Patent Publication Number: US-2013239743-A1

Title: Flywheel

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a flywheel and, more particularly, to a flywheel including a plurality of rods that can continuously change the momentum of inertia to increase the energy stored by the flywheel. 
     A flywheel with a fixed inertia is generally provided in a mechanical power transmission system to store kinetic energy. Such an approach is traditional and used in blank forming machines of ceramics, spinning wheels, and steam engines during the Industrial Revolution. In modern days, flywheels are used in machine tools, engines, generators, etc. These flywheels are used to provide a uniform speed. The energy stored in the flywheel is not much, and the storage time of is short. 
     The energy stored by a flywheel is in proportion to the mass of the flywheel and in portion to the square of the speed of the flywheel. Thus, the energy stored in the flywheel can be increased if the speed of the flywheel is increased. However, the stress imparted to the flywheel is also increased when the speed is increased. As a result, the speed of the flywheel is limited by the maximum stress bearable by the material of the flywheel. Thus, it is an issue to increase the energy-storing capacity of the flywheel at a fixed speed and a fixed mass. 
     BRIEF SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide a flywheel including a plurality of rods that can continuously change the momentum of inertia to increase the energy stored by the flywheel. 
     A flywheel according to the present invention includes a body having a central shaft. A disc is mounted around the central shaft and rotatable about a rotating axis. The disc includes a first side and a second side opposite to the first side, with an energy-storing section defined in the first side, and with an energy-releasing section defined in the second side. Each of the energy-storing section and the energy-releasing section includes a lower portion below the rotating axis and an upper portion above the rotating axis. A plurality of rods is slideably mounted on the disc. The rods are arranged in a radiant manner and spaced from one another in a circumferential direction about the central shaft. Each of the plurality of rods has an inner end spaced from the central shaft and an outer end having a spacing to the central shaft larger than the inner end. Each of the plurality of rods slides toward the central shaft under action of gravitational force while the rod is moving through the upper portion of the energy-storing section. Each of the plurality of rods slides away from the central shaft under action of the gravitational force while the rod is moving through the lower portion of the energy-releasing section. A plurality of weights is respectively mounted to the outer ends of plurality of the plurality of rods. 
     Preferably, the disc includes a plurality of hollow cylinders arranged in a radiant manner. The inner end of each of the plurality of rods is slideably received in one of the plurality of hollow cylinders. The outer end of each of the plurality of rods is located outside of the plurality of hollow cylinders. 
     Preferably, each of the plurality of rods has a longitudinal axis not intersecting with the rotating axis. 
     Preferably, a guiding track is mounted in the energy-storing section of the disc. The guiding track includes a lower end below the rotating axis and a critical contact point located between the upper and lower portions of the energy-storing section. The guiding track includes increasing spacings to an outer periphery of the disc from the lower end of the guiding track toward the critical contact point of the guiding track. Each of the plurality of weights contacts with and is compressed by the guiding track while moving from the lower end to the critical contact point. Each of the plurality of rods slides toward the central shaft under action of the gravitational force after the rod has moved upward and passed through the critical contact point. 
     Preferably, a ball is rotatably mounted to each of the plurality of weights. The ball of each of the plurality of weights rolls on the guiding track when the weight is moving from the lower end to the critical contact point of the guiding track. 
     The present invention will become clearer in light of the following detailed description of illustrative embodiments of this invention described in connection with the drawings. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a diagrammatic side view of a flywheel according to the present invention. 
         FIG. 2  shows a partial, cross sectional view of the flywheel of  FIG. 1 . 
         FIG. 3  shows a partial, cross sectional view of the flywheel of  FIG. 1 , illustrating outward movement of rods of the flywheel. 
         FIG. 4  shows a partial, cross sectional view of the flywheel of  FIG. 1 , illustrating inward movement of the rods of the flywheel. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1-4  show an example of a flywheel according to the present invention. In the form shown, the flywheel includes a body  1 , a plurality of rods  2 , a plurality of weights  3 , a guiding track  4 , and a plurality of hollow cylinders  5 . 
     The body  1  includes a central shaft  11 . A disc  12  is mounted around the central shaft  11  and rotatable about a rotating axis together with the central shaft  11 . The disc  12  includes a first side and a second side opposite to the first side. An energy-storing section A defined in the first side, and an energy-releasing section B is defined in the second side. Each of the energy-storing section A and the energy-releasing section B includes a lower portion below the rotating axis and an upper portion above the rotating axis. 
     Each rod  2  is slideably mounted on the disc  12 . The rods  2  are arranged in a radiant manner and spaced from one another in a circumferential direction about the central shaft  11 . Each rod  2  has an inner end  21  spaced from the central shaft  11  and an outer end  22  having a spacing to the central shaft  11  larger than the inner end  21 . In the form shown, the outer end  22  of each rod  2  includes a stud  24 . Each rod  2  has a longitudinal axis not intersecting with the rotating axis. 
     In the form shown, each weight  3  includes a connecting portion  31  in the form of a screw hole threadedly engaged with the stud  24  of the outer end  22  of one of the rods  2 . Furthermore, a ball  33  is rotatably received in a recessed portion  32  of each weight  3  opposite to the connecting portion  31 . 
     The guiding track  4  is located in the energy-storing section A of the disc  12 . The guiding track  4  includes a lower end  46  below the rotating axis and a critical contact point between the upper and lower portions of the energy-storing section A. The guiding track  4  includes increasing spacings to an outer periphery of the disc  2  from the lower end  46  toward the critical contact point. The guiding track  4  further includes a surface  41  facing the disc  2  to guide and support the weights  3  and the balls  33 . 
     The hollow cylinders  5  are mounted on a side of the disc  2  and arranged in a radiant manner. Bolts or the like are extended through fixing portions  54  of each hollow cylinder  5  into the disc  2 . The inner end  21  of each rod  2  is slideably received in one of the hollow cylinders  5 . The hollow cylinders  5  and the rods  2  are provided with guiding rings  23  and  53  to reduce friction. Each hollow cylinder  5  further includes an end cap  52  to retain the guiding ring  53 . The outer end  22  of each rod  2  and the corresponding weight  3  are located outside of the corresponding hollow cylinder  5 , allowing easy assembly and detachment. 
     When the disc  12  rotates about the rotating axis in a direction indicated by arrow C, the rods  2  slide toward or away from the disc  12  according to the angular positions of the rods  2 . Specifically, when a rod  2  is moving from the lower end  46  to the critical contact point of the guiding track  4 , the corresponding weight  3  contacts with and is compressed by the surface  41  of the guiding track  4 . Thus, the rod  2  is moved into the hollow cylinder  5  except the outer end  22 . The moment of inertia of the rod  2  and the weight  3  is decreased. The ball  33  provides smooth sliding movement for the weight  3 . 
     When a rod  2  is moving through the upper portion of the energy-storing section B above the critical contact point of the guiding track  4 , the rod  2  slides toward the central shaft  11  under action of gravitational force. 
     When a rod  2  is moving through the lower portion of the energy-releasing section B, with the rod  2  slides away from the central shaft  11  under action of the gravitational force as well as centrifugal force acting on the rod  2  and the corresponding weight  3 . Thus, the rod  2  extends out of the corresponding cylinder  5  and partially outside of the disc  2 . The moment of inertia of the rod  2  and the weight  3  is increased, leading to an increase in the energy of the flywheel while cooperating with the centrifugal force. The momentum of inertia of each weight  3  is decreased again when the weight  3  is moving through the energy-storing section A. Thus, by continuously changing the momentum of inertia of each weight  3 , the energy stored by the flywheel can be increased. The power of the flywheel can be transmitted through the central shaft  11  or other conventional transmission devices. The flywheel is suitable for driving a generator to produce electricity. 
     Although specific embodiments have been illustrated and described, numerous modifications and variations are still possible without departing from the essence of the invention. The scope of the invention is limited by the accompanying claims.