Land vehicles: wheels and axles – Wheel – Hub
Reexamination Certificate
1999-08-05
2002-04-02
Morano, S. Joseph (Department: 3617)
Land vehicles: wheels and axles
Wheel
Hub
C384S544000, C029S898090, C188S2180XL
Reexamination Certificate
active
06364426
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates in general to vehicle brakes and in particular to an improved vehicle wheel hub and bearing unit assembly and method for producing the same.
A conventional vehicle wheel hub and bearing unit assembly associated with a driven front wheel of a vehicle includes a wheel hub and a bearing unit assembly. The wheel hub includes a generally stepped main body having an opened inboard end, an opened outboard end, and a generally axially extending main body. The main body of the wheel hub includes internal splines for receiving mating external splines provided on an axle for rotatably connecting the wheel hub to the axle for rotation therewith. The main body of the wheel hub also includes a generally radially outwardly extending flange having a plurality of circumferentially spaced apart stud receiving holes formed therein. The stud receiving holes receive wheel studs and nuts for securing a brake rotor of a disc brake assembly and a vehicle wheel to the flange of the wheel hub for rotation therewith. Alternatively, the stud receiving holes in the wheel hub flange can be threaded and receive threaded bolts for securing the brake rotor and/or the vehicle wheel to the flange of the wheel hub for rotation therewith.
The vehicle wheel hub is also provided with a bearing seat for receiving the associated bearing unit. The bearing unit includes an inner race and an outer race. The outer race of the bearing unit includes a generally radially outwardly extending flange having a plurality of circumferentially spaced apart stud receiving holes formed therein. The stud receiving holes of the bearing unit flange receive studs and nuts for securing the outer race to a steering knuckle of a vehicle so as to rotatably support the wheel hub relative thereto.
When used with a preassembled cartridge type of bearing unit, a fully machined wheel hub and a fully machined brake rotor are assembled and installed on a vehicle in the following manner. First, the cartridge bearing unit is installed about the bearing seat of the wheel hub in a press-fit relationship therewith. 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.
Once the bearing unit is installed about the wheel hub, a nut is threaded onto the end of the wheel hub and tightened to pre-load the bearing unit assembly to predetermined specifications. Next, the assembled wheel hub and bearing assembly is secured to the steering knuckle for rotation relative thereto. Following this, a brake rotor of a disc brake assembly and a vehicle wheel are secured to the flange of the wheel hub for rotation therewith. Next, the disc brake assembly, which includes a brake caliper slidably supported on a pair of pins, the pair of brake pads, and a hydraulically actuable piston, is secured via an anchor plate to a fixed part of a vehicle.
When fully assembled on the vehicle, a pair of opposed friction plates of the brake rotor are disposed adjacent the brake pads of the disc brake assembly and separated from engagement therewith by a predetermined normal brake running clearance when the piston is not actuated. During operation, when the piston of the disc brake assembly is actuated, the brake shoes take up the normal running clearance and frictionally engage the friction plates.
In order to provide the normal brake running clearance, the brake rotor needs to be manufactured to tight specifications. In particular, the brake friction plate surfaces need to be oriented in a perpendicular relationship relative to the axis of the rotor, and in a parallel relationship relative to one another. If these tight specifications are not maintained in the friction plate surfaces, excessive lateral or axial runout or excessive thickness variations in the friction plate surfaces of the rotor can occur which can lead to undesirable results. For example, premature or uneven wear of the brake pads can occur which can cause undesirable noise, vibration, or brake shudder.
As discussed above, the brake rotor is secured to the wheel hub. In particular, an inner brake rotor mounting surface of the brake rotor is disposed adjacent an outer brake rotor mounting surface of the wheel hub when the brake rotor is secured to the wheel hub. Typically, the outer brake rotor mounting surface of the wheel hub is machined by a conventional lathe machining process. Thus, when fully assembled on the vehicle, the total “stack up” axial runout of the friction plate surfaces of the brake rotor is the sum of the axial runout of the friction plate surfaces of the brake rotor, the axial runout of the associated outer brake rotor mounting surface of the wheel hub, the axial runout of the associated vehicle wheel hub bearing unit, and any deflection caused by the “clamping” of the associated vehicle wheel.
SUMMARY OF THE INVENTION
This invention relates to an improved vehicle wheel hub and bearing unit assembly and method for producing the same wherein an outer brake rotor mounting surface of the wheel hub and bearing assembly is subjected to a microfinishing machining process. The method for producing the vehicle wheel hub and bearing assembly comprises the steps of: (a) providing a vehicle wheel hub including an inboard end, an outboard end, and a main body having a radially outwardly extending flange, the flange having an outer surface which defines an outer brake rotor mounting surface of the vehicle wheel hub; (b) providing a bearing unit to rotatably support the vehicle wheel hub relative thereto; (c) assembling the bearing unit onto the vehicle wheel hub to produce a vehicle wheel hub and bearing unit assembly which defines a longitudinal axis; (d) preloading the bearing unit; (e) providing a microfinishing assembly having a microfinishing wheel; (f) supporting the vehicle wheel hub and bearing assembly on the microfinishing fixture; and (g) operating the microfinishing fixture whereby the microfinishing wheel engages the outer brake rotor mounting surface of the vehicle wheel hub and bearing unit assembly to produce a finished vehicle wheel hub and bearing assembly, the outer brake rotor mounting surface of the finished vehicle wheel and bearing unit assembly being microfinished relative to the longitudinal axis of the vehicle wheel hub and bearing unit assembly. As a result, the vehicle wheel hub and bearing unit assembly of this invention includes an outer brake rotor mounting surface which is of a near gage quality surface.
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.
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Horne David M.
Santarossa Walter A.
Bellinger Jason R.
Kelsey-Hayes Company
MacMillan Sobanski & Todd LLC
Morano S. Joseph
LandOfFree
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