An improved bearing and brake member assembly for motor vehicles, provided with an intermediate connection element between the bearing and the brake member

Abstract: A disc or drum brake member is usually connected to the flange of the bearing of a motor vehicle wheel; possible manufacturing errors in the flange of the bearing, and/or the brake member cause, on tightening the wheel to the flange, deformations in the bearing tracks and the active surfaces of the brake member; to avoid this, an elastically-yielding connection element (1) is interposed, connected to the bearing (3) on one side and the brake member (4) on the other side, and constituted by a bell of sheet metal (10), dimensioned to present a high torsional rigidity associated with a limited axial rigidity to absorb and neutralise the tensions produced on tightening the screws (6) holding the wheel to the flange (7) of the bearing, even in the presence of manufacturing errors on the corresponding facing surfaces of the parts to be joined.

Description: The present invention concerns an improved bearing-and-brake-member assembly for a motor vehicle, provided with an intermediate connection element between the bearing and the brake member, and more particularly it concerns the mounting of a brake member such as a disc or drum on a rotating ring of a bearing of a driving wheel or a free wheel of a motor vehicle. It is known that disc or drum brake members for motor vehicles like that one shown in EP-A-0309174 are mounted directly on the rotating ring of the wheel bearing, which is provided with a radial flange to which the disc or drum is connected; in particular, the disc, preferably associated with a driving wheel, is mounted in contact with a flange of the inner ring of the bearing, and fixed to the wheel by means of bolts screwed to the flange, or nuts screwed to captive bolts fixed to the flange; similarly, the drum, usually associated with a free wheel, is connected to the flange of a rotating outer ring of the bearing, fixed to the wheel by bolts screwed to the flange, or nuts screwed to captive bolts fixed to the flange. Due to working tolerances in the manufacture of the wheel, the flange and the brake member, it is not possible to avoid irregularities in the flatness of the facing surfaces of the parts to be joined together. Such flatness errors give rise on tightening the bolts to deformations in the bearing tracks and the active surfaces of the brake members (on which the brake pads or shoes act) in the form of ovalization, undulations and the formation of lobes. These disadvantages give rise to vibrations, braking noise and irregular wear of the active surfaces of. the brake members, in addition reducing the resistance of the bearing to fatigue. A known solution to these disadvantages is to use components (wheels, braking members, bearing flanges) manufactured to high precision or, alternatively, to use a bearing having a flange of great thickness and rigidity so as to resist the deformations caused by tightening the wheel-fixing screws. However, these solutions are disadvantageous in terms of their effect on the cost and weight of the assembly. The aim of the present invention is to provide a bearing-and-brake-member assembly free from the disadvantages described above, and in which tightening the wheel-fixing nuts does not give rise to tensions and deformations in the rolling tracks of the bearings, and in which deformations of the active surfaces of the brake members, which are mounted with the wheel on the bearing itself, are minimised. Therefore, in accordance with the present invention, there is provided a bearing-and-brake-member in accordance with claim 1. This and other characteristics of the invention will become clearer from the following description of a preferred embodiment, given by way of non-limitative example, with reference to the accompanying drawings in which: Figure 1 shows an example of mounting the brake disc using an intermediate connection element, according to the invention; Figure 2 shows a different way of fixing the connection element of Figure 1 to the flange of the bearing and the brake disc; Figure 3 shows one kind of mounting of the connection element to the outer ring of the bearing; Figure 4 shows a different kind of mounting for the connection element of Figure 3; Figure 5 is a perspective view of the connection element used in Figures 3 and 4; Figure 6 shows a further embodiment of the connection element according to the invention, for a drum brake; and Figure 7 shows the mounting of Figure 1 seen on a different section plane, along a radial slot of the connection element. With reference to Figures 1 to 4 and 6 to 7, a connection element 1 is interposed between a ring 2 of a bearing 3 and a brake member 4 for the wheel of a motor vehicle (not illustrated), a rim 5 of which is fixed by bolts 6 to a flange 7 of the ring 2; the connection element 1 is constituted by a substantially annular plate 10 of pressed sheet metal; it is used, according to the invention, to absorb the stresses and possible deformations created on respective active surfaces 9 of the brake members 4 by the tightening of the screws 6, on mounting and tightening the wheel 5 on the flange 7 of the bearing, which deformations are caused, as is known, on tightening the wheel to the flange due to irregularities in the flatness of the facing surfaces of the wheel, the flange and the brake member. A first embodiment of the connection element 1, illustrated in Figures 1 and 2, consists in forming the sheet metal plate 10 into a shape, seen in diametral section, having two adjacent and opposite folds 11a and 11b forming an approximate Z-shape, possibly having slots 11c (Figure 7) which extend radially to ensure a high torsional rigidity and strength and, at the same time, a limited axial rigidity (in the sense that it is much lower than the torsional rigidity), to ensure the efficient elastic absorption of the axial deformations produced on tightening the bolts for attaching the wheel 5 to the flange 7. In particular, as shown in Figure 1, the plate 10 has a central hole 12 to allow the body 14 of the bearing 3 to pass through; the plate 10 is joined to a brake disc 15 by a fixing system constituted by a circle of cold-upset rivets 16 lying in a circle close to the edge of the plate 10. The plate 10 is also connected to the flange 7 by a series of captive bolts 17 inserted in corresponding holes disposed in an inner ring close to the edge of the central hole 12; these same bolts also serve to mount the wheel 5; in this case, the bolts 17 are held captive on the flange 7 after having mounted the plate 10 in place; after having assembled the assembly comprising the brake disc 15, the plate 10, and the bearing ring 2, the disc 15 is worked to make the two active surfaces 9 substantially coplanar and centred with respect to the axis of rotation A-A of the bearing. To facilitate the mounting and initial centering of the brake disc 15 on the connection element 1, the plate 10 (Figure 5) is provided with tabs 18 blanked and folded axially at approximately 90°, and for engaging with an internal cylindrical surface 19 (Figure 1) of the disc 15. Figure 2 shows a variation of the attachment of the plate 10 respectively to the brake disc 15 and the flange 7 of the bearing 3; the disc 15 is attached to the plate 10 by bolts 20, while the plate 10 is welded at its inner edge to a side 21 of the flange 7, using spot welding or a continuous weld bead 22 effected, for example, using a laser process. The embodiments shown in Figures 1 and 2 are typically used on driving wheels in which the ring 2 of the bearing 3 is the inner ring, which is connected to the spindle of a constant-velocity universal joint; the outer ring 24 of the bearing 3 is in turn attached by means of a second flange 25 to a support, not shown, of the vehicle suspension. Figures 3 and 4 show, according to the invention, an application of the connection element 1, adapted to join a brake member 4 to the bearing of a free wheel; in these applications, the element 1 has a slightly different shape from that shown in Figures 1 and 2; here, the element 1 is constituted by an annular, flat plate 10 integral with a central, axially extending cylindrical sleeve 26 which is formed together with the plate 10 in a pressing operation, known in the related art. The plate 10 is again connected to the brake disc 15 by bolts 27, but other attachment systems may be used which may be better suited to the particular conditions of use; the plate 10 is mounted on the body 28' of a ring 28 of the bearing 3 (Figure 3), spaced from the flange 7; the sleeve 26 is joined to the ring 28 by means of forced coupling or knurling and is then fixed axially by means of swaging or rolling its outer edge 29 into a circumferential groove 30 of the ring 28. In particular, to make the transmission of torque between the connection element 1 and the bearing 3 more secure, the sleeve 26 is joined for rotation with the ring 28 by a splined coupling 30a, represented in broken outline in Figure 3 and constituted by two meshing sets of axial teeth formed respectively inside the sleeve 26 and outside the ring 28. A different way of mounting the element 1 to the ring 28 is shown in Figure 4: the sleeve 26 is interference fitted on a seat 31 of the ring 28 and spot welded by laser to form weld spots 32 disposed circumferentially around the outer cylindrical surface of the sleeve itself. Figure 5 shows the connection element 1 according to the invention in the form used in Figures 3 and 4; in Figure 5 it can be seen that the tabs 18 of the plate 10 are disposed circumferentially, concentric with the central hole 12, in a position substantially between the hole 12 and the outer edge 33; the tabs 18 are angularly equally spaced, and are intercalated between the holes 34 used for the attachment of the plate 10 to the brake disc 15. Figure 6 shows an application of the connection element 1 with a drum brake; this use is typical of a non-driven wheel, usually the rear wheel of a motor vehicle, and shows the element 1 mounted on the outer ring 35 of the bearing 3, while the inner ring 36 is ordinarily mounted on the spindle of the hub, not shown. In this application, the connection element 1 has a plate 10 of pressed sheet metal shaped with a wide semicircular portion 37, and possibly having radial slots for improving the capacity for absorbing the deformations created in the flange 7 by tightening the bolts 17 of the rim of the wheel 5; on one side the portion 37 extends axially with a cylindrical part 39 embedded in the thickness of the drum 40; on the opposite side, the plate 10 is formed with a flat annular zone 41 which can be fixed to the flange 7 by rivets 42.

Claims: A bearing-and-brake-member assembly for a wheel of a motor vehicle, in which at least one ring (2; 28) of the said bearing (3) is provided with a radial flange (7) to receive a rim of the said wheel (5) and to connect the said brake member (4) to the said bearing, and including an intermediate connection element (1) between the bearing and the brake member, characterised in that the said connection element (1) includes an annular metal plate (10) fixed to the said bearing ring (2; 28) and supporting the said brake member (15; 40),. the said metal plate being dimensioned to present a high torsional rigidity together with a limited axial rigidity, for absorbing deformations created in the said flange (7) on tightening the said wheel (5). A bearing-and-brake-member assembly according to Claim 1, characterised in that the said annular plate (10) is formed from pressed sheet metal and has, in diametral section, two opposite folds (11a; 11b) giving it a substantially Z-shape in the radial direction, and which is provided with a series of radially extending slots disposed along the said double fold. A bearing-and-brake-member assembly according to Claim 1 or 2, characterised in that the said annular plate (10) is carried on a cylindrical central sleeve (26) formed together with the said plate and extending axially, and that the said plate (10) is provided with a plurality of axially projecting tabs (18) equally spaced in a circle, to cooperate with the brake member (4) to facilitate the centering of the said brake member (4) on the said connection element (1). A bearing-and-brake-member assembly according to any preceding claim, characterised in that the said connection element (1) is joined to the said flange (7) by captive screws (17) which are also used to fix the said wheel (5) to the said flange (7). A bearing-and-brake-member assembly according to any of Claims 1 to 3, characterised in that the said connection element (1) is fixed securely to the said flange (7) by means of rivets. A bearing-and-brake-member assembly according to Claims 1 to 3, characterised in that the said connection element (1) is joined to the said flange (7) by welding the said plate (10) to a bearing ring (2; 28). A bearing-and-brake-member assembly according to Claim 2, characterised in that the said double fold includes a fold (37) having a wide radius of curvature and in that one rim (39) of the said plate adjacent the said fold (37) extends axially and is fixed to a drum brake member (40). A bearing-and-brake-member assembly according to Claim 3, characterised in that the said connection element (1) is fixed to a ring (28) of the said bearing by swaging an edge (29) of the said sleeve (26) into a circular groove (30) of the said ring (28). A bearing-and-brake-member assembly according to Claim 8, characterised in that the said connection element (1) is joined to the said ring (28) by means of a channelled coupling (30a), suitable to transmit a couple between the said connection element (1) and the said ring (28). A bearing-and-brake-member assembly according to Claim 3, characterised in that the said connection element (1) is joined to a ring (28) of the said bearing by welding the said sleeve (26) to the said ring (28) at a position spaced from the said flange (7) . any preceding claim, in which the said attachment element (1) is joined to the said brake member and the said bearing (3) by an irreversible connection to form an assembly, characterised in that the said assembly is further worked to provide the said brake member (15) with finished active surfaces (9). A bearing-and-brake-member assembly according to Claim 1, including a connection element suitable to connect a brake member (4) to a bearing (3) of a motor vehicle wheel, characterised in that the said connection element is constituted by an annular plate (10) of pressed sheet metal to be connected to the said brake member (4), and provided with a plurality of axially projecting, equally circumferentially spaced tabs (18) acting to keep the said brake member (4) centered on the said connection element (1), and a cylindrical sleeve (26) formed together with the said plate (10) for mounting the said connection element (1) to the said bearing (3).

Inventors: BERTETTI PAOLO, MORERO LUCA, BERTETTI, PAOLO, MORERO, LUCA
Applicants: SKF IND SPA, SKF INDUSTRIE S.P.A.
Application year: 1997
Main classification: B60T1
IPC codes: F16D65, B60T1