Abstract:
A wheel ballast device including at least two hollow ballast chambers, each of which defines an interior cavity therein. A movable medium is contained within each of the interior cavities and is freely movable within the respective ballast chamber. An attachment device is provided to secure the ballast chambers to the wheel.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates generally to a wheel ballast device for attachment to a wide variety of vehicular wheels, including wheels for commercial carriers, privately owned trucks, sport utility vehicles, passenger cars and airplane landing gear. The wheel ballast is a self-compensating device or apparatus, which dynamically and constantly balances rotating wheels while they are in motion.  
         BACKGROUND OF THE INVENTION  
         [0002]    Dynamic balancing of rotating objects is known in the prior art. Reference is made to the following patents: U.S. Pat. Nos. 3,164,413 to Salathiel, 3,316,021 to Salathiel, 3,346,303 to Wesley, 3,376,075 to Mitchell, 3,733,923 to Goodrich, 3,799,619 to LaBarber, 3,913,980 to Cobb, 3,953,074 to Cox, 4,388,841 to Gamble, 4,674,356 to Kilgore, 5,048,367 to Knowles, 5,142,936 to McGale, 5,253,928 to Patti, 5,503,464 to Collura and 6,128,952 to LeBlanc describe inventions used to dynamically balance rotating objects, usually vehicle wheels.  
           [0003]    U.S. Pat. Nos. 3,164,413 and 3,316,021 to Salathiel describe a hollow annular hoop containing a plurality of spherical weights and a damping fluid. In use, the hoop is attached to a rotating wheel perpendicular to the axis of rotation and concentric to the axis of rotation. The apparatus of the Salathiel patents has the disadvantage of not providing a feasible means of attachment to a vehicular wheel. Furthermore, the Salathiel patents utilize a deformable material for the annular concentricity of the hoop during operation.  
           [0004]    U.S. Pat. No. 3,346,303 to Wesley describes a hollow annular hoop containing a plurality of spherical weights and a measured amount of damping fluid. Wesley provides a hoop with an apex at the outer perimeter so as to reduce the area of contact between the spherical weights and the hoop. The hoop is constructed of a metal formed or welded into the proper shape or configuration. The hoop is attached to the wheel of a vehicle by means of attachment to a mounting fixture, which has several precut lug nut holes adapted to fit a wheel.  
           [0005]    U.S. Pat. No. 3,376,075 to Mitchell describes a dynamic wheel balancer, which has a hollow annular hoop with a plurality of spherical weights and a damping fluid. The hoop is attached to a mounting fixture, which is adapted to fit a variety of wheel and lug nut configurations. The annular hoop is constructed by attaching a U-shaped channel onto a plate in a fluid tight manner.  
           [0006]    U.S. Pat. No. 3,733,923 to Goodrich describes a balancer for rotating masses, which uses an annular hoop, spherical weights, and a damping fluid. The hoop contains a continuous metallic race containing carbon steel balls in a damping fluid. The hoop contains a small section on the interior portion, which is removable for adding the weights and fluid.  
           [0007]    U.S. Pat. No. 3,799,619 to LaBarber describes a vibration dampening assembly, which comprises an annular hoop and spherical weights within the hoop. The outer perimeter of the hoop wall is made up of deformable material so as to assist in retaining the spherical weights in position after they have been distributed by the rotating of the hoop.  
           [0008]    U.S. Pat. No. 3,913,980 to Cobb for a dynamic wheel balancing apparatus discloses an annular hoop with spherical weights, which is placed around a wheel inside a tire of a vehicle. The invention uses non-metallic weights and a damping fluid. The hoop is made of an elastic material, which can deform in use at high rotational speeds.  
           [0009]    The publication Design News described the concept of “Self-Compensating Balancing in Rotating Mechanisms”, in an article dated Apr. 28, 1965. Four requirements for successful application of the method for self-compensating balancing are described. First, there must be inertial forces on the rotating system that cause the mass center to misalign with the rotation center of the support bearings. Second, the rotating system must operate far away from its critical or resonant speed. Third, the bearing must have resiliency. Fourth, the rotor must be sufficiently balanced to avoid damage to itself as it passes through its critical speed during start-up.  
           [0010]    The prior art does not provide a practical and effective device or apparatus for realizing the benefits of dynamical balancing for many possible applications, including vehicular wheel balancing. The prior art fails to provide a design with the durability, ease of installation, and broad compatibility with a range of vehicle wheels that is provided by the wheel ballast. Additionally, the prior art fails to provide a design with a product cost commensurate with the economic benefits provided by dynamical wheel balancing.  
         SUMMARY OF THE INVENTION  
         [0011]    The invention relates to a wheel ballast device having at least two hollow ballast chambers, each defining an interior cavity or compartment. The interior cavities of the respective ballast chambers do not communicate with one another. A movable mass or medium is contained within each of the interior cavities and is freely movable within the respective ballast chamber. An attachment device is provided to secure the ballast chambers to the wheel. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    The features and benefits of this invention will be understood by reference to the following detailed description, as well as by reference to the following drawings, in which:  
         [0013]    [0013]FIG. 1 is a partial cross-sectional view of a wheel incorporating the wheel ballast device of the present invention;  
         [0014]    [0014]FIG. 2 is a fragmentary, enlarged cross-sectional view of the wheel of FIG. 1 taken generally along the lines  2 - 2  in FIG. 1;  
         [0015]    [0015]FIG. 3 is a side view of the wheel of FIG. 1;  
         [0016]    [0016]FIG. 4 is an enlarged cross-sectional view of a ballast chamber taken generally along the lines  4 - 4  in FIG. 3; and  
         [0017]    [0017]FIG. 5 is a partial vertical cross-sectional view of a ballast chamber. 
     
    
     DETAILED DESCRIPTION  
       [0018]    The wheel ballast device  10  disclosed herein makes use of a novel design, which utilizes a multi-segment, annular construction  11 , which is attached to a vehicle wheel  12  by means of a continuous constricting cable, band or strap  13  as shown in FIGS.  1 - 3 . The device  10  is attached inside of an interior longitudinal groove-way  14  of the wheel  12  and contains a movable mass  16  (FIG. 5) that disperses and re-distributes in reaction to centrifugal and inertial forces acting on the wheel  12  and a tire  17  mounted thereon so as to provide a means for active counterbalancing of the vehicular wheel  12  as it rotates about an axis of rotation  18 . The wheel  12  has an outer, tire-holding rim member  19 , defined by a generally flat inner portion  21  from which a pair of opposed rims or flanges  22  project upwardly on opposite sides thereof. The upper edges of the rims  22  engage the inner periphery of the tire. The outer rim  19  thus defines therein the groove-way  14  which is generally trough-shaped and faces the interior of the tire  17 .  
         [0019]    The wheel ballast  10  in its preferred embodiment includes three annular, semi-circular, molded ballast chambers  23  each containing the movable mass  16 , best illustrated in FIG. 3. Each ballast chamber  23  is elongate and defines a narrow interior cavity or compartment  24  having a transverse cross section which in the illustrated embodiment has a generally frusto-conical shape, as illustrated in FIG. 4. The ballast chambers  23  are molded from a compliant material such as a thermoplastic elastomer so as to conform to the shape of the interior of the internal, longitudinal groove-way  14  when affixed to the wheel  12 . Each ballast chamber  23  is defined by two spaced apart end walls  26  and  27  and two contoured angularly oriented side walls  28  and  29 . The end walls  26  and  27  are oriented transversely relative to the side walls  28  and  29 . Top and bottom walls  31  and  32  are generally parallel to one another and extend between and interconnect the respective side walls  28  and  29 . The various walls  26 ,  27 ,  28 ,  29 ,  31  and  32  of each ballast chamber  23  enclose interior cavity  24 . The top wall  31  includes an inwardly projecting channel  33  which extends longitudinally along the top wall  31  near a center thereof. When the wheel ballast  10  is configured as illustrated, each ballast chamber  23  is sized to extend approximately 120 degrees about the axis of rotation  18  of the wheel  12 . In the illustrated embodiment, the channel  33  is defined by the top wall  31  and projects inwardly into the interior cavity  24 .  
         [0020]    Each ballast chamber  23  is attached to a rigid conduit or plate-like member  34  and affixed to the vehicle wheel  12  by means of the constricting cable  13 . Each member  34  is shaped as a thin rectangular strip which has a length approximately equal to that of the corresponding ballast chamber  23 . Extending longitudinally generally along the center of each member  34  is an inwardly projecting rib which defines an outwardly opening channel  36 . Each ballast chamber  23  is attached to the respective member  34  by mechanical means such as adhesion or heat staking, with the rib of member  34  projecting into the channel  33  of the top wall  31 , as discussed further below. Each member  34  holds the respective movable mass  16  and compliant ballast chamber  23  concentric to the spinning wheel  12  during use and provides a structure for attachment to the constricting cable  13 . More specifically, the cable  13  is seated within the outwardly opening channels  36  of the respective members  34  and extends about the periphery thereof.  
         [0021]    In the preferred configuration, the wheel ballast device  10  in its assembled state contains three ballast chambers  23 , three rigid members  34  and a single constricting cable or band  13 . The interior cavity  24  of each ballast chamber  23  is partially filled with the movable mass material  16 , such as sand. The movable mass could also be a suitable damping fluid, such as oil or liquid mercury. It will be appreciated that any suitable method for partially filling the ballast chambers  23  with the movable mass  16  may be utilized. For instance, the ballast chambers  23  can be molded so that one or both ends is open. A first end cap can be attached to one end of the respective ballast chamber  23  to form the end wall  26 . The sand  16  or other movable mass can then be added to the ballast chamber  23 . A second end cap can then be attached to the other end of the respective ballast chamber  23  to form the end wall  27 . In this regard, particular attention should be paid to ensure that the ends of the ballast chamber  23  remain sealed during operating so the movable mass  16  contained therein does not escape the interior cavity  24 . While this is one method of filling and assembling the ballast chambers  23 , it should be appreciated that any suitable method could be used.  
         [0022]    Once the ballast chambers  23  are filled and assembled, a plate-like member  34  is positioned atop each ballast chamber  23  so the rib of member  34  which defines channel  36  is received in the associated channel  33  of the top wall  31 . The members  34  are then affixed to the respective ballast chambers  23 , such as by one of the mechanical means set forth above. The ballast chambers  23  are now ready for installation on the wheel  12 .  
         [0023]    The ballast chambers  23  are attached to the wheel  12  after the air valve of the wheel is in place. Installation is performed by placing the ballast chambers  23  in the groove-way  14  of the wheel  12  and wrapping the cable  13  around the ballast chambers so that it extends within the channel  36  of each member  34 . The cable  13  is then constricted, such as with the use of a tightening tool and an off-the-shelf cable attachment component to secure the free ends of the cable  13  to one another. After installation, the constricting cable  13  is held in constant tension by the pressure provided by the pressurized wheel ballast chambers  23  that conform to the shape of the internal longitudinal groove-way  14  of the wheel  12  as the constricting cable  13  is tightened. Clearance for tire installation is provided as the wheel ballast device  10  is located inside of the recessed groove-way  14  of the wheel  12  and inside the tire  17 , once same is installed on wheel  12 , as shown in FIG. 1, and thus does not interfere with tire placement about the wheel  12 .  
         [0024]    Because the wheel ballast device  10  is comprised of multiple, semi-circular, annular segments, the device does not exhibit the adverse transient behavior that previously known automatic wheel balance devices have shown. That is, during vehicle acceleration and deceleration, the wheel ballast device  10  of the present invention is able to produce the desired counter-balancing effect much more rapidly than previously known wheel balancing products.  
         [0025]    Because the present wheel ballast device  10  is attached around the innermost annular recess of a vehicular wheel, an inherent benefit that the wheel ballast device  10  provides is compatibility with a broad range of vehicles within a standard tire size. That is, within each vehicle category (i.e. commercial trucks having 20″, 19″, . . . 13″ wheels), a standard wheel ballast device according to this invention can be produced to be compatible with all vehicles regardless of vehicle make or model year. The positive network externality afforded by the present design provides it with a strong competitive advantage over competitors.  
         [0026]    The wheel ballast device  10  maintains a wheel/tire in dynamic balance throughout the lifetime of the wheel, which may include several sets of tires. The wheel ballast device  10  minimizes the net shaking force produced by each wheel/tire by actively counterbalancing the imbalances of the tire to provide a smoother, more fuel efficient ride, which also extends the life of tires, suspension components, and steering components by reducing vibration. The wheel ballast device  10  not only provides increased passenger comfort, but also provides improved handling and safety, since wheel imbalance lengthens braking distances and adversely affects cornering ability, particularly in wet conditions. Commercialization and widespread use of the wheel ballast device  10  will have a dramatic impact on the environment through improved fuel efficiency and reduced rate of consumption of vehicle tires.  
         [0027]    It should be appreciated that the foregoing description is for the purposes of illustration only, and alternative embodiments of this invention are possible without departing from the scope of the invention. For instance, while the wheel ballast device has been illustrated herein including a number of rigid conduits equal to the number of ballast chambers, a single conduit could be substituted. In this configuration, the single conduit could wrap around all of the ballast chambers and be tightly secured in place by a suitable locking means. In addition, the attachment device used in the wheel ballast device could be any suitable means other than the constricting cable which secures the ballast chambers together and snug against the wheel. Further, while three ballast chambers have been illustrated, the wheel ballast device of the present invention could include any suitable number of separate chambers.  
         [0028]    Although particular preferred embodiments of the present invention have been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications lie within the scope of the present invention and do not depart from the spirit of the invention, as set forth in the foregoing description and drawings, and in the following claims.