Abstract:
This invention relates to a vehicle wheel hub and brake rotor including a wheel hub portion formed from a first material and a brake rotor portion formed from a second material and joined to the wheel hub flange during an in situ casting process. The method for producing the vehicle wheel hub and brake rotor of the present invention includes the steps of (a) providing wheel hub portion formed from a first material and including a radially outwardly extending wheel hub flange; (b) placing the wheel hub portion in a mold; and (c) casting a brake rotor portion formed from a second material in situ therewith, the brake rotor portion including a flange which is operatively joined to the wheel hub flange during the in situ casting process to thereby join the wheel hub portion to the brake rotor portion.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates in general to vehicle wheel hubs and vehicle brake rotors and in particular to an improved structure for such a vehicle wheel hub and brake rotor and method for producing the same. 
     It is known to cast a rotatable brake component (e.g., a rotor or drum) with an integral hub portion. A conventional integral hub and rotor includes an axially extending hub, a radially extending mounting surface, and a radially extending outer disc which can be integrally cast of the same material as one-piece during a casting operation. The hub includes a centrally located bore formed therein, and a plurality of equally spaced lug bolt receiving holes are formed in the mounting surface circumferentially about the bore. The outer disc defines a pair of brake friction plates having opposed braking surfaces which are typically machined to be parallel to one another and perpendicular to the rotor axis. The integral hub and rotor defines an inner bearing seat for receiving a bearing unit, such as for example, a preassembled cartridge type of bearing unit. The cartridge bearing unit can either be a pregreased sealed-for-life cartridge bearing, or of the type having a pair of bearing elements, either ball bearings or tapered roller bearings, disposed between an inner bearing race or cup and an outer bearing race or cup. 
     U.S. Pat. No. 5,988,324 to Bertetti et al. discloses a wheel hub bearing unit of a two-piece design. As disclosed the Bertetti et al. patent, the wheel hub bearing unit includes a bearing flange member which is secured to a flange of a disc or drum member by a suitable cold forming process (e.g., punching, pinching, rolling). 
     SUMMARY OF THE INVENTION 
     This invention relates to a vehicle wheel hub and brake rotor including a wheel hub portion formed from a first material and a brake rotor portion formed from a second material and joined to the wheel hub flange during an in situ casting process. The method for producing the vehicle wheel hub and brake rotor of the present invention includes the steps of (a) providing wheel hub portion formed from a first material and including a radially outwardly extending wheel hub flange; (b) placing the wheel hub portion in a mold; and (c) casting a brake rotor portion formed from a second material in situ therewith, the brake rotor portion including a flange which is operatively joined to the wheel hub flange during the in situ casting process to thereby join the wheel hub portion to the brake rotor portion. 
     Other advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view of a first embodiment of a vehicle wheel hub and brake rotor in accordance with the present invention. 
     FIG. 2 is a sectional view of the wheel hub portion of the wheel hub and brake rotor illustrated in FIG.  1 . 
     FIG. 3 is a side plan view of the wheel hub portion in the direction of line  3 — 3  of FIG.  2 . 
     FIG. 4 is a sectional view of a portion of a second embodiment of a vehicle wheel hub and brake rotor in accordance with the present invention. 
     FIG. 5 is a sectional view of a portion of a third embodiment of a vehicle wheel hub and brake rotor in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to FIG. 1, there is illustrated a first embodiment of a vehicle wheel hub and brake rotor, indicated generally at  10 , in accordance with this invention. The illustrated vehicle wheel hub and brake rotor  10  is associated with a driven wheel (not shown) of a vehicle. The illustrated vehicle wheel hub and brake disc  10  is designed to work with an “internal ring rotation” type of bearing unit. The term “internal ring rotation” as used herein means that the bearing unit inner race is used to rotatably support the associated vehicle wheel hub and the bearing unit outer race is fixed (i.e., does not rotate) during vehicle operation. Although this invention will be described and illustrated in conjunction with the particular vehicle wheel hub and brake rotor  10  disclosed herein, it will be appreciated that this invention may be used in conjunction with other vehicle wheel hub and brake rotor structures. For example, the vehicle wheel hub and brake rotor  10  of this invention can be used in a non-driven wheel application and in conjunction with a driven/non-driven outer ring rotation type of bearing unit. 
     The vehicle wheel hub and brake rotor  10  includes a wheel hub portion  12  and a brake rotor portion  14  which are joined together in a manner to be discussed below in accordance with the present invention. The vehicle wheel hub and brake rotor  10  defines a longitudinal axis X. 
     The wheel hub portion  12  is preferably formed from steel, forged or cast, and includes a generally stepped body having an opened inboard end  20 , an opened outboard end  22 , and a generally axially extending main body  24 . The main body  24  of the wheel hub portion  12  is provided with a radially outwardly extending flange  26  and defines an inner race having an outer surface  28 . The outer surface  28  of the inner race of the wheel hub portion  12  defines a bearing seat for receiving a bearing unit  30  (the bearing unit  30  shown in phantom in FIG.  1 ). Alternatively, the wheel hub portion  12  can be formed from other materials, such as for example, ductile iron. 
     In the illustrated embodiment, the bearing unit  30  includes two rows of ball bearings  30 A and  30 B, an outer race  30 C, and a pressed-on inner race  30 D for supporting the inboard row of ball bearings  30 A. The outer race  30 C includes a radially outwardly extending flange  30 E which is provided with a plurality of circumferentially spaced mounting bolt holes  30 F formed therein (only one of such mounting bolt receiving holes  30 F is illustrated in FIG.  4 ). A mounting bolt (not shown) is disposed in each of the mounting bolt receiving holes  30 F to secure the outer race  30 C of the bearing unit  54  to a non-rotatable component of the vehicle, such as the steering knuckle (not shown), so as to rotatably support the vehicle wheel hub and brake rotor  10  relative thereto. 
     Alternatively, the bearing unit  30  can be other than illustrated if so desired. For example, bearing unit can include tapered bearings (not shown), and can include an inner race which is disposed on the outer surface  28  of the wheel hub portion  12 . In the latter design, the wheel hub portion  12  would not define an inner race for the outboard bearings  30 B of the bearing unit  30  as illustrated in the embodiment shown in FIG. 1, but would define a surface  60  for receiving an inner race portion  62  of the associated bearing unit (as shown in FIG.  5 ). 
     The flange  26  of the wheel hub portion  12  includes a plurality of circumferentially spaced wheel stud receiving holes  26 A formed therein (five of such wheel stud receiving holes  26 A illustrated in FIG.  3 ). A lug bolt  32  (shown in phantom in FIG. 1) is disposed in each of the wheel stud receiving holes  26 A to secure a vehicle wheel (not shown) to the vehicle wheel hub and brake disc  10  for rotation therewith. The opened outboard end  22  of the wheel hub portion  12  is adapted to receive a nut (not shown) which is installed on a threaded end of a shaft to secure and load the bearing unit  30  in a known manner. Alternatively, in the case of a non-driven wheel hub, a dust cover or other suitable protective cover (not shown) can be installed on the opened outboard end  22  to prevent dirt, mud, water, and other debris from entering into the interior of the wheel hub portion  12  therethrough. Alternatively, other methods can be used to secure and load the bearing unit  30 . For example, the end  20  of the wheel hub portion  12  can be deformed over the race of the bearing unit  30  (as shown in phantom at  20 ′ in FIG. 1) during a metal forming process. 
     The wheel hub portion  12  is provided with a bore  34  extending therethrough from the opened inboard end  20  to the opened outboard end  22 . In the illustrated embodiment, the bore  34  includes internal splines  36  provided along a portion thereof. The internal splines  36  of the wheel hub portion  12  are adapted to matingly receive external splines provided on an outer surface of an associated drive member, such as for example, an axle shaft or drive shaft (not shown). Alternatively, the structure of the wheel hub portion  12  can be other than illustrated if so desired. For example, the wheel hub portion  12  can be of a solid design (i.e., no inner bore) and/or can have the bore  34  but not include the internal splines  36  (as shown in FIG.  5 ). 
     As shown in FIGS. 1 and 2, the flange  26  of the wheel hub portion  12  is provided with a plurality of outwardly extending tabs or protuberances  40  spaced circumferentially around an outer surface  42  thereof (ten of such tabs  40  illustrated in FIG.  3 ). In the illustrated embodiment, each of the tabs  40  is located generally intermediate the outer surface  42  in approximately the center thereof. Alternatively, the spacing, configuration and/or location of the tabs  40  can be other than illustrated if so desired. As will be discussed below, the tabs  40  are operative to join the wheel hub portion  12  and the brake disc portion  14  together during the manufacture of the vehicle wheel hub and brake rotor  10 . Also, other means can be used to join the wheel hub portion  12  and the brake disc portion  14  together. For example, as shown in FIG. 4, the outer surface  42  of the wheel hub portion  12  can be provided with a plurality of recesses  44  (only one of such recesses  44  are shown in FIG.  4 ), that would be filled with material of the brake rotor portion  14  during the casting of the brake rotor, or as shown in FIG. 5, a pin-link member  46  could be inserted into corresponding apertures  48  formed in the hub flange  26  so that during the casting of the brake rotor  14 , the pin members  46  are effective to join the wheel hub portion  12  and the brake rotor portion  14  together. 
     The brake rotor  14  is preferably formed from a castable material, such as for example, iron, aluminum or alloys thereof. As will be discussed below, the brake rotor  14  is joined to the wheel hub portion  12  during a casting process. As shown in this embodiment, the brake rotor portion  14  of the vehicle wheel hub and brake rotor  10  is a vented type of brake rotor and includes a pair of brake friction plates  50  and  52 . 
     The brake friction plates  50  and  52  are spaced apart and connected together by fins or ribs  54 . The brake friction plate  50  defines an inboard brake friction plate and includes an outer surface  50 A. The brake friction plate  52  defines an outboard brake friction plate and includes an outer surface  52 A, which is generally parallel to the outer surface  50 A. The brake friction plate  52  includes a flange or transition portion  56  which is operative to connect the brake friction plate  52 , and therefore the brake friction plate  50 , to the flange  26  of the wheel hub portion  12 . In the illustrated embodiment, the flange  56  is a generally radially inwardly extending flange; however, the flange  56  can be other than illustrated if so desired. Also, the structure of the brake rotor  14  can be other than illustrated if so desired. 
     One advantage of the vehicle wheel hub and brake rotor  10  of the present invention is that the wheel hub portion  12  can be made of a material which is sufficiently strong to form the splines  36  in a driven wheel application and/or to support vehicle loads. 
     In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been described and illustrated in its preferred embodiments. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.