Abstract:
This invention relates to a method of balancing a rotating mass mounted on a compliant axis. This method uses acceleration vector information, extracted only from points on said mass while in motion, to determine the relocation of movable weights mounted on said mass. The shifting of these weights causes the center of gravity to coincide with the intended center of rotation which, in turn, causes the mass to be dynamically balanced.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     Not Applicable  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not Applicable  
       REFERENCE TO SEQUENCE LISTING  
       [0003]     Not Applicable  
       BACKGROUND OF THE INVENTION  
       [0004]     This invention falls into the general field of balancing rotating members, and the specific field of the dynamic balancing of wheel-and-tire assemblies of moving vehicles in a continuous and instantaneous manner while said vehicle is in use and in motion. This invention may have other applications in other fields. It falls most readily into Current U.S. Classification 301/5.22.  
         [0005]     The continuously self-adjusting dynamic balancing of rotating objects is known in the prior art. U.S. Pat. No. 3,953,074 to Cox, U.S. Pat. Nos. 4,388,841 and 6,267,450 to Gamble, U.S. Pat. No. 4,674,356 to Kilgore, U.S. Pat. No. 4,755,006 to Clay, et al., U.S. Pat. No. 5,048,367 to Knowles, U.S. Pat. No. 5,142,936 to McGale, U.S. Pat. No. 5,460,017 to Taylor, U.S. Pat. No. 5,466,049 to Harmsen, U.S. Pat. No. 5,503,464 to Collura, U.S. Pat. No. 6,719,374 to Johnson, U.S. Pat. No. 4,179,162 to Zarlengo, U.S. Pat. No. 5,073,217 to Fogal, U.S. Pat. Nos. 5,728,243, 5,766,501, and 6,129,797 to Heffeman, and U.S. Pat. No. 6,128,952 to LeBlanc all refer to systems or embodiments which incorporate weights or masses that shift their position along, or within a race or other annular path placed equidistant from the geometric center of a rotating mass. These masses are weights, weights immersed in fluids, fluids only, or some form of media. In each of these examples, these masses are allowed to move about on their own, affected only by the centrifugal forces at play in an unbalanced object.  
         [0006]     Authors of two of these patents, McGale (in U.S. Pat. No. 5,142,936) and Johnson (in U.S. Pat. No. 6,719,374) refer to an Apr. 28, 1965 article published in “Design News” that outlines the four conditions which must occur in order to take advantage of their art. In the second of these four requirements, McGale states “the rotating part must operate above its critical speed”, and, in slightly different words, Johnson cautions “the rotating system must operate far and away from its critical or resonant speed”. It is widely known that in automotive applications the resonant speed of a wheel assembly typically falls between 55 mph and 75 mph. This is the speed at which imbalances are noticed and reported. If the tenets of the Design News article are to be believed, then one must question the usefulness of an art whose design prohibits its use at the very speeds at which they are most needed.  
         [0007]     U.S. Pat. No. 4,179,162 to Zarlengo, U.S. Pat. No. 5,073,217 to Fogal, U.S. Pat. Nos. 5,728,243, 5,766,501, and 6,129,797 to Heffernan, and U.S. Pat. No. 6,128,952 to LeBlanc all refer to systems or embodiments in which the balancing medium or mass is placed directly into the tire cavity. These media are typically comprised of glass beads, silica, small metal beads, or some other finely divided solid material. These all claim to provide some balancing effect. One disadvantage of this art is that the media can be displaced under conditions of high lateral or vertical loads. These occur when the wheel locks up on braking or when the tire strikes an object in the road. Another disadvantage of this art is maintenance. The media must be handled, if not outright replaced with every tire change. The proposed invention has no maintenance, and is not affected by adverse loads.  
         [0008]     None of the above named authors volunteer scientific explanations for the means by which the mass or media migrate to their needed positions. Of those that attempt an explanation, Collura (in U.S. Pat. No. 5,503,464) offers: “. . . fluids will substantially instantaneously counteract imbalances . . . ”, LeBlanc (in U.S. Pat. No. 6,128,952) offers: “an opposite force is created . . . ”, and “. . . the motion . . . encourages the . . . material to migrate . . . ”, and Taylor (in U.S. Pat. No. 5,460,017) concedes: “It is difficult to precisely state the principle by which the balls move”. The author of this invention will clearly state, and in great detail, the principle by which this invention works.  
       BRIEF SUMMARY OF THE INVENTION  
       [0009]     It is the object of this invention to dynamically balance rotating objects while in motion, in a method unlike all other previous art, while simultaneously overcoming all of the previous art&#39;s shortcomings.  
         [0010]     This invention is a method, or process. It is the process of using acceleration vectors, taken from various points on a wheel in motion, to govern the positions of movable wheel weights, with the result of providing for a dynamically balanced wheel. This process may be applied to any rotating mass mounted on a compliant axis.  
         [0011]     This invention overcomes all the previous art&#39;s disadvantages in that it will have no limitations due to speed. It is unaffected by how many times a tire is changed. There is no maintenance. Sudden changes in load have no adverse effect on the mechanism of this invention. This invention is based on existing science that affords precise, quantifiable and controlled results. And lastly, the cost of this invention over the life of the vehicle is low. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0012]      FIGS. 1A and 1B  are of geometric models.  
         [0013]      FIG. 2  is of a sensor assembly.  
         [0014]      FIG. 3  is an external view of a self-powered wheel weight.  
         [0015]      FIG. 3A  is the cross-section of FIG. 3  taken across the middle.  
         [0016]      FIG. 3B  is a cross-section of  FIG. 3  taken lengthwise.  
         [0017]      FIG. 4  is a general view of a wheel utilizing the first embodiment.  
         [0018]      FIG. 4A  is a cross-section of  FIG. 4 .  
         [0019]      FIG. 4B  is a cross-section of  FIG. 4A .  
         [0020]      FIGS. 5A and 5B  are of  FIG. 4  in plan view, with geometric model overlay.  
         [0021]      FIG. 6  is an exterior view of a general wheel utilizing the second embodiment.  
         [0022]      FIG. 6A  is a cross-section of  FIG. 6 .  
         [0023]      FIG. 6B  is another cross-section of  FIG. 6 .  
         [0024]      FIG. 7  is a view of balancing cylinder used in second embodiment.  
         [0025]      FIG. 7A  is a cross-section of  FIG. 7 .  
         [0026]      FIG. 7B  is another cross-section of  FIG. 7 .  
         [0027]      FIG. 8  is an exploded view of a third embodiment.  
         [0028]      FIG. 8A  is a cross-section of a  FIG. 8 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0029]     In order to better understand the proposed invention, a knowledge of centripetal force and simple geometry is required. Centripetal force is a force of acceleration. It is also, by definition, the force required to maintain an object in a circular path around a point. This force, or vector, acts perpendicular to the instantaneous path of the object, and directly toward the point.  
         [0030]     Consider now a rotating mass, mounted on a compliant axis. A compliant axis is one that is not rigid in space; it will deform under forces applied to it. For example, a merry-go-round is mounted on a rigid axis, whereas an automotive wheel is mounted on a compliant one.  
         [0031]     Consider now, instead of a rotating mass, a circle represented by a very large group of separate coordinates, or loci, in a circular path around point in paragraph one. All loci on the mass experience a centripetal force vector, with all vectors directed toward the aforementioned point, which from henceforth shall be referred to as the point of rotation.  
         [0032]     Referring now to  FIG. 1A , circle  20  represents aforementioned rotating mass, or wheel, in dynamic balance. Weights  28   a  and  28   b  are movable weights, whose current positions place the wheel in the balanced condition. Crosshairs  21  represent the point of rotation, circle  22  represents the physical center of the wheel, and symbol  23  represents the center of gravity. Points  24  through  27  are sample loci. Lines  24   a  through  27   a  represent the vector of each locus  24  through  27 , respectively. Lines  24   b  through  27   b  represent the tangent of each locus, respectively. Note that in this balanced condition all vectors are perpendicular to their respective tangents. Accordingly, center of wheel  22 , center of gravity  23  and point of rotation  21  are collocated.  
         [0033]     Refer now to  FIG. 1B , an exaggerated depiction of an out-of-balance condition. Dotted circle  20   a  represents previous position of normally-balanced circle  20 . Center of gravity (c.g.)  23  has been displaced from center of wheel  22  by the addition of fixed weight  28   c . Since circle  20  is mounted on a compliant axis, the offset c.g.  23  pulls center of wheel  22  away from center of rotation  21 . Note that weight  28   c , c.g.  23 , center of wheel  22 , and center of rotation  21  all lie on line of stasis  21   a , which bisects circle  20  at loci  29  and  32 . Observe now loci  29  through  34 , with respective vectors  29   a  through  34   a  and tangents  29   b  through  34   b . Loci  29  and  32  lie on stasis line  21   a . Vectors  29   a  and  32   a  also lie on stasis line  21   a , and are therefore perpendicular to their respective tangents.  
         [0034]     All other possible loci on circle  20 , including  30 ,  31 ,  33  and  34 , produce non-perpendicular vectors. It is no coincidence that these vectors always face toward center of rotation  21 , and away from c.g.  43 .  
         [0035]     Now, in order to return any rotating mass to a balanced state, weight must be added, subtracted, or rearranged. In the case of this invention, only rearrangement is considered. Weights  28   a  and  28   b  are the weights considered for this task, and it must now be determined which direction to move them, either clockwise or counterclockwise. Since the center of gravity of any whole mass shifts in the same direction as any moving part of the mass, and it is desired to shift c.g.  23  toward center of rotation  21 , then weight  28   a  must shift clockwise, and  28   b  counter-clockwise. It is not a coincidence that this is also the orientation of all vectors on either side of stasis line  21   a . Based on this fact—that the acceleration vectors will always point in the direction of balance correction—all that is needed to balance rotating masses on compliant axes are 1) methods of measuring acceleration vectors, and 2) methods of driving self-powered wheel-balancing weights using this vector information.  
         [0036]     Measuring vectors of acceleration is a common process. From the simplest carpenter&#39;s level, to tools incorporating lasers, the means to measure vectors of acceleration, the most commonly referenced of which is earth&#39;s gravity, are all around us. For ease of comprehension a simple pendulum is used in the following illustrated embodiments. The process of directing self-powered weights is also relatively simple and common, and can be performed by a small computer, a small electric motor, and a small power supply.  
         [0037]     It is hereby stressed that although only one device for measuring vectors of acceleration is named below, any device that measures acceleration can and should be considered as being useful in the method of this invention. Similarly, only one means of turning a shaft is named below, but any device of mechanical propulsion should be considered as being useful in the method of this invention.  
         [0038]     Now, turning once again to the drawings,  FIG. 2  shows sensor assembly  40 , a device for measuring acceleration vectors. Beginning with case  42 , to the inside a thin metal strip  44  is securely fastened. Firmly attached to end of strip  44  is pendulum  46 . On one side of pendulum  46  is reflective surface  48 . Directing a beam of light at surface  48  is light  50 , and on either side of light  50  are sensors  52  and  54 . Pendulum  46  is configured so that when it senses an acceleration vector perpendicular to its tangent, it will reflect light substantially back to light  50 , and equally toward sensor  52  and sensor  54 . When the acceleration vector is not perpendicular, pendulum  46  will reflect light more towards either sensor  52  or sensor  54 , depending on the direction of the acceleration vector. Sensors  52  and  54 , and light  50  are connected through wires  56  to computer  58  in  FIG. 3A . Computer  58  is connected to electric motor  60  through wires  56 . Power source  62 , through wires  56 , supplies power to computer  58 , light  50 , sensor  52 , sensor  54 , and motor  60 .  
         [0039]     Electric motor  60  drives gear  66  by means of shaft  64 . Gear  66  engages ring teeth  68  in  FIG. 4B , which are cut into annular track or race  70 . Referring to  FIGS. 4, 4A , and  4 B, annular race  70  is machined into wheel  72 . Computer  58  is programmed to have motor  60  drive weight  100  around race  70  in the same direction as the acceleration vector, as sensed by pendulum  46 . When the acceleration vector is perpendicular, weight  100  does not move.  
         [0040]     Additional explanations of relationships of this embodiment are as follows: Referring to  FIGS. 3, 3A  and  3 B, self-powered balancing weight  100  is comprised of case  102 , with chambers  104  and  106 . Motor  60  resides in chamber  104 . Computer  58 , sensor assembly  40 , and power source  62  reside in chamber  106 . Referring simultaneously to  FIG. 4B , landings  74  rests on the tops  76  of ring teeth  68 , and button  78  engages slot  80 . Button  78  is held under tension by spring  82 . Spring  82  is secured by screw  84 . Holes  86 , equally spaced on race  70 , can be seen in  FIGS. 4, 4A , and  4 B, and provide for drainage.  
         [0041]     A description of the dynamics of this embodiment will now be undertaken. Refer to  FIG. 5A  of wheel  72 , with three identical balancing weights, labeled  100   a ,  100   b , and  100   c . Weights  100   a, b  and  c  are in random positions along race  70 , and wheel  72  is in a balanced state. Since the wheel is balanced, all acceleration vectors are perpendicular to their tangents, and all weights are dormant.  
         [0042]     Refer now to  FIG. 5B , where an imbalance has developed in wheel  72 . The acceleration vector for weight  100   c  has shifted to its right. The same can be said for weight  100   b , though to a much lesser degree. Since weight  100   a  lies on the other side of stasis line  21   a , its acceleration vector has shifted to its left. Since each weight has been configured to follow its respective vector, weight  100   c  will shift counterclockwise,  100   b  will do likewise, but to a lesser degree, and  100   a  will shift clockwise. This process will continue until c.g.  23  and center of rotation  21  once again converge, and wheel  72  has been restored to a balanced condition.  
         [0043]     The second embodiment utilizes the method of moving the weight radially, instead of tangentially, to influence a center of gravity. The changes in vectors of acceleration produced by this method are best detected from a locus not at the weight in question, but from a point that is 45 to 135 degrees relative to the motion produced by such a shift. Since this requires separating the weight and the sensor that governs it, a means of communication between them must be used. In this embodiment, this is accomplished using a small transceiver, incorporated into computer  58 , now referred to as computer  58   a.    
         [0044]     Refer now to  FIG. 6 , a general view of a typical wheel  200  utilizing the second embodiment. Shown in  FIGS. 6A and 6B  is cylindrical cavity  202 , and threaded plug  204 , which seals off cavity  202 , into which cylinder  206  fits.  FIG. 7  is of cylinder  206 , with smaller threaded plug at the top referred to as permanent plug  208 . Referring to  FIG. 7A , just below permanent plug  208  is chamber  210 . Inside chamber  210  is sensor assembly  40 . Through wires  56 , sensor assembly  40 , computer  58   a , and power source  62  are connected to motor  60 . Motor  60  drives threaded shaft  212 . Counterbalance  214  rides on shaft  212 , and is kept from rotating by slots  216 . Shaft  212 , counterbalance  214  and slots  216  are within chamber  218 .  FIG. 7B , a cutaway of chamber  218 , shows more clearly the relationship between counterbalance  214  and slots  216 .  
         [0045]      FIG. 8  illustrates a retro-fit kit of the first embodiment. Kit is comprised of rings  300 , fasteners  302 , and weights  100 . The rings  300  are securely attached to a typical automotive wheel  304  in a concentric manner using fasteners  302 . Weights  100  mount on rings  300  in the same manner as with race  70 , and function in the same manner as in the first embodiment.