inner cylindrical surface 31a is positioned in direct contact with the second centering portion 18b, and the radially outer cylindrical surface 31b is coaxial with the radially inner cylindrical surface 31a and defines with the radially inner cylindrical surface 31a a radial thickness S of the tubular portion 31. The flange portion 32 has an axially inner annular surface 32a, which is positioned in direct contact with the outer lateral edge 20 of the tubular attachment 17 transverse to the axis X.

[0016] The thickness S of the cylindrical portion 31 is less than half the difference between the diameter A of the first centering portion 18a and the diameter B of the second centering portion 18b, while the axial length L of the tubular portion 31 is less than the distance between the outer lateral edge 20 of the tubular attachment 17 and the connecting portion 19. This design of the collar 30 has been designed to avoid any installation interference with a brake disc (not shown); in fact, since the axial position of the collar 30 on the tubular attachment 17 is determined by the flange portion 32 abutting behind the outer lateral edge 20 of the tubular attachment 17, the provision of an axial length L less than the distance between the outer lateral edge 20 and the connecting portion 19 prevents the tubular portion 31 from overlapping with the connecting portion 19 and / or interfering with or hindering the installation of the brake disc. In addition, since the thickness S of the cylindrical portion 31 is less than half the difference between the diameter A and the diameter B, the radially outer cylindrical surface 31b always remains radially separated from the first centering portion 18a, which always allows not only convenient installation of the brake disc, but also convenient installation and removal of the wheel.

[0017] In addition, the axial length L of the tubular portion 31 is preferably between a minimum of 4 mm and a maximum of 10 mm, below which the collar 30 cannot be securely mounted on the second centering portion 18 b, and above which the collar 30 cannot be assembled to the second centering portion 18 b without deforming the collar 30, even if the flange portion 32 has a radial dimension D between 1 mm and 6 mm. If the radial dimension D of the flange portion 32 is less than 1 mm, there will not be enough surface area for any pushing tool to exert a pushing action on the collar 30, which is required to fit the collar 30 to the second centering portion 18 b, and if the radial dimension D of the flange portion 32 is greater than 6 mm, the flange portion 32 will be too rigid compared to the tubular portion 31, which will tend to become tapered during installation.

[0018] In order to avoid any oxidation and corrosion phenomena, such as galvanic corrosion, that may occur at the interface between the second centering portion 18 b and the collar 30, it will be reiterated that the collar 30 is made of a metal material, or at least the tubular portion 31 is made of a metal material, and the collar 30 also includes a coating material layer 40, which is formed by galvanizing the collar 30 and is positioned to cover the radially inner cylindrical surface 31 a of the tubular portion 31 to be interposed between the second centering portion 18 b and the collar 30.

[0019] Preferably, but not necessarily, the tubular attachment 17 also has an annular groove 60 formed through the second centering portion 18b to facilitate installation of the collar 30 on the tubular attachment 17 by acting as a recessed portion ( / recessed portion / basin) to collect any debris or fragments of metallic material that may separate from the collar 30 or from the tubular attachment 17, thereby generating friction between the collar 30 and the tubular attachment 17 during installation.

[0020] In addition to the embodiments of the present invention as described above, it should be understood that there are many other variations. It should also be understood that the embodiments are provided only as examples and do not limit the purpose of the present invention or its application or its possible configuration. On the contrary, although the description given above enables those skilled in the art to implement the present invention according to at least one example of its configuration, it should be understood that it is possible to envision the various variations of the described components without therefore departing from the purpose ( / scope) of the present invention, which is limited by the appended claims, literally and / or interpreted according to its legal equivalents.

Claims

1. A wheel hub bearing assembly for a vehicle wheel, the wheel hub bearing assembly comprising an axial tubular attachment (17) insertable into a central hole of a wheel of the vehicle, wherein: The tubular attachment (17) has a radial outer surface (18) in a generally cylindrical shape. The wheel hub bearing assembly is characterized in that the wheel hub bearing assembly further comprises a cylindrical shaft ring (30), the shaft ring (30) being mounted on the tubular attachment (17) so as to cover a second centering portion (18b) of the cylindrical radial outer surface (18), and the shaft ring (30) comprises an insert (31) made of a metal material and an inner coating (40), the inner coating (40) at least partially covering the insert (31) and being formed on the insert by electroplating. On the insert (31), a radial outer surface (18) in a substantially cylindrical shape includes a first centering portion (18a) axially aligned with the second centering portion (18b), and the diameter (A) of the first centering portion (18a) is greater than the diameter (B) of the second centering portion (18b); the insert (31) defines a cylindrical portion of the collar (30) and has a radial thickness (S), and the radial thickness (S) is less than half of the difference between the diameter (A) of the first centering portion (18a) and the diameter (B) of the second centering portion (18b).

2. The wheel hub bearing assembly according to claim 1, characterized in that: The collar (30) comprises a flange portion (32) fixed to an insert (31) made of a metallic material, the insert (31) having an axial length (L) of a smaller dimension than the axial dimension of the second centering portion (18b).

3. The wheel hub bearing assembly according to claim 2, characterized in that: The axial length (L) of the insert (31) is between a minimum of 4 mm and a maximum of 10 mm.

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