Patent Publication Number: US-2021170788-A1

Title: Hub bearing constant velocity joint

Description:
CROSS REFERENCE OF RELATED APPLICATION 
     This application is based on and claims priority to Italian Application No. 102019000023208, filed Dec. 6, 2019, under 35 U.S.C. § 119, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The subject matter of this disclosure is related constant velocity joint assemblies, hub bearing units having constant velocity joints, and for vehicles having such hub bearing units. 
     PRIOR ART 
     In vehicles that make use of wheel hub bearings a reduction of the weight of vehicle components is a general requirement associated with reduction of emissions and electrification. It is also a way of obtaining a reduction in the costs owing to the smaller amount of material to be used for manufacture. One way of achieving this aim is to redesign interfaces with surrounding components. 
     In the driving wheels of vehicles, especially front-drive vehicles, the interface between hub bearing unit, known by the abbreviation HBU, and the associated constant velocity joint, known by the abbreviation CVJ, must correctly transfer the torque between the two components as a primary function. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described with reference to the accompanying drawings which illustrate some non-limiting examples of embodiment thereof, in which: 
         FIG. 1  shows schematically in an orthogonal projection an elevation side view, cross-sectioned along a diametral radial plane, of a hub bearing/constant velocity joint assembly provided in accordance with this disclosure; and 
         FIGS. 2 to 5  show in schematic view aspects in accordance with this disclosure. 
         FIG. 6  illustrates a method in accordance with this disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     . In some arrangements a coupling element is used to impart a prestress to rings and associated rolling bodies of an HBU. The forced combination of these components is however not favourably viewed by the market owing to a number of drawbacks. Solutions are divided into two categories: those which transmit only the torque and those which impart and maintain the prestress in an HBU. In the first case an HBU is generally “self-prestressed”, for example by means of a cold deformation process. The assembly and the holding together of the two parts is generally performed by means of screw connections, for example using a CVJ having a splined stem which is inserted inside a central hole of a flanged inner ring (also known by the abbreviation “FIR”) of a hub bearing and which has a threaded end section onto which a nut is screwed. Said nut may be locked onto a flat region on the outer side of the FIR. Another known solution consists of a CVJ with a shorter stem, or without a stem, but with a threaded hole in its axially central portion. A screw is then introduced on an outer side and used to lock the CVJ against the HBU. In both cases, torque is transmitted by means an axial splined joint at an interface between a stem and a central hole of an FIR or, in a smaller number of cases, by a front splined coupling between a radially outer component or “bell member” of the CVJ or FIR of the HBU. 
     These solutions however involve the presence of a mechanical component (screw or stem or a combination of the two) which must occupy the entire axial length of the assembly, limiting moreover the length of the splined coupling on the stem. 
     US2003064817A1 describes a connection between HBU and CVJ in which torque is transmitted using an axial splined coupling between flanged inner ring of a rolling bearing (or hub bearing unit) and bell member of a CVJ, which has an associated central hole; the two parts are clamped together by a screw element which engages with a threading formed radially on the inside of the FIR. A screw element must be positioned inside the hole of the bell member of the CVJ during the operation of assembly of the CVJ itself and must therefore be kept in position until the moment of connection with the HBU, while ensuring correct insertion of the splined coupling, something which is performed using a shoulder formed by an end part of the shaft of the constant velocity joint. A prestress on rings of an HBU is therefore adjusted by means of a clamping force of a screw element which has an actuating seat of the hex key type situated facing on the HBU side and therefore on the outboard side of the vehicle. 
     This solution involves provisioning a shaft of a constant velocity joint which is particularly long and which has an end facing a screw element having, like a head of a screw element housed inside a bell member of a CVJ, a special shape resulting in additional costs and mechanical machining operations as well as a greater axial volume. There remains moreover in any case a relatively high axial play between the screw element and the shoulder formed by the end of the shaft of the constant velocity joint, which may cause imprecise or difficult positioning of the splined coupling. 
     Assemblies in accordance with this disclosure incorporate a system for improved coupling and clamping of a constant velocity joint against a hub bearing include a rolling bearing that address the limitations described above. 
     With reference to  FIG. 1 , in it  1  denotes in its entirety a hub bearing/constant velocity joint for vehicles, the general structure of which is known. 
     The assembly  1  comprises a hub bearing unit  2 , known in its entirety and illustrated only partly for the sake of simplicity, and a constant velocity joint  3 , known as a whole, of which for the sake of simplicity only a shaft  4  and a—preferably bell-shaped—annular joint element  5  are shown, the latter being known as a whole and having, as can be seen in  FIG. 1 , respective raceways  6  for ball bearings (not shown) of the constant velocity joint  3  which are intended to transmit in a known manner the torque between the joint element  5  and the shaft  4 . 
     The assembly  1  comprises furthermore a clamping system  7  for keeping coupled together, as will be seen, the constant velocity joint  3  and the hub bearing unit  2 . 
     The hub bearing unit comprises a radially outer annular housing or ring  8 , defined in the example shown by an outer ring of a rolling bearing  9 , a radially inner, annular, flanged hub  10 , defined in the example shown by an inner ring of the rolling bearing  9  and provided at a first end  11  thereof with a flange  12  (known and only partly shown), said flange extending radially on the outside of the annular housing  8 , and a plurality of rolling bodies  13  arranged between the annular housing  8  and the hub  10  so as to make the hub  10  rotatable with respect to the annular housing  8  about a common axis of symmetry A of the hub  10  and the annular housing  8 . 
     In the non-limiting example shown, the rolling bodies  13  occupy a pair of respective raceways  14 , a first one being formed directly on the annular hub  10 , on the side where the flange  12  is located, and a second one being formed on a ring (also known as SIR) embedded in a cylindrical annular portion  16  of the hub  10  which is formed on the opposite side to the flange  12  and from which a second end  18  of the annular hub  10 , opposite to the end  11 , projects axially in cantilever fashion. 
     With reference also now to  FIG. 2 , which shows on a larger scale a detail of  FIG. 1 , the constant velocity joint  3 , as has been seen, comprises the radially outer, annular, joint element  5  which is configured to engage with the second end  18  of the annular hub  10  by means of an axial splined coupling  19  which is known and formed radially on the outside of the annular hub  10 . 
     The clamping system  7  comprises a screw element  20  in turn including a threaded stem  21  and a flange-shaped head  22 . 
     The flange-shaped head  22  extends radially on the outside from a first end  222  of the threaded stem  21  facing, during use, the annular joint element  5 . 
     The clamping system  7  further comprises a threaded section  23  of the annular hub  10 , which threaded section  23  is formed radially on the inside of the second end  18  of the hub  10  and is configured to engage with the threaded stem  21  of the screw element  20 . 
     The flange-shaped head  22  is instead configured to cooperate with an annular shoulder  24  of the annular joint element  5  formed inside the joint element  5  on the opposite side to the annular hub  10 . 
     The threaded stem  21  is also provided, on the side facing, during use, the annular hub  10 , with an actuating seat  25 , of the known type, for example of the hex key type, configured to cause rotation of the screw element  20  by using a tool (known and not shown for the sake of simplicity) on the side where the annular hub  10  is located and through the same. 
     In accordance with various embodiments, the clamping system further comprises an elastic ring  26  and at least one annular seat  27  for the elastic ring  26  which, in the non-limiting example shown in  FIGS. 1 and 2 , is formed entirely radially on the inside of the annular joint element  5 , in particular on a radially inner, cylindrical, side surface  28  which terminates against the shoulder  24 . 
     In accordance with various embodiments, the at least one annular seat  27  for the elastic ring  26  is configured so that the elastic ring  26 , when it is engaged with the annular seat  27 , as shown in  FIGS. 1 and 2 , keeps the flange-shaped head  22  in cooperation with the annular shoulder  24 . 
     In particular, the at least one annular seat  27  is configured so that the elastic ring engages with/inside it with a predefined axial play G which in  FIG. 2  is shown enlarged and out-of-scale only for exemplary purposes. 
     Even more particularly, the at least one annular seat  27  is configured so that the elastic ring  26  engages inside/with it with an axial play G of at least 10 hundredths of a millimetre and which, preferably, is not more than 20 hundredths of a millimetre, i.e. with an axial play G which, remaining within these orders of magnitude, may be defined in the context of the present disclosure as “minimal”. 
     The annular seat  27  is also configured so that the elastic ring  26  engages inside/with it also with a predefined axial play so as to allow in a known manner the operation of the elastic ring  26  which may thus be inserted inside/disengaged from the annular seat  27  as required, by means of a special known tool not shown for the sake of simplicity. 
     In the embodiment shown in  FIGS. 1 and 2 , finally, the clamping system  7  includes a single annular seat  27  for the elastic ring  26 , which seat  27  is formed radially on the inside of the annular joint element  5 , in the proximity of the annular shoulder  24 , so that the elastic ring  26 , when it is engaged with the single annular seat  27 , tightly locks the flange-shaped head  22  between the same elastic ring  26  and the radially inner annular shoulder  24  of the annular joint element  5 . 
     With reference now to  FIGS. 3 to 5 , where details similar or identical to those already described are indicated for the sake of simplicity with the same numbers, the at least one annular seat  27  for the elastic ring  26 , instead of being single and formed only on the joint element  5 , may be double, so that the elastic ring  26  engages simultaneously both the joint element  5  and the screw element  20  instead of forming simply a shoulder element for the screw element  20 , as shown in  FIGS. 1 and 2 , where the elastic ring  26  faces the shoulder  24  and is axially spaced therefrom by a distance substantially equal to the thickness, measured in the axial direction, of the flange-shaped head  22 . 
     According to the embodiments shown in  FIGS. 3 to 5 , therefore, a first annular seat  27  is present, formed radially on the inside of the joint element  5 , but a second annular element is also present, formed radially on the outside of the flange-shaped head  22 , along a radially outer peripheral edge  29  of the flange-shaped head  22 . 
     In accordance with that shown in  FIGS. 3 and 5 , where  1   b  and  1   d  indicate two alternative embodiments of the assembly  1  shown in  FIGS. 1 and 2 , the clamping system  7  includes a first annular seat  27  formed on the side surface  28  and a second annular seat  30  for the elastic ring  26 . 
     The seats  27  and  30  are formed facing each other, i.e. the first seat  27  is formed radially on the inside of the annular joint element  5 , in the proximity of the annular shoulder  24 , and the second seat  30  is formed radially on the outside of the flange-shaped head  22 , along the peripheral edge  28 ; according to these embodiments, the elastic ring  26  is configured to engage simultaneously both of the seats  27  and  30 , with its radially outer edge and with its radially inner edge, respectively. 
     According to the embodiment  1  ( FIGS. 1 and 2 ) and  1   b  ( FIG. 3 ), the elastic ring  26  has a radial cross-section with a quadrangular shape. 
     Instead, according to the embodiment  1   d , the elastic ring  26  has a radial cross-section with a circular shape, and therefore the elastic ring  26  has a toroidal shape. 
     In the embodiments  1   b ,  1   d , in order to be able to allow, as will be seen, the assembly of the constant velocity joint  3 /hub bearing  2 , the radial depth of the annular seat  27  is less than the thickness or radial widthwise extension (i.e. cross-section) of the elastic ring  26 , while the radial depth of the annular seat  30  must be greater than the thickness or radial widthwise extension (i.e. cross-section) of the elastic ring  26 . 
     According to the embodiment  1   c  shown in  FIG. 4 , finally, the second annular seat  30  for the elastic ring  26  is formed on a front surface  31  of the flange-shaped head  22 , said surface  31  being situated facing, during use, on the opposite side to the annular hub  10 ; the seat  30  extends radially, moreover, as far as the radially outer peripheral edge  29 , so as to delimit a step  32  thereon. 
     In accordance with various embodiments, in all the embodiments  1 ,  1   b ,  1   c ,  1   d  described, the axial splined coupling  19  is formed radially on the outside of the second end  18  of the annular hub  10 , axially offset towards the annular joint element  5  with respect to the threaded section  23  of the annular hub  10  formed radially on the inside of the second end  18  of the annular hub  10 . 
     In this way, in accordance with various embodiments, at last part of the splined coupling  19  protrudes axially in cantilever fashion towards the annular joint element  5  with respect to threaded section  23 . 
     From that described hitherto, finally, it is clear that the subject matter of this disclosure relates also to a method for manufacturing a hub bearing/constant velocity joint assembly for vehicles such as the assemblies  1 ,  1   b ,  1   c ,  1   d  described, comprising the steps below illustrated in  FIG. 6 . 
     A first step  1001  for providing a hub bearing unit  2  comprising a radially outer annular housing  8 , a radially inner annular hub ( 10 ) provided, at its first end  11 , with a flange  12  that radially extends on the outside of the annular housing  8 , and a plurality of rolling bodies  13  arranged between the annular housing  8  and the hub  10  in order to make the hub  10  rotatable with respect to the annular housing  8  about a common axis of symmetry A. 
     A second step  1002  for providing a constant velocity joint  3  in a disassembled (i.e. dismounted) configuration and comprising a shaft  4 , rolling bodies, known and not shown for simpler illustration, and an annular joint element  5  radially on the outside with respect to the shaft  4 , configured to engage with a second end  18  of the annular hub  10 , opposite to the first end  11 , by means of an axial splined coupling  19  formed radially on the outside of the annular hub  10 . 
     A third step  1003  for providing a screw element  20  including a threaded stem  21  and a flange-shaped head  22  that extends radially on the outside from a first end  222  of the threaded stem  21 ; during this step the threaded stem  21  is provided, on the opposite side to the flange-shaped head  22 , with an actuating seat  25  configured for rotation of the screw element  20 . 
     A fourth step  1004  for forming, radially on the inside of the second end  18  of the annular hub  10 , a threaded section  23  configured to engage with the threaded stem  21  of the screw element  20 . 
     A fifth step  1005  for forming, on the inside of the annular joint element  5 , an annular shoulder  24  configured to cooperate, during use, with the flange-shaped head  22  of the screw element  20  on the opposite side to the annular hub  10 . 
     A sixth step  1006  for inserting, according to a first aspect of the invention, the screw element  20  inside the annular joint element  5  on the side where the threaded stem  21  is located and until the flange-shaped head  22  is brought into abutment against the annular shoulder  24 , causing at least part of the threaded stem  21  of the screw element  20  to axially project out of the annular joint element  5 , in cantilever fashion, through an axial through-hole  33  of the annular joint element  5  configured to be facing, during use, the annular hub  10  and to cooperate angularly with the splined coupling  19 . 
     A seventh step  1007  for axially locking, according to an aspect of the invention, the screw element  20  in abutment against the annular shoulder  24  with minimum axial play, by means of the insertion inside the annular joint element  5  of an elastic ring  26  which is snap-fitted into at least one annular seat  27  and/or  30  formed beforehand radially on the inside of the annular joint element  5  and/or radially on the outside of the flange-shaped head  22 , along a radially outer peripheral edge  29  of the flange-shaped head  22 . 
     An eighth step  1008  for completely assembling, according to a further aspect of the invention, the constant velocity joint  3 , for example by inserting the shaft  4  inside the joint element  5  and engaging the raceways  6  and the shaft  4 , in a known manner, with suitable rolling bodies, not shown. 
     A ninth step  1009  for initially mounting, by means of pushing in an axial direction, the annular joint element  5  onto the axial splined coupling  19  of the second end  18  of the annular hub  10 , inserting it there above the suitably shaped hole  33 , so as to start angular coupling of the constant velocity joint  3  together with the annular hub  10 . 
     A tenth step  1010  in which, using a tool on the side where the annular hub  10  is located and through the same, rotating the screw element  20  so as to progressively screw the threaded stem  21  onto the threaded section  23  of the second end  18  of the annular hub  18 , so as to progressively complete the angular coupling together of the constant velocity joint  3  and the annular hub  10  inserting the splined coupling  19  of the latter completely inside the annular joint element  5 . 
     An eleventh  1011  and final step for continuing to apply a rotational torque to the screw element  20  until the flange-shaped head  22  is pushed against the axial annular shoulder  24  with an axial force such as to obtain predefined prestressing of the rolling bodies  13  of the hub bearing unit  2 , this being made possible by the fact that the head  22  which pushes against the shoulder  24  presses the joint element  5  against the ring  15 . 
     On the basis of that described above it is evident that the screw element, contrary to the situation in the present state of the art, is kept in position already during assembly and then during transportation and handling of the constant velocity joint  3  by means of the elastic ring  26  which engages inside a groove defined by the annular seat  27  in the inner surface of the bell member of the constant velocity joint  3 , defined by the joint element  5 , simplifying the assembly and the design of the constant velocity joint  3 , the components of which must no longer have special shapes as in the prior art, with a corresponding reduction in costs. 
     The internal part of the screw element  20  is blind so as to prevent any penetration of water or dirt inside the constant velocity joint and potential loss of grease or vapour. 
     Moreover, by introducing the stop function due to the elastic ring  26 , the screw element  20  may be easily positioned inside the seat of the hub  10  when it is assembled with the constant velocity joint  3  and these parts kept in position during the subsequent operations in the assembly chain. This also ensures a much smaller displacement of the screw element  20  during the combination with the hub bearing unit  2 , which is very important during the coupling operation. During this step, in fact, initially engagement of the splined coupling  19  should be obtained in order to ensure correct alignment and rapid engagement of the screw  20  inside the thread  23 , reducing the risk of incorrect insertion. This also ensures that any position of the shaft  4  may be taken into account in order to solve any type of problem which may be encountered in the very limited space of the area of the upright forming part of the vehicle suspension (both during initial installation and during post-sales assistance). 
     The embodiment  1   b  is also effective during the assembly of the constant velocity joint, provided that the assembly of the elastic ring  26  may be initially performed on the head  22  of the screw element  20  and therefore in an open environment and without any force during positioning. The screw  20  with the assembled ring  26  is then easily pushed inside the joint element  5  until the ring  26  engages inside the groove  27 . 
     An object of the present disclosure is to provide a hub bearing/constant velocity joint assembly for vehicles with a system for improved coupling and clamping of the constant velocity joint together with the hub bearing, which does not have the drawbacks of the prior art and which, in particular is compact, reliable and able to be easily coupled together in a very precise manner. 
     An object of this disclosure is also to provide a method for manufacturing in a simple and reliable manner a hub bearing/constant velocity joint for vehicles. 
     On the basis of this disclosure, therefore, a bearing unit/constant velocity joint assembly for vehicles and an associated manufacturing method are described, these having the characteristic features indicated in the attached claims. 
     All the objects of the invention are therefore achieved.