Abstract:
A disc brake rotor element for a vehicle braking system, the disc brake rotor having a plurality of heat sinks positioned in the surface area contacted by the disc brake shoes in order to aid in the dissipation of heat from the brake rotor, thus maintaining the brake rotor at a cooler temperature which improves the efficacy of the braking system.

Description:
RELATED APPLICATIONS 
       [0001]    Applicant claims the benefit of provisional application Ser. No. 60/998,903, filed Oct. 15, 2007. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to brakes, and in particular, disc brake rotors, which incorporate a plurality of individual heat sinks which improve the cooling of the disc brake rotor and the prevention of overheating. 
         [0004]    2. Description of the Prior Art 
         [0005]    Motor vehicle brakes have become more sophisticated as motor vehicles have developed. This sophistication has been driven by the fact that motor vehicles are increasingly faster than when first introduced, and that safety concerns are a high priority, not only for the manufacturer of the vehicle, but also for the purchaser of the vehicle, either for regular home owner vehicles or racing vehicles. 
         [0006]    Motor vehicle brakes have evolved from the drum brake in which a drum member rotated with the wheel and force was applied to the inner circumference of the drum by arcuate pads which were pneumatically operated via the brake pedal to push outwardly against the arcuate inner surface of the brake drum in order to slow and stop the vehicle. 
         [0007]    The drum brake eventually evolved into a disc brake which had better stopping characteristics than the drum brake and which would become a standard feature on most vehicles with respect to the front brakes, although many vehicles are equipped with four wheel disc brakes. The concept of the disc brake is a circular rotor which rotates on the axle with the wheel, the annular outer contact surface of the rotor passing between a pair of opposing brake shoes which are pneumatically activated to press against the rotating rotor by application of the brake pedal in order to slow or stop the rotor and the vehicle. 
         [0008]    The enemy of all brake mechanisms is heat. The mechanism utilized to slow or stop a vehicle in both the drum brake and the disc brake is friction, and that friction generates elevated temperatures of the brake elements which will affect their performance, particularly when brakes are repeatedly applied. This can occur in a passenger vehicle traversing a downhill curving road, which would require constant reapplication of the brakes to slow down or in racing situations wherein a race car must brake from relatively high speeds in order to traverse a curve or turn and must repeatedly perform this function. 
         [0009]    The heat problem was first addressed with respect to disc brakes by forming the disc brake with the two spaced apart rotors having radial arms positioned there between. In this configuration, a disc brake shoe contacts one of the rotating rotors and the opposing disc brake shoe contacts the spaced apart rotating rotor. The heat generated in slowing or stopping the vehicle remains the same as if both disc brake shoes were contacting the same rotor, but in this design, the heat is divided between two separate rotating rotors. The radial arms sandwich between the disc brake rotors serve to increase surface area to dissipate heat and to generate air flow turbulence which aids in the cooling of the brake mechanism elements. 
         [0010]    The disc brake rotor in most common usage is fabricated from metal, such as steel, metal matrix, ceramic, carbon, carbon fiber, or combinations thereof, due to fabrication costs and availability of material. More exotic racing cars have addressed the heat issue of brakes by looking to alternative materials such as carbon or carbon fiber rotors. These carbon fiber disc rotors perform very well on race cars in that they remain stable at significantly high temperatures and are able to cool rapidly upon release of the brake mechanism. Unfortunately the cost of material and fabrication time make these carbon fiber rotors prohibitive with respect to use on your normal family car. 
         [0011]    There therefore has been a need for a disc brake rotor which was capable of dissipating heat without affecting the performance of the brake mechanism and which could be massed produced without any significant increase in cost. 
       OBJECTS OF THE INVENTION 
       [0012]    An object of the present invention is to provide for a novel disc brake rotor which incorporates a plurality of heat sinks which prevents the overheating of the rotor. 
         [0013]    A still further object of the present invention is to provide for a novel disc brake rotor which incorporates a plurality of heat sinks which allow the rotor to cool faster and which extends the life expectancy of the disc brake rotor. 
         [0014]    A still further object of the present invention is to provide for a novel disc brake rotor which incorporates a plurality of heat sinks, each of the heat sinks maximizing its surface area in order to dissipate heat. 
         [0015]    A still further object of the present invention is to provide for a novel disc brake rotor incorporating a plurality of heat sinks, which heat sinks can be easily positioned in the outer annular portion of the disc brake rotor. 
       SUMMARY OF THE INVENTION 
       [0016]    A disc brake rotor element for a vehicle braking system, the disc brake rotor having a plurality of heat sinks positioned in the surface area contacted by the disc brake shoes in order to aid in the dissipation of heat from the brake rotor, thus maintaining the brake rotor at a cooler temperature which improves the efficacy of the braking system. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    These and other objects of the present invention will become apparent, particularly when taken in light of the following illustrations wherein: 
           [0018]      FIG. 1  is a plan front view of a first embodiment of a disc brake rotor of the present invention; 
           [0019]      FIG. 2  is an exploded end view of a disc brake rotor of the present invention; 
           [0020]      FIG. 3  is an enlarged perspective view of the heat sink element incorporated into the disc brake rotor; 
           [0021]      FIG. 4  is a front plan view of a second embodiment of a disc brake rotor of the present invention; 
           [0022]      FIG. 5  is an exploded view of a disc brake rotor of the present invention; and 
           [0023]      FIG. 6  is a perspective view of a second embodiment of a heat sink for a disc rotor. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]      FIG. 1  is a front plan view of a disc brake rotor  10  of the present invention. The disc brake rotor  10  has a central hub portion  12  for mounting the disc brake rotor and it has an annular surface contact area  14  defined as the annular area between the hub portion  12  and the outer circumferential wall  16  of the rotor  10 . This annular surface contact area  14  spins within a brake shoe  17  (see  FIGS. 4 and 5 ) having a pneumatically actuated contact surface which will frictionally engage the annular surface contact area  14  of spinning disc rotor  10  in order to reduce or completely stop its revolutions. 
         [0025]    In accordance with Applicant&#39;s invention, there would be a plurality of heat sinks  18  embedded in preformed apertures  20  in the annular contact surface area  14 . It will be recognized by one of ordinary skill in the art that these preformed apertures  20  and the attendant heat sinks  18  which are positioned therein and pressed in position, must be positioned in order to balance the rotation of the disc brake rotor  10 . In the instant  FIG. 1 , for purposes of explanation, the disc brake rotor  10  is fitted with 48 heat sinks  18 . It should be noted that there can be more or less of such heat sinks depending upon the size of the rotor  10  and the area of the annular contact surface  14 . The heat sink is illustrated in  FIG. 3  and is tubularly cylindrical in shape having a plurality of inwardly depending fins  22 . Fins  22  are spaced apart from each other and are radially positioned, but do not contact each other or extend to the axis of the tubular cylindrical heat sink. 
         [0026]      FIG. 2  is an end exploded view illustrating the cross section of the heat sink  18  and the heat sink prior to its being positioned within the annular surface contact area  14  of the disc brake rotor  10  and pressed into position. 
         [0027]    In this design, the plurality of heat sinks  18  provide a larger surface area for cooling of the disk brake rotor  10  by the air stream flowing past it. The heat sink material should be a close thermal expansion match to the rotor material in order to expand and contract complimentary with the rotor. Alternatively, the heat sink  18  could be provided with a slit  19  along its outer perimeter and either pressed or brazed into the aperture  20  formed in the rotor  10  (See  FIG. 6 ). 
         [0028]    As an example, a cast iron rotor has a coefficient of thermal expansion of 11.8 ppm/C at 20 degrees C., and a steel heat sink  18  of the type described would have a coefficient of thermal expansion of approximately the same. 
         [0029]    Conversely, a titanium rotor has a coefficient of thermal expansion of 8.6 ppm/C at 20 degrees C. To match a titanium rotor, a metal matrix material may have to be used of the type known as THERMKON 83, a trademark product of CMW, Inc. of Indianapolis, Ind., which has a coefficient of thermal expansion of 8.5 ppm/C at 20 degrees C. 
         [0030]    The heat sink material could be fabricated from metal, metal matrix, ceramic, carbon, carbon fiber, or combinations thereof, depending upon the rotor material, the coefficient of thermal expansion and the necessity of matching the coefficient of thermal expansion. 
         [0031]    In  FIGS. 1 ,  2 , and  3 , the heat sink  18  has been positioned, pressed or brazed into the annular contact surface area  14  of the disc brake rotor  10  such that the axel of the heat sink  18  is parallel to the axel of the rotor. 
         [0032]    In an alternative embodiment as illustrated in  FIGS. 4 and 5 , a heat sink of the same design  18  could be positioned into the circumferential edge  16  of the disc rotor  10  either radially  30  as illustrated in example 1 of  FIG. 4 , or obliquely  32  as illustrated in Example 2 of  FIG. 4 . In each of the instances in  FIG. 4 , the heat sink  18  again serves to provide more surface area in order to dissipate the heat. With respect to the embodiment illustrated in  FIG. 4 , consideration must again be given to the positioning of the heat sinks  18  about the peripheral edge  16  of the disc rotor  10  in order to maintain the balance of the disc rotor and not disrupt its plane of rotation such as to cause wobble and inadvertent contact with the brake shoe. 
         [0033]    While the heat sink  18  is illustrated in  FIGS. 1 ,  2 , and  3 , which is positioned transversely to the annular contact surface area  14  of disc rotor  10 , and therefore is limited in its size by the thickness of the disc rotor, the heat sink  18  is illustrated in  FIGS. 4 and 5  is limited in its diameter by the thickness of the brake rotor  10 , but its length may be greater than that of the heat sink  18  illustrated in  FIGS. 1 ,  2 , and  3  depending upon the width of the annular contact area of the disc rotor. 
         [0034]    Therefore, while the present invention has been disclosed with respect to the preferred embodiments thereof, it will be recognized by those of ordinary skill in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore manifestly intended that the invention be limited only by the claims and the equivalence thereof.