Process of manufacturing a corner assembly

A process for manufacturing and assembling a corner assembly for a vehicle to achieve a perpendicular relationship between an axle of a vehicle and first and second braking surfaces on a rotor. In this process, after an inner race of a bearing is pressed onto a wheel hub and an outer race is pressed into a support structure to define a sub-assembly. The sub-assembly is placed onto a locating fixture such that the outer race supports the sub-assembly in a desired alignment where an out board surface on a radial flange is in a perpendicular relationship with the axis of the wheel hub. An arbor is inserted into an axle bore surrounding the axis of the wheel hub and the sub-assembly is rotated on the inner race to simulate operational condition of a vehicle as the surface of the out-board flange is finished machined to define a perpendicular relationship with the axis of the wheel hub. Once the out board surface is finish machined, the wheel hub is in a condition to receive a rotor by bringing an alignment surface on the rotor into engagement with the finished surface of the wheel hub. The rotor is retained on the hub through studs that extend from the wheel hub for attaching a wheel to the wheel rotor. The wheel hub is located such that radial braking surfaces on the rotor are in perpendicular planes with respect to the axis of the axle and parallel to the surfaces of the friction pads.

This invention relates to a process of manufacturing a corner assembly for a vehicle wherein engagement of an alignment surface on a rotor with a radial flange on a wheel hub maintains the rotor in a relationship with the axis of the wheel hub.

BACKGROUND OF THE INVENTION

In currently manufactured vehicles, it is common to have disc brakes installed on all four corners of the vehicle with the wheels mounted on a hub attached to an axle. The wheel is mounted on a hub that is retained in a bearing that is fixed to a support member that in turn is secured to the suspension of the vehicle. A rotor located on the hub has a peripheral surface that is aligned between first and second friction members retained by a caliper member. A brake application is effected by moving first and second friction members into engagement with first and second braking surfaces adjacent to the peripheral surface of the rotor. In disc brake systems, it is important that the first and second friction members and the rotor are maintained in a parallel relationship, otherwise during a revolution of rotation of the rotor, the axial movement, commonly referred to as “lateral runout”, between the first and second friction members can vary and adversely effect a smooth brake application. The effect of lateral runout is sensed by an operator as a surging action or movement on the brake pedal and/or vibrations in the vehicle.

Various processes have been suggested to define a perpendicular relationship between a brake rotor and the axis of rotation of the wheel hub such as the conjugate machining of a rotor and a wheel hub in U.S. Pat. No. 5,842,388; the finishing of a wheel hub that is attached to a knuckle assembly of a steering mechanism in U.S. Pat. No. 6,212,981; and finishing a rotor when installed on a vehicle in U.S. Pat. No. 6,477,928. The processes disclosed in U.S. Pat. Nos. 5,842,388 and 6,212,981 function in an adequate manner for original equipment that is installed in the manufacture of a new vehicle, unfortunately wear conditions may make it necessary to replace the rotor. Thereafter, when an original rotor is replaced with a new rotor it is possible that manufacturing tolerances may be cumulative and as a result in a stack up of tolerances the resulting “lateral runout” may be unacceptable in a mixture of new and old components in a disc brake. In addition, the process disclosed in U.S. Pat. No. 6,477,928 while functioning in an adequate manner may be too time consuming and costly for wide spread acceptance of by most owners of vehicle.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a process of manufacturing a corner assembly for a vehicle to minimize lateral run out between first and second friction members and a rotor wherein an alignment surface on the rotor engages a surface on a radial flange of a wheel hub to establish a perpendicular relationship with the axis of the wheel hub.

According to this process, a wheel hub is obtained from a source, wherein the wheel hub has a cylindrical body having a first end and a second end with an axial bore that extends from the first end to the second end. The wheel hub is further defined by a peripheral surface with a radially extending flange that is located between the first end and the second end, a wheel pilot adjacent the first end, and a rotor pilot between the wheel pilot and an out-board side of the flange, a plurality of bolts that extend from an in-board side of the flange toward the out-board side of said flange, and a journal section that extends from the second end toward the radial flange. Thereafter, a bearing defined by an inner race and an outer race with a plurality of rollers located there between is obtained from a source and the inner race is pressed onto a journal section of the cylindrical body of the wheel hub to secure the bearing to the wheel hub. Then the outer race is pressed into an axial opening in a support structure until a lip on the outer race engages a first end of the support structure and a groove on the outer race adjacent the second end extends past a second end of the support structure. A ring is inserted into the groove in said outer race to maintain a fixed relationship between the groove and the second end of the support structure to define a sub-assembly of the corner assembly. This sub-assembly is located in an arbor such that the second end of the outer race and the out-board side of the radial flange on the wheel hub are located in a horizontal plane. A first vertical force is applied to the support member to hold and retain the radial flange on the wheel hub in the horizontal plane and the outer race in a stationary position with respect to the support member. A tool is inserted into the axial bore of the wheel hub and the wheel hub is rotated on the inner race to finish machine the out-board side of the radial flange and thereby define a perpendicular relationship between the out-board side of the flange and the axis of the wheel hub under operational conditions that may be experienced when installed on a vehicle. The sub-assembly is now ready for installation of a rotor by positioning an alignment surface on the rotor in contact with the finished out-board side of the flange such that the first and second opposing friction surfaces are in planes that are perpendicular to the axis of the wheel hub. A wheel is placed on the wheel hub and after nuts are screwed onto a plurality of bolts that extend from the wheel hub, the alignment surface on the rotor is held tight against the finished surface on the out-board surface on the radial flange to maintain the first and second opposing friction surfaces in the perpendicular relationship with the axis of the wheel hub to define a corner assembly.

An advantage of this invention resides in a process of manufacturing a wheel hub for a corner assembly wherein a surface on a radial flange is finish machined to define a perpendicular relationship with the axis of rotation of a bearing that is secured to the wheel hub and this finished surface is mated with an aligning surface on a rotor such that a desired lateral runout is achieved when the corner assembly is installed on a vehicle.

A further advantage of this invention resides in a process of machining and finishing a wheel hub wherein an outer race of a bearing is held stationary while the wheel hub is rotated about the axis of rotation of the bearing to define a perpendicular relationship between the axis of the wheel hub and an out-board surface on a flange to simulate operational conditions that may occur when installed on a vehicle.

DETAILED DESCRIPTION

FIG. 1illustrates a corner assembly10and a disc brake12for a vehicle made according to the present invention. The corner assembly10that includes a bearing14located between a wheel hub16and support structure18to align brake engagement surfaces20and22on a rotor24in parallel planes with respect to corresponding first28and second30friction members or pads retained in a caliper27of the disc brake12.

The manufacture of the corner assembly10begins with a wheel hub16of a type illustrated inFIG. 2that has been designed into a general desired configuration. The wheel hub16being defined by a cylindrical body31having a first end35and a second end36with an axial bore32that extends from the first end35to the second end36, a portion33of which is splined. A mounting flange38that is located between the first end35and the second end36radially extends from peripheral surface40of the cylindrical body31. The cylindrical body31also includes at least the following surfaces: a journal surface42located between the second end36and flange38that receives the bearing14, a rotor pilot surface44that receives rotor24, a wheel pilot surface46that receives a wheel rim48, an inboard surface50on radial flange38and outboard surface52on radial flange38. A plurality of mounting studs54(only one being shown) that are pressed into corresponding openings56that are located in a fixed distance arc around the axis of bore32.

Once the wheel hub16has been obtained from a source a bearing14is pressed on to the journal surface42. It is anticipated that either a ball or tapered bearing would work equally well but for simplicity in this application, a ball bearing14was selected.

Bearing14is defined by: an outer race58with a cylindrical body having a lip60on a first end62, a peripheral groove64located adjacent to a second end66and an inner guide surface68that located between the first end62and the second end66: a two piece inner race70,70′ that defines a cylindrical body having a first end72and a second end74with an inner guide surface76located there between; and a plurality of balls78,78′ are retained between guide surfaces68and76. The length of the inner race70,70′ is less than the outer race58by an amount such that when the inner race70,70′ is pressed onto journal surface42of the wheel hub16to bring the first end72into engagement with shoulder51on the inboard side of flange38and end36of the wheel hub16is rolled into engagement with the second end74, the bearing14is retained on the wheel hub16. The retention of the bearing14on the wheel hub16could also occur through the use of a half shaft and nut.

Once the bearing14is attached to the wheel hub16, a next step is the attachment to a support structure18by pressing the outer race58into an axial opening80in the support structure18until lip60engages a first side82of the support structure18and groove64extends past a second side84of the support structure18. Thereafter, a ring86is located in groove64to maintain a fixed relationship between the groove64and the second side84such that the wheel hub16is attached to the support structure18to define a sub-assembly, as illustrated inFIG. 3.

Up to this point the components in the sub-assembly have not been evaluated with respect to tolerance stack up and since it is important that brake engagement surfaces20and22on a rotor24that will be mated with the wheel hub16is positioned in parallel planes with respect to corresponding first28and second30friction pads of disc brake12, the sub-assembly ofFIG. 3is placed on an arbor90as illustrated inFIG. 4.

The sub-assembly is located on a locating fixture94of a press member90such that the second end62of the outer race58of bearing14and the surface52on out-board side of radial flange38on the wheel hub16are located in a horizontal plane. A vertical force F1is applied to the support structure18is opposed by a reaction force F2that acts through the outer race58to hold the outer race58stationary while retaining the radial flange38on the wheel hub16in this horizontal plane. Thereafter, an arbor tool92is inserted into axial bore32and mated with splines33of the wheel hub16to rotate the wheel hub16on the inner race70while finish machining surface52on the out-board side of radial flange38to define a perpendicular relationship between surface52and the axis of axial bore32of the wheel hub16. With the outer race58held stationary and the rotation of wheel hub16only occurring on the inner race70conditions similar to those that would be encountered during vehicle operation are more closely achieved than with some prior processes in establishing such a perpendicular relationship.

Under some circumstances it may be necessary to increase the vertical force F1to a greater level to sandwich the outer race58between support structure18and locating fixture94to hold and maintain the outboard surface52in the horizontal plane during the finish machining by cutter tools96,96. However the intensity of the vertical force F1should be limited to a value that prevents rotation of the outer race58without effecting a tolerance relationship between the outer race58, plurality of balls78,78′ and inner race70,70′ that could effect the rotational friction there between. Once surface52is finish machined to a perpendicular relationship with respect to axial bore32, the wheel hub16is ready to receive a rotor24. If the intensity of the vertical force F1reaches a predetermined level, it may be necessary to include a stop91that extends from the locating fixture94and engages the support structure18to assure that the rotation of the wheel hub16only occurs on the inner race70,70′.

A rotor24is obtained from a source and defined by at least the following characteristics: an alignment surface23that is located adjacent an inner peripheral surface21and first20and second22opposing friction surfaces that are located adjacent an outer peripheral surface25. The rotor24is placed on wheel hub16by placing the inner peripheral surface21on rotor pilot surface44of wheel hub16such that the plurality of bolts or studs54attached to the radial flange38extend through openings19(only one is shown) that surround the inner peripheral surface21of the rotor24to bring the alignment surface23into contact with the finished surface52on the outboard side of radial flange38and at the same time bringing the first20and second22opposing braking surfaces into perpendicular alignment with the axis defined by the axial bore32of the wheel hub16. Once the rotor24has been located on wheel hub16and with the first20and second22opposing braking surfaces aligned with the corresponding first28and second30friction members or pads retained in a caliper32, it may be necessary to install keepers on studs54if the wheels for a vehicle are not going to be attached at this time. We will assume that a wheel would be attached at this time to complete this assembly.

Once a wheel is obtained from a source, a center opening100on the wheel is located on wheel pilot surface46such that the plurality of bolts54extend through corresponding openings102in the wheel. Thereafter, nuts55are screwed onto the plurality of bolts54to bring the alignment surface23on rotor24into full engagement with surface52on the out-board side of radial flange38to maintain the first20and second22opposing friction surfaces in perpendicular alignment with the axis of axial bore32of wheel hub16and the axle of the vehicle to define a corner assembly10wherein the first20and second22opposing friction surfaces on rotor24are located in planes to minimize any lateral run out of the rotor24when in operation in a vehicle.