Abstract:
An improved brake system is provided for a motor vehicle. The system includes a rotor attached to a rim of a wheel and a caliper assembly mounted to a hub of the wheel. The caliper is arranged to retain a friction element and operatively engage the friction element against the rotor.

Description:
CROSS REFERENCE TO RELATED APPLICATION(S)  
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/435,373 filed on Dec. 20, 2002. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to a brake system for a motor vehicle and, more particularly, to a brake system arrangement for a four wheel motorcycle type vehicle.  
         BACKGROUND OF THE INVENTION  
         [0003]    Generally, motorcycles and all terrain vehicles, commonly referred to as ATV&#39;s, typically include two, three and four wheel configurations. In the three and four wheel configurations, adjacent wheels are typically spaced apart to span the width of the vehicle and also share a common axle. Spacing apart the wheels also provides the ability to mount suspension and brake components to a common axle housing or to a wheel hub support structure located on an axle side of the wheel. In addition, conventional motorcycles often utilize a fork arranged where brake componentry can then be attached to the fork.  
           [0004]    However, in a four wheel motorcycle type vehicle of narrow width and including an independent suspension system, a fork style frame arrangement is not available, and the spacing of the wheels may not provide enough space to mount brake components between the wheels. Therefore, typical brake systems with conventional mounting arrangements are not well suited for a four wheel motorcycle of narrow width that does not utilize a conventional fork arrangement for supporting the front wheels.  
           [0005]    Thus, there is a need for a brake system for a narrow width four wheel vehicle that overcomes the aforementioned and other disadvantages.  
         SUMMARY OF THE INVENTION  
         [0006]    Accordingly, an improved brake system is provided for a motor vehicle. In accordance with one aspect of the present invention, the brake system includes a rotor attached to a rim of a wheel and a caliper assembly mounted to a hub of the wheel. The caliper is arranged to retain a friction element and operatively engage the friction element against the rotor.  
           [0007]    In accordance with another aspect of the present invention, the brake system further includes a master brake cylinder mounted to a steering mechanism base plate arranged to rotate with the steering mechanism.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    Other aspects, features, and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiment, the appended claims, and in the accompanying drawings in which:  
         [0009]    [0009]FIG. 1 illustrates a front view of a section of a brake system for a front tire in accordance with the present invention;  
         [0010]    [0010]FIG. 2 illustrates a front view of the section shown in FIG. 1 for both front tires of a four wheel motorcycle type vehicle in accordance with the present invention;  
         [0011]    [0011]FIG. 3 illustrates a top view of an actuation mechanism and a master brake cylinder mounted to a handle bar attachment plate in accordance with the present invention; and  
         [0012]    [0012]FIG. 4 illustrates a top view of FIG. 3 when the handle bar assembly is in a turning condition in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]    Referring now to the drawings, FIG. 1 illustrates an exemplary embodiment of a brake system  10  for a wheel of a four wheel motorcycle type vehicle in accordance with the present invention. Brake system  10  includes a central knuckle and hub assembly  20  which includes a front wheel spindle  30  for supporting a front wheel  40 .  
         [0014]    Front wheel  40  further includes a plurality of rotor clips  50  for attaching rotor  60  to wheel  40  at a radial outboard edge of rotor  60 . Front wheel  40  also supports tire  70  in a convention manner as is known in the art.  
         [0015]    Hub assembly  20  further includes a mounting bracket  80  extending substantially vertically from hub assembly  20  for mounting and supporting brake calipers  90 . Brake calipers  90  house friction elements  100  which operatively engage rotor  60  via hydraulic pressure from brake fluid lines  110 .  
         [0016]    [0016]FIG. 2 shows the brake system  10  of FIG. 1 for both front tires of an exemplary embodiment of a four wheel motorcycle type vehicle in accordance with the present invention. It should be appreciated that the close proximity of the wheels to each other precludes packaging of a brake system on an inside (axle side) of each front tire. In addition, a conventional type fork arrangement with a solid axle between the forks would not provide for the capability of an independent front suspension system. Therefore, the brake system configuration in accordance with the present invention provides a hub mounted caliper that is arranged to engage a rotor attached to a radially outboard edge of the wheel. Such an arrangement provides design flexibility so that the calipers and rotor can be located solely on an outward face of the wheel.  
         [0017]    Referring now to FIGS. 3 and 4, a brake master cylinder arrangement and actuation mechanism  200  is shown in accordance with the present invention. The arrangement includes a brake lever  205  pivotably connected to handle bar assembly  210  and operably coupled through mechanical linkage assembly  220  to master brake cylinder assembly  230 . Mechanical linkage assembly  220  includes a linking member  225  pivotably connected to brake lever  205  and bell crank  240 . Bell crank  250  is pivotably connected at one end to bell crank  240  and at the other end to master cylinder piston  260 . Master cylinder  260  is attached to a handle bar mounting plate  270  that is attached to the base of a handle bar shaft  275  that rotates with the handle bar assembly  210  as represented by the arrow in FIG. 4. Mounting the brake master cylinder to the handle bar mounting plate  270  as opposed to conventional mounting on the handle bars, provides for protection of the master cylinder and accompanying fluid lines from the elements as well as for greater design flexibility for the handle bars.  
         [0018]    In operation, brake lever  220  is drawn towards handlebar assembly  210  via driver input. This in turn draws linking member  230  in the direction of arrow A which rotates bell crank  240  in the direction of arrow B. The rotation of bell crank  240  in turn rotates bell crank  250  causing it to act as a lever arm and compress piston  260  into master cylinder assembly  230  in the direction of arrow C and displace a corresponding amount of brake fluid through brake fluid line  110 . The hydraulic pressure of the displaced brake fluid operates to compress friction elements  100  against rotor  80  which is attached to and rotates with wheel  40 .  
         [0019]    Likewise, as also shown in FIGS. 3 and 4, a similar cylinder arrangement  280  can be actuated by lever  285  to operate a hydraulic clutch arrangement (not shown) for shifting of transmission gears during operation of the vehicle.  
         [0020]    The foregoing description constitutes the embodiments devised by the inventors for practicing the invention. It is apparent, however, that the invention is susceptible to modification, variation, and change that will become obvious to those skilled in the art. Inasmuch as the foregoing description is intended to enable one skilled in the pertinent art to practice the invention, it should not be construed to be limited thereby but should be construed to include such aforementioned obvious variations and be limited only by the proper scope or fair meaning of the accompanying claims.