Patent Publication Number: US-2021170790-A1

Title: Suspension unit for a vehicle

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to a suspension assembly for vehicles comprising a hub bearing unit and a suspension upright or knuckle, the assembly including an innovative connection system between the stationary ring, usually the outer ring of a rolling bearing included in, or forming, the hub bearing unit, and a suspension upright or knuckle made of light alloy. 
     PRIOR ART 
     In existing suspension assemblies, the connection of the hub bearing unit to the suspension upright or knuckle is usually made by means of a screw connection, normally using three or four screws, in which the outer ring of the rolling bearing forming part of the hub bearing unit, usually stationary, is provided towards the suspension upright with a flange or a plurality of lugs (at least four) which is or are engaged by the screws, and are then fixed in suitable holes in the suspension upright. 
     The radial extensions formed by the flange or by the lugs and screws increase the overall weight of the suspension assembly. 
     A different connection system was in use previously, consisting in a forced coupling, that is to say an interference coupling, between a radially outer lateral surface of the outer ring of the bearing forming part of the hub bearing unit and a cylindrical through hole formed through the suspension upright. Axial retention was provided by means of shoulders formed on the upright and/or resilient rings that were inserted to extend around the outer ring. 
     However, such a solution, if applied to suspension assemblies having an upright made of light alloy, may be affected by the differential thermal expansion between the outer ring of the bearing and the upright, as a result of which axial and circumferential displacements may occur, leading to the generation of noise, local wear phenomena, or actual deformation. This technical problem can be overcome by the use of spring devices, which again entail an increase in weight and complicated assembly operations, as well as additional costs. Furthermore, on thin bearing rings, the cavities for the articulation of the resilient rings create weaknesses and may therefore promote undesired elastic deformations or, in extreme cases, crack formation. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The object of the present invention is to provide a suspension assembly for vehicles, including a connection system between a hub bearing unit and a suspension upright or knuckle forming part of the assembly, which is free of the drawbacks of the prior art while being reliable, economical, and easily assembled. 
     According to the invention, therefore, a suspension assembly for vehicles is provided, including a suspension upright or knuckle and a hub bearing unit, together with an associated connection system and hub bearing unit, having the characteristics stated in the attached claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described with reference to the attached drawings, which show a non-limiting example of its embodiment, in which: 
         FIG. 1  shows schematically a view in elevation and in longitudinal section of a vehicle suspension assembly including a hub bearing unit, a suspension upright and an associated connection system made according to the invention; 
         FIG. 2  shows schematically a three-quarter perspective view of the hub bearing unit of the suspension assembly of  FIG. 1 , provided with the connection system according to the invention; 
         FIG. 3  shows schematically, on an enlarged scale and with parts removed for simplicity, a three-quarter perspective front and sectional view of a detail of the suspension assembly of  FIG. 1 ; and 
         FIG. 4  shows schematically, on a reduced scale, a three-quarter perspective front view of part of the vehicle suspension assembly of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIGS. 1 and 4 , in these figures the number  1  indicates the whole of a vehicle suspension assembly, comprising a hub bearing unit  2 , a suspension upright or knuckle  3  for the hub bearing unit  2 , and a connection system  4  between the hub bearing unit  2  and the suspension upright or knuckle  3 . 
     The suspension upright or knuckle  3  has a known type of overall structure, and, according to an aspect of the invention, is preferably made of a light alloy by moulding or casting. 
     The suspension upright or knuckle  3  comprises a reception seat  5  for receiving, as will be seen, a radially outer ring or element  6  of the hub bearing unit  2 . 
     In particular, the hub bearing unit  2  is formed, in the illustrated non-limiting example, by a rolling bearing comprising the outer ring  6 , a flanged inner ring  7  and a plurality of rolling bodies  8 , consisting of two rings of balls for example, interposed between the rings  6  and  7  to make the ring  7  rotatable relative to the ring  6 . 
     The ring  7  forms a radially inner element of the hub bearing unit  2 , is housed coaxially within the radially outer ring or element  6 , and has a first end  9  and a second end  10  opposite the end  9 . 
     The end  10 , which in use faces in the opposite direction from the suspension upright or knuckle  3 , is provided with an annular flange  11 , which extends in cantilever fashion radially to the outside of both the radially inner ring  7  and the radially outer ring  6 . 
     The flange  11  is provided with a plurality of threaded holes  12  into which corresponding captive screws, known and not illustrated for simplicity, may be fixed, by means of which screws a vehicle wheel (known and not illustrated for simplicity) is fixed, in use, to the flange  11 . 
     At the position of the holes  12 , the flange  11  is provided, on its rear wall  13  facing the suspension upright or knuckle  3 , with corresponding radial strengthening spokes  14  ( FIG. 2 ), formed integrally in one piece with the flange  11 . 
     According to an aspect of the invention, and with additional reference to  FIGS. 2 to 4 , the connection system  4  comprises a radially outer lateral cylindrical surface  16  of the radially outer ring or element  6  of the hub bearing unit  2 , configured to couple by interference fit with a radially inner lateral cylindrical surface  18  of the reception seat  5 . 
     The connection system  4  further comprises a lug  19  or preferably a single pair of lugs  19 , or, according to a possible variant not illustrated for simplicity, three lugs  19  that protrude radially in a cantilever fashion from a front rim  20  of the radially outer ring or element  6  of the hub bearing unit  2 . 
     The front rim  20  is opposite the suspension upright or knuckle  3 , and each lug  19  is provided with an axial through hole  21 . 
     It should be noted that, by contrast with some prior art embodiments, the lugs  19  face in an opposite direction from the end  9  of the inner ring  7 ; in other words, they are formed on the ring  6  towards the end  10 , that is to say towards the same end or on the same side of the flange  11  of the ring  7 , and therefore on the opposite side from an end  22  of the ring  6  which is opposite the rim  20  and faces in the direction of introduction of the ring  6  into the seat  5 , which is cylindrical. 
     According to a further aspect of the invention, the connection system  4  also comprises a frontal surface  23  of the suspension upright or knuckle  3  configured to receive the single lug  19  or the plurality (two or more) of lugs  19  in axial abutment, that is to say in an interacting way in contact. 
     Finally, the connection system  4  comprises at least one screw  24 , and preferably as many screws  24  as there are lugs  19  fitted, mounted in a through manner through the axial holes  21  of the lugs  19 , each screw being screwed into a respective threaded hole  25 , or preferably a pair or even a plurality of threaded holes  25 , formed in the suspension upright or knuckle  3  at the frontal surface  23  of the latter. 
     It should be noted that, by contrast with various prior art solutions, the screws  24  are simple flat head screws, which bear on a flat end surface  15  of respective seats for the heads of the screws  19 , defined by a larger-diameter portion of the through holes  21 , this portion facing towards the flange  11 . Conversely, in the prior art use is commonly made of spherical head screws, the head of each screw bearing on a spherical seat, the machining of which is rather costly and is no longer necessary in the solution according to the invention, thus providing savings in terms of cost, weight and overall dimensions. 
     According to a further aspect of the invention, the radially outer ring or element  6  of the hub bearing unit  2  is fitted at its end  22 , opposite the lugs  19 , into the seat  5  of the suspension upright or knuckle  3  for a substantial part of the axial length of the outer ring  6  and therefore of the lateral surface  16  and of the radially inner lateral surface  18  of the cylindrical seat  5 . 
     Here and subsequently, “substantial part” is taken to mean a part having a length equal to at least two thirds of the overall axial length/extension of the outer ring  6  and the seat  5  respectively. 
     The two lugs  19  of the single pair of fixing lugs, with which the outer ring  6  is provided in the illustrated non-limiting example, protrude radially in cantilever fashion from the radially outer lateral cylindrical surface  16  of the radially outer ring or element  6  of the hub bearing unit  2 , and interact by abutment with the frontal surface  23  of the suspension upright or knuckle  3 . 
     The surface  23  faces in the opposite direction from the reception seat  5  and is preferably shaped as an annular surface. 
     The two lugs  19  of the single pair of lugs with which the outer ring  6  is provided in the illustrated non-limiting example, together with the corresponding two threaded holes  25  of suspension upright or knuckle  3 , are, according to a further aspect of the invention, positioned to be offset in the circumferential direction by an angle a of at least 100°. 
     Preferably, the two lugs  19  and the corresponding two holes  25  are positioned to be offset from one another circumferentially by an angle α of 130°, or are positioned to be diametrically opposed, being offset circumferentially by angle α of 180°. 
     If there are three of the lugs  19 , these may preferably be positioned to be uniformly spaced, at 120° from one another. 
     The solution or variant which includes the presence of three lugs  19  has the advantage of better handling of the workpiece during forging: in particular, when high-speed horizontal presses are used, the grip on a workpiece with only two lugs  19 , which are also of small size, may give rise to problems because of the possible rotation of the workpiece. The presence of the third lug helps to enable the workpiece to be gripped and manoeuvred more securely in a horizontal press. The solution with three lugs may therefore be preferable, even if the third lug may be superfluous simply as regards the securing of the ring  6  to the suspension upright or knuckle  3 . 
     The radially inner ring or element  7  housed coaxially within the radially outer ring or element  6 , with respect to which it is relatively rotatable, is provided with the flange  11  at its end  10 , which faces in the opposite direction from the radially outer ring or element  6 . 
     Additionally, the flange  11  extends radially in cantilever fashion in front of the lugs  19  and is provided, in addition to the holes  12 , with at least a pair of, and preferably four, axial through holes  26 , preferably spaced apart from one another symmetrically in the circumferential direction and configured for being positioned in use, selectively or simultaneously, in front of the lugs  19  to all access for manoeuvring the screws  24 . 
     It is evident from the above description that the invention also relates to a connection system  4  between a hub bearing unit  2  and a suspension upright or knuckle  3 , comprising:
         a radially outer lateral cylindrical surface  16  of a radially outer ring or element  6  of the hub bearing unit  2 , configured to couple by interference fit with a radially inner lateral cylindrical surface  18  of a reception seat  5  of the suspension upright or knuckle  3 ;   at least one lug  19 , or preferably a plurality (two or three) of lugs  19  that protrude radially in cantilever fashion from a front rim  20  of the radially outer ring or element  6  opposite to the suspension upright or knuckle  3 , each lug  19  being provided with an axial through hole  21 ;   a frontal surface  23  of the suspension upright or knuckle  3 , configured to receive the lugs  19  in axial abutment; and   screws  24  mounted in a through manner through the axial holes  21  of the lugs  19  and screwed into respective threaded holes  25  formed in the suspension upright or knuckle  3 , around and radially outside the cylindrical seat  5 , on the frontal surface  23  of the suspension upright or knuckle  3 .       

     As described above, in this connection system  4  the frontal surface  23  of the suspension upright or knuckle  3  is annular and the lugs  19 , if they are two in number, are positioned to be circumferentially offset from one another by an angle of at least 100° and are preferably diametrically opposite one another, being circumferentially offset by an angle a of 180°. 
     In the connection system  4  according to the invention, finally, the hub bearing unit  2 , if provided with a flanged radially inner ring or element  7 , as in the illustrated non-limiting example, must have the flange  11  of the ring or element provided at least a pair of, and preferably four, axial through holes  26  configured to be positioned, in use, in front of the lugs  19  to provide access for manoeuvring the screws  24 . 
     The invention therefore relates to a connection by means of screws, used in a minimal number and with the lugs  19  positioned differently from the prior art, combined with a specific design of the upright or knuckle  3  which is coupled to the outer ring  6 , which is stationary in use, by means of a cylindrical radial interference coupling formed by the two lateral surfaces  16  and  18 . 
     The combined connection using a forced coupling and screws enables the weight to be reduced, not only because the outer ring  6  is lighter than the prior art flanged rings, but also because a smaller number of screws is used, and these screws are, most notably, smaller and lighter than the screws used in the prior art. 
     Additionally, the cylindrical coupling, forced in a press with a specific insertion pressure (which, expressed as an interference measurement, requires a forced coupling of 100 to 180 microns) provides safe operation up to high temperatures, by compensating for the expansion of the seat  5  and maintaining adequate rigidity. At very high temperatures (180° C.), the cylindrical adhesion still contributes to the rigidity, but the axial retention is supported by the screws  24 . 
     With reference to prior art assemblies, the tightening operation is simpler and faster, because only one or a few (two or three) screws are required. This simplicity of assembly results in a lower cost and weight, owing to the better use of the material. 
     By combining a suitable coupling interference, a suitable axial coupling length between the surfaces  16  and  18 , and a suitable size of the screws  24 , it is possible to meet all the required performance levels during operation at high and low temperature. The screw connection prevents relative rotation and axial movement between the upright or knuckle  3  and the outer ring  6 , thus preventing noise generation, surface wear phenomena, and premature failure. Additionally, the retention system according to the invention has better performance in terms of rigidity at high loads, by comparison with the known solutions in which the outer ring is connected to the upright by means of a flange and screws, commonly with spherical heads. 
     All the objects of the invention are therefore achieved.