Patent ID: 12196265

For greater clarity, identical or similar elements are identified by identical reference signs in all of the figures.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG.1shows a rotating assembly for guiding a motor vehicle drive wheel10, comprising a fixed outer subassembly12, intended to be secured to a suspension member of a motor vehicle (not shown) and defining an axis of rotation100, an inner rotating subassembly14, capable of rotating about the axis of rotation100inside the fixed outer subassembly12, and guide balls16,18between the rotating subassembly14and the fixed subassembly12.

The fixed outer subassembly12here is constituted by a one-piece solid metal outer race20on which a first outer raceway22and a second outer raceway24, coaxial, are formed that define the axis of rotation100. The outer race further comprises at least one attachment clamp26extending radially outward, in which bores (not shown in this figure) are formed for attaching the attachment clamp26to a suspension member, via attachment elements (not shown).

The inner rotating subassembly14comprises a wheel hub30, a transmission bowl32, an optional first inner bearing race34, and a second inner bearing race36.

The wheel hub30is a solid one-piece metal part, which comprises a flange38for attaching a drive wheel rim40and a brake disc41. The flange38has a face42bearing the brake disc41, and is provided with attachment bores43, allowing the insertion of attachment elements143of the rim40and of the brake disc41.

The wheel hub30also has a centering skirt44that projects axially with respect to the planar bearing face42, in a direction200of disassembly of the wheel rim40and of the brake disc41, and has a centering bearing45, preferably stepped, facing radially outward, comprising a first cylindrical portion for centering the wheel rim40and a second cylindrical portion, of equal or greater diameter, for centering the brake disc41during assembly. The centering bearing45is not necessarily intended to remain in contact with the rim40and the brake disc41after assembly.

The transmission bowl32is a solid one-piece metal part, which has a protruding end portion46and a flared middle portion48delimiting a cavity50of constant velocity joint. The protruding portion46of the transmission bowl32is preferably splined and mounted free, fitted or shrunk in a splined tubular cavity47of the wheel hub30, forming a splined contact interface. Furthermore,FIG.1shows means for attaching the transmission bowl32and the wheel hub30, which for example implement a nut188screwed to a threaded end190of the protruding portion46, and bearing against a shoulder84of the wheel hub30.

The first inner bearing race34is shrink-fitted on a cylindrical shrink-fit bearing52of the wheel hub30, bearing axially against an annular shoulder54formed on the wheel hub30. A first inner raceway56is formed on the first inner bearing race34facing the first outer raceway22.

The second inner bearing race36is also shrunk on the cylindrical shrink-fit bearing52of the wheel hub30, with a transverse end face57bearing axially against a transverse face59of the first inner bearing race34. The second inner bearing race36has an annular abutment face58, here frustoconical but which may be flat, axially facing away from the first inner raceway56, and axially protruding relative to the wheel hub30, so as to bear against an annular bearing face60formed on the transmission bowl32. A second inner raceway62is formed on the second inner bearing race36opposite the second outer raceway24. The balls16,18form, on the one hand, a first row of balls16that roll on the first outer raceway22and the first inner raceway56and, on the other hand, a second row of balls18that roll on the second outer raceway24and the second inner raceway62.

For the rest of the description, we will focus on certain remarkable dimensional characteristics of the assembly, which require some preliminary definitions. Thus, we note:PP1, the pitch plane where the pitch circle is located constituting the trajectory of the centers of the balls16of the first row of balls with nominal dimensions;PP2, the pitch plane where the pitch circle is located constituting the trajectory of the centers of the balls18of the second row of balls with nominal dimensions;DP1, the diameter of the pitch circle of the first row of balls16;DP2, the diameter of the pitch circle of the second row of balls18;CP1, a pitch cylinder centered on the axis of rotation100and having as its base the pitch circle of the first row of balls16;DC1, the diameter of the balls16of the first row of balls;DC2, the diameter of the balls18of the second row of balls;DI1, a raceway bottom diameter of the first inner raceway56, defined as the smallest diameter of the raceway56;DI2, a raceway bottom diameter of the second inner raceway62, defined as the smallest diameter of the raceway62;DE1, a raceway bottom diameter of the first outer raceway22, defined as the largest diameter of the outer raceway22;PB, a plane perpendicular to the axis of rotation100and tangent to the axial end face57of the second inner bearing race36;D, the distance between the plane PB and the first pitch plane PP1.

The first pitch plane PP1is located at a non-zero distance L from the second pitch plane PP2. Remarkably, the raceway bottom diameter DI2of the second inner raceway62is larger than the raceway bottom diameter DI1of the first inner raceway56, and preferably larger than the raceway bottom diameter DE1of the first outer raceway22. The second inner bearing race36therefore has a shape that flares out in the direction opposite the direction of disassembly, from the axial end face57, which makes it possible to accommodate part of the transmission bowl32inside the second inner bearing race36. The second inner bearing race36is housed in a cramped volume of generally frustoconical contour, between the outer bearing race20and the transmission bowl32. To give the second inner bearing race36a high stiffness, provision is made for the outer diameter of the inner bearing race36, measured radially with respect to the axis of rotation100, to increase rapidly as one moves away from the axial end face57.

This increase in diameter can be characterized by observing the outer diameter ϕ of the second inner bearing race36in a section plane PC perpendicular to the axis of rotation100and located between the first pitch plane PP1and the second pitch plane PP2, at a measurement distance DM from the first pitch plane PP1such that

DM=1.25⨯DC⁢12

Characteristically, the outer diameter ϕ is greater than a threshold value VS, which is equal to the greater of two values corresponding respectively to 110% of the raceway bottom diameter DI1of the first inner raceway56and to the sum of the raceway bottom diameter DI1of the first inner raceway56and of the radius of the balls16of the first row of balls:

{ϕ>VSVS=sup⁡(1.1⨯DI⁢1;DI⁢1+DC⁢12)

The plane PB, in which the contact interface between the axial end face57and the annular bearing face59is located, is preferably located between the first pitch plane PP1and the second pitch plane PP2, at a distance D from the first pitch plane PP1preferably less than half the diameter DC1of the balls16of the first row of balls. This positioning contributes to great axial compactness and excellent rigidity of the assembly10.

The balls16of the first row of balls are guided in the volume between the first inner raceway and the first outer raceway by a first one-piece bearing cage70, illustrated in detail inFIG.2, comprising a ring72defining a reference axis300of the first cage70and retaining claws74distributed around the periphery of the ring72to delimit cells76for housing the balls16of the first row of balls. The reference axis300of the first bearing cage70is intended to coincide with the axis of rotation100when the rotating assembly10is in a reference position.

The rapid increase in the outer diameter of the second inner bearing race36in the immediate vicinity of the first inner raceway56results in a reduced volume to position the first bearing cage70. In order to maximize the volume available for the second inner bearing race36in the space located between the first pitch plane PP1and the second pitch plane PP2, provision is advantageously made for the ring72of the first bearing cage to be positioned on a side of the first pitch plane PP1opposite the second pitch plane PP2. The retaining claws74extend from the ring toward the second pitch plane PP2crossing the first pitch plane PP1. The first cage therefore has no ring located between the first pitch plane PP1and the second pitch plane PP2, so that the retaining claws74have a free distal end78. The cells76are each delimited by two adjacent retaining claws74among the retaining claws of the first bearing cage70and by a portion of the ring72connecting the two adjacent retaining claws74.

For each of the cells76, the two adjacent retaining claws74each comprise a concave retaining guide facet80facing the ball16housed in the cell76, and the ring portion721connecting the two adjacent retaining claws74comprises an end guide facet82facing the ball16housed in the cell. The end guide facet82is located at least partially radially on the outside of a first pitch cylinder CP1whose base is the pitch circle of the first row of balls16and centered on the axis of rotation100. The retaining guide facets80are located at least partially inside the first pitch cylinder CP1and at least partially between the first pitch plane PP1and the second pitch plane PP2.

In this embodiment, the first bearing cage70further comprises additional claws84distributed around the periphery of the ring72, each of the additional claws84being associated with one of the retaining claws74and having a free distal end86located radially outside and facing the associated retaining claw74. For each of the cells, the two additional claws84associated with the two adjacent retaining claws74each comprise an additional concave guide facet88facing the ball16housed in the cell76, the additional guide facets88being located at least partially outside the first pitch cylinder CP1and at least partially between the first pitch plane PP1and the second pitch plane PP2. An enveloping cage70is thus produced, in the sense that the balls16cannot be inserted into the cells and can only be extracted therefrom by elastically deforming the retaining claws74or the additional claws84, or the retaining claws74and the additional claws84simultaneously. Thus, there is no risk of losing a ball during assembly.

The ring72of the first bearing cage70comprises a planar annular stacking face722axially facing away from the retaining claws74, and a centering bearing724having a symmetry of revolution about an axis of symmetry300of the first bearing cage70. The free ends86of the additional claws84face axially away from the planar annular stacking face722, superimposed with the planar annular stacking face722seen in orthogonal projection in a stacking plane containing the planar stacking face722. The retaining claws74in turn comprise centering facets742, facing radially away from the centering bearing724, so that, seen in orthogonal projection in the stacking plane, the centering facets742face the centering bearing724. Thus, when two bearing cages identical to the first one-piece bearing cage70are stacked on top of each other before they are mounted in the rotating assembly10, as illustrated inFIGS.3and6, the free ends86of the additional claws84of a bearing cage70bear against the annular stacking face722of the adjacent bearing cage70, while the centering facets742come opposite the centering bearing724, which ensures controlled relative positioning of the two bearing cages70and prevents them from becoming inextricably entangled.

The balls18of the second row of balls are guided in the volume between the second inner raceway62and the second outer raceway24by a second one-piece bearing cage90, comprising a ring92defining a reference axis of the second cage and retaining claws94distributed around the periphery of the ring92to delimit cells for housing the balls18of the second row of balls.

In order to maximize the volume available for the second inner bearing race36and the outer bearing race20in the space located between the first pitch plane PP1and the second pitch plane PP2, the ring92is preferably positioned on a side of the second pitch plane PP2opposite the first pitch plane PP1. The retaining claws94protrude from the ring toward the first pitch plane PP1while crossing the second pitch plane PP2. The retaining claws94have a free distal end98, cells each being delimited by two adjacent retaining claws94among the retaining claws of the second bearing cage90and by a portion of the ring92connecting the two adjacent retaining claws94. The second bearing cage90moreover has essentially the same configuration as the first bearing cage70, naturally with dimensions adapted to the diameter of the balls18and to the pitch diameter of the second row of balls18.

The outer raceways22,24formed on the outer bearing race20are enveloping in the axial direction, in the sense that they each have a raceway bottom64,66, located in an intermediate position between the axial ends of the corresponding raceway22,24.

In this embodiment, the balls forming the first row of balls16have a diameter DC1that is preferably less than or equal to the diameter DC2of the balls forming the second row of balls18. Choosing a relatively small diameter for the first row of balls16makes it possible to retain a sufficient axial thickness of the second inner bearing race36in the shrink-fit region on the wheel hub30, close to the first row of balls16, and to bring together the pitch planes PP1and PP2. The choice of a larger diameter for the second row of balls18makes it possible to ensure good load resistance, while maintaining a relatively small distance between the two pitch planes PP1and PP2.

The embodiment ofFIG.4differs from that ofFIG.1in that the first inner raceway56is formed directly on the wheel hub30, which thus constitutes the first inner bearing race34and has a shrink-fit bearing52and a shoulder159. The second inner bearing race36is thus shrink-fitted on the shrink-fit bearing52and axially bears against the shoulder159of the wheel hub30, and against the annular bearing face60of the transmission bowl32.

FIGS.5to6show a variant of the first bearing cage70, intended to equip the rotating assembly for guiding a drive wheel of a motor vehicle10ofFIG.1, or ofFIG.4. The first bearing cage70ofFIGS.5and6differs from the preceding ones in particular by the positioning of the first stacking face722, which is set back with respect to an axial end of the ring72of the bearing cage70, and by positioning and centering facets742, which are formed on the additional claws84.FIG.6in particular shows the cooperation between the centering facets742and the centering bearing724, and between the free ends86of the additional claws84and the annular stacking face722to allow stacking of the first bearing cages70on top of each other on an assembly line of the rotating assembly10.

FIGS.7to8show another variant of the first bearing cage70, intended to equip the rotating assembly for guiding a drive wheel of a motor vehicle10ofFIG.1, or ofFIG.4. The first bearing cage70ofFIGS.7and8differs from the previous ones in that it comprises only one set of solid retaining claws74, and no additional claws. The retaining claws74have retaining guide facets80that are intended to be located at least partially inside the first pitch cylinder CP1and at least partially between the first pitch plane PP1and the second pitch plane PP2, and additional guide facets88intended to be located at least partially outside the first pitch cylinder CP1and at least partially between the first pitch plane PP1and the second pitch plane PP2. An enveloping cage70is thus produced, in the sense that the balls16cannot be inserted into the cells and can only be extracted therefrom by elastically deforming the retaining claws74. In the embodiments ofFIGS.5to8, the balls16are mounted in the first bearing cage70by a movement having either a zero radial component or a radial component oriented toward the reference axis300.

FIGS.9to10show another variant of the first bearing cage70, intended to equip the rotating assembly for guiding a drive wheel of a motor vehicle10ofFIG.1, or ofFIG.4. The first bearing cage70ofFIGS.9and10differs from the previous ones in that it comprises only one set of hook-shaped retaining claws74, and no additional claws. The retaining claws74have retaining guide facets80that are intended to be located at least partially inside the first pitch cylinder CP1and at least partially between the first pitch plane PP1and the second pitch plane PP2, and additional guide facets88intended to be located at least partially outside the first pitch cylinder CP1and at least partially between the first pitch plane PP1and the second pitch plane PP2. An enveloping cage70is thus produced, in the sense that the balls16cannot be inserted into the cells and can only be extracted therefrom by elastically deforming the retaining claws74. This embodiment of the first bearing cage70differs from the previous ones also in that the balls16are mounted in the bearing cage70by a movement having a radial component going from the inside toward the outside of the bearing cage70.

In all embodiments, the second bearing cages90may be similar to the first bearing cages70.

Alternatively, the balls16,18of the two rows of balls may have the same diameter.

As a variant, it is possible to provide a fixed subassembly in several parts, with a clamp26in one or more parts forming the attachment clamp to a suspension element of the vehicle, and two coaxial outer bearing races shrunk in this clamp.

It is emphasized that all the features, as they will come to light for a person skilled in the art from the present description, the drawings and the attached claims, may be combined with other features or groups of features disclosed here, even if concretely these features have only been described in relation to other determined features, both individually and in arbitrary combinations, provided that this has not been expressly excluded or that technical circumstances make such combinations impossible or devoid of meaning.

Throughout the text of the present application, “fixed subassembly” has been used to refer to a subassembly that constitutes a fixed coordinate system for the rotation of the movable subassembly. Those skilled in the art will have understood that this subassembly is itself required to move relative to the body of the vehicle, depending on the geometry of the suspension interposed between the body of the vehicle and the fixed subassembly.