Hub bearing assembly for a motor vehicle wheel

Hub bearing assembly for a vehicle wheel, the assembly having an axial tubular appendage capable of being inserted into a central hole of a wheel of the vehicle, and wherein the tubular appendage has a radially outer surface of substantially cylindrical shape; a collar of cylindrical shape being mounted on the tubular appendage so as to cover a second centring section of the radially outer cylindrical surface, and having an insert of metallic material and an inner coating layer which at least partially covers the insert and is formed on the insert by galvanizing.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on and claims priority under 35 U.S.C. § 119 to Italian Application No. 102019000013587, filed Aug. 1, 2019, the entire contents of which are incorporated herein by reference.

DESCRIPTION

Field

The present disclosure relates to a hub bearing assembly for a vehicle wheel.

Background

Hub bearing units for a vehicle wheel may include a hub that forms a tubular appendage projecting from the axially outer side of the hub and having an outer cylindrical surface for centring the wheel. The hub also forms a radially extended flange through which axial holes are formed for fastening bolts by means of which the wheel and a brake disc are fastened to the hub.

BRIEF DESCRIPTION OF THE INVENTION

The object of the present invention is to protect such cylindrical surfaces (or centring surfaces) in a simple, economical and effective way, while avoiding the drawbacks discussed above. Another object is to provide protection that can be applied speedily.

These objects are achieved, by a hub bearing assembly in accordance with this disclosure. A variety of embodiments in accordance with this disclosure are defined in the dependent claims.

DETAILED DESCRIPTION

When two metal parts come into contact with one another, the presence of moisture and/or oxygen in the air commonly causes oxidation and corrosion phenomena, for example galvanic corrosion, that occur at the interface of the hub surface for centring the wheel, and, in such an eventuality, the metal parts in contact, namely the wheel, brake disc and bearing on the “outboard”, or axially outer, side, tend to adhere firmly and are at risk of damage when they are forcibly separated from one another during maintenance operations.

In order to prevent the aforementioned drawback, various solutions have been proposed, for example the application of antioxidant materials to an outer cylindrical surface of the aforementioned tubular appendages, these materials typically being varnishes and setting in air or by the action of ultraviolet light sources, but such application takes time and is therefore incompatible with production processes requiring high speeds, especially if the drying or setting of the varnish takes place in air, while costly investment is necessary if the setting is accelerated by ultraviolet light.

With reference toFIG. 1, the whole of a hub bearing assembly is indicated by1.

The assembly10is used for rotatably mounting a wheel (not shown) on to an upright (not shown) in the suspension of a vehicle, around a central axis of rotation x. Throughout the present description and the claims, terms and expressions indicating positions and directions, such as “radial” and “axial”, are to be understood as relating to the axis of rotation x of the hub bearing unit.

The hub bearing assembly10includes a flanged hub12that is rotatable around the axis x, and a flange13fixed to the flanged hub12and transverse to the axis x. Flanged hub12and flange13are two metal elements, typically made of steel, which are connected to the wheel: for this purpose, axial holes (not shown) are formed through the flange13for receiving fastening bolts (not shown) by means of which a wheel (not shown) is fastened to the flanged hub12.

The flanged hub12forms a tubular appendage17, also known by the English term “spigot”, that projects from the axially outer side of the hub beyond the flange13. The tubular appendage17has a radially outer surface18, of substantially cylindrical shape, and comprises a first centring section18dnear the flange13and a second centring section18b, which continues axially beyond the first centring section18dand has a diameter B smaller than a diameter A of the first centring section18d. The two sections18dand18bare capable of forming a surface for centring a wheel and a brake disc, respectively, and are connected to one another by a link19, while the section18dis axially delimited by an outer lateral edge20of the tubular appendage17, transverse to the axis x.

The tubular appendage17is intended to be fitted into a central hole of the wheel, in a known way. In the present example, the appendage17is formed so as to be fixed to the hub12as one piece. In other embodiments (not shown), the tubular appendage17is formed by a separate tubular element, which is coupled to the rest of the hub so as to be fixed to it or integral with it.

The hub bearing assembly10comprises a collar30of cylindrical shape, which is made of metallic material, is mounted on the tubular appendage17so as to cover the radially outer cylindrical surface18, particularly so as to cover only the second centring section18b, and comprises a tubular portion or tubular insert31coaxial with the axis x and a flanged portion32transverse to the axis x and fixed to the tubular portion31. As is also shown inFIG. 2, the tubular portion31has a radially inner cylindrical surface31apositioned in direct contact with the second centring section18b, and a radially outer cylindrical surface31bcoaxial with the radially inner cylindrical surface31aand defining with the radially inner cylindrical surface31aa radial thickness S of the tubular portion31. The flanged portion32has an axially inner annular surface32apositioned in direct contact with the outer lateral edge20of the tubular appendage17, transverse to the axis x.

The thickness S of the cylindrical portion31is less than half the difference between the diameter A of the first centring section18dand the diameter B of the second centring section18b, while an axial length L of the tubular portion31is less than a distance between the outer lateral edge20of the tubular appendage17and the link19. This design of the collar30has been devised to avoid any mounting interference with the brake disc (not shown); in fact, since the axial position of the collar30on the tubular appendage17is determined by the abutment of the flanged portion32behind the outer lateral edge20of the tubular appendage17, the provision of an axial length L smaller than the distance between the outer lateral edge20and the link19prevents the tubular portion31from overlapping and/or interfering with the link19or interfering with the mounting of the brake disc. Additionally, since the thickness S of the cylindrical portion31is less than half of the difference between the diameter A and the diameter B, the radially outer cylindrical surface31balways remains radially separate from the first centring section18d, thus always allowing not only the convenient mounting of the brake disc but also the convenient mounting and removal of the wheel.

Additionally, the axial length L of the tubular portion31is preferably between a minimum value of 4 mm, below which it would not be possible to mount the collar30securely on the second centring section18b, and a maximum value of 10 mm, above which it would not be possible to fit the collar30on to the second centring section18bwithout deforming the collar30, even though the flanged portion32has a radial dimension D of between 1 and 6 mm. If the radial dimension D of the flanged portion32were less than 1 mm, there would not be a sufficient surface area for any pushing implement to exert the pushing action on the collar30required to fit it on to the second centring section18b, while if the radial dimension D of the flanged portion32were greater than 6 mm, the flanged portion32would be too rigid compared with the tubular portion31, which would tend to become conical during mounting.

In order to avoid any oxidation and corrosion phenomena, for example galvanic corrosion, which might occur at the interface between the second centring section18band the collar30, the latter, which, it will be recalled, is made of metallic material, or at least the tubular portion31is made of metallic material, further comprises a layer of coating material40made by galvanizing the collar30, and positioned to cover the radially inner cylindrical surface31aof the tubular portion31so as to be interposed between the second centring section18band the collar30. In some embodiments a layer of coating material40made by galvanizing the collar30is a galvanized coating material.

Preferably but not necessarily, the tubular appendage17also has an annular groove60formed through the second centring section18bto facilitate the mounting of the collar30on the tubular appendage17by acting as a basin for collecting any chips or fragments of metallic material that might be separated from the collar30or from the tubular appendage17as a result of the friction between the collar30and the tubular appendage17during mounting.

In addition to the embodiments of the invention as described above, it is to be understood that numerous other variants exist. It is also to be understood that said embodiments are provided solely by way of example and do not limit the object of the invention or its applications or its possible configurations. 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 configurations, it is to be understood that numerous variations of the components described may be envisaged without thereby departing from the object of the invention as defined in the appended claims, interpreted literally and/or according to their legal equivalents.