Patent Publication Number: US-2011052113-A1

Title: Balancer for a rotating object

Description:
FIELD 
     A balancer for balancing and stabilizing a rotating object 
     BACKGROUND 
     U.S. Pat. No. 3,733,923 (Goodrich et al.) entitled “Economical Automatic Balancer for Rotating Masses” and U.S. Pat. No. 5,142,936 (McGale) entitled “Apparatus for dynamical balancing of rotating objects and method for making same” describe balancers that are made from a bent metallic tube, and filled with spherical counterweights and damping fluid. Other known balancing devices use mercury as the counter weight. 
     SUMMARY 
     There is provided a balancer for a rotating object comprising a rigid body having a first portion and a second portion. The first portion defines a lower section of a circular raceway and the second portion defines an upper section of the circular raceway. A balancing medium is positioned within the circular raceway. A connector connects the first portion and the second portion to form the circular raceway. 
     According to another aspect, there is provided a method of forming a balancer for a rotating object, comprising the steps of 
     forming a first portion of a rigid body to form a lower section of a circular raceway, the lower section having a volume sufficient to contain a balancing medium, the first portion having a first threaded surface; 
     forming a second portion of a rigid body to form an upper section of the circular raceway, the upper section having a second threaded surface for engaging the first threaded surface; 
     filling the lower section with a balancing medium; and 
     attaching the first portion and the second portion by threading the threaded recessed cavity onto the threaded upstanding flange to form the circular raceway. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to be in any way limiting, wherein: 
         FIG. 1  is a side elevation view in section of a dynamically balancing apparatus. 
         FIG. 2  is an exploded side elevation view in section of a dynamically balancing apparatus. 
         FIG. 3  is a top plan view of the first portion of the dynamically balancing apparatus. 
         FIG. 4  is a top plan view of the second portion of the dynamically balancing apparatus. 
         FIG. 5  is an exploded side elevation view in section of an alternative dynamically balancing apparatus. 
     
    
    
     DETAILED DESCRIPTION 
     A balancer for a rotating object, generally identified by reference numeral  10  will now be described with reference to  FIG. 1 through 4 . An alternative embodiment will then be described with reference to  FIG. 5 . 
     Structure and Relationship of Parts: 
     Referring to  FIG. 1 , balancer  10  is made from a rigid body  12  having a first portion  14  and a second portion  16 . Referring to  FIGS. 3 and 4 , first portion  14  and second portion  16  of rigid body  12  are preferably annular in shape. The cross-section of rigid body  12  need not be circular, and may be square or rectangular, as shown in  FIG. 1 . The shape of rigid body  12  must be able to accommodate a circular raceway  20 , and to allow for a balanced load when rotating. Referring to  FIG. 2 , first portion  14  defines a lower section  18  of circular raceway  20  and second portion  16  defines an upper section  22  of circular raceway  20 . It will be understood that “upper” and “lower” refer to the orientation during a preferred mode of assembly. Once assembled, balancer  10  may take any orientation, depending on the intended purpose and the object to be balanced. The cross-section of circular raceway  20  may be circular, as shown in  FIG. 5  or non-circular, as shown in  FIG. 1 . As shown in  FIG. 1 , upper section  22  is a cover for lower section  18 , which has a rounded bottom surface, and flat sides that rise to the approximate height of the balancing medium  24  that will be placed in circular raceway  20 , as will be described below. In the embodiment depicted in  FIG. 2 , first portion  14  has an annular upstanding section  30  with lower section  18  of circular raceway  20  being recessed into upstanding section  30  such that, when assembled, circular raceway  20  is approximately in the center of rigid body  12 . Upstanding section  30  engages a recess  32  in second portion  16 , which acts as the cover for lower section  18 . Upstanding section  30  has seals  36  that are pressed against recess  32  to seal circular raceway  20  when assembled. 
     As depicted, the volume of circular raceway  20  is contained entirely in lower section  18 , with upper section  22  providing a cover to enclose circular raceway  20 . However, it will be understood that second portion  16  may be formed such that upper section  22  also contains some of the volume of circular raceway  20 . An example of this can be found in  FIG. 5 , which will be described in more detail below. For ease of assembly, the volume of lower section  18  is sufficiently large to contain the entire balancing medium  24 , which in most situations is between 40% and 80%, and preferably between 65% and 75% of the volume of circular raceway  20 . Balancing medium  24  may be any convenient medium that is able to move in circular raceway  20 . In one example, balancing medium  24  is made up of spheres in a liquid that acts as a fluid dampener for the spheres, such as liquid silicone. In another example, the balancing medium is a fluid, such as mercury or other heavy fluids. 
     First and second portions  14  and  16  are connected by a connector to form circular raceway  20 . In the embodiment depicted in  FIG. 2 , this is done by providing a threaded connection. There is a first threaded surface  26  on first portion  14  that mates with a second threaded surface  28  on second portion  16 . 
     Method of Manufacture: 
     A method of manufacturing a preferred embodiment of balancer  10  will now be described. Referring to  FIG. 3 , first portion  14  of rigid body  12  is formed with lower section  18  of circular raceway  20 . Preferably, lower section  18  is formed in annular upstanding section  30 , such that circular raceway  20  is centered when balancer  10  is assembled. Lower section  18  has first threaded surface  26  and preferably has a volume sufficient to contain the balancing medium. Referring to  FIG. 4 , second portion  16  is formed with upper section  22  of circular raceway  20 . Upper section  22  has second threaded surface  28  in recess  32  for engaging first threaded surface  26  and is designed to cover lower section  18  to enclose circular raceway  20 . First and second portions  14  and  16  may be formed by machining or molding. The material is preferably aluminium, however adequate results may also be obtained using other materials that are sufficiently rigid for the intended application. Referring to  FIG. 2 , lower section  18  is then filled with balancing medium  24 , and first portion  14  and second portion  16  are then attached by engaging upstanding section  30  and recess  32  and threading first and second threaded surfaces  26  and  28  together to enclose circular raceway  20 . Once assembled, first portion  14  and second portion  16  may be welded or otherwise secured to prevent separation. 
     Variations: 
     Referring to  FIG. 5 , an alternative balancer  100  is shown. As with balancer  10 , balancer  100  has first and second portions  14  and  16  that combine to form circular raceway  20 . As shown, circular raceway  20  has a round cross-section. In addition, circular raceway  20  has the volume divided between lower section  18  and upper section  22 . First threaded surface  26  is located on one of the upstanding flanges  40 , which also act to increase the volume of lower section  18 . Second threaded surface  28  is located in one of the recesses  42  that correspond to upstanding flanges  40 . Both flanges  40  and recesses  42  are circular. 
     As depicted, lower section  18  may have a volume that is less than the volume of the balancing medium. However, when spheres are used, the spheres will extend above upstanding flange  40 , such that the effective volume contained is greater that what would otherwise be the case. 
     Advantages: 
     Balancer  10  described above is designed to be used for balancers having raceways that are less than 5 inches in diameter, and preferably around 4 inches. For diameters that small, traditional methods of bending tubing are not practical, as the tight radius of curvature may result in kinks or a narrowed cross-section. By using the above-described apparatus and method, smaller balancers can be made, which can then be used on, for example, the flywheel of an ATV, such as a snowmobile. 
     In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements. 
     The following claims are to be understood to include what is specifically illustrated and described above, what is conceptually equivalent, and what can be obviously substituted. Those skilled in the art will appreciate that various adaptations and modifications of the described embodiments can be configured without departing from the scope of the claims. The illustrated embodiments have been set forth only as examples and should not be taken as limiting the invention. It is to be understood that, within the scope of the following claims, the invention may be practiced other than as specifically illustrated and described.