Abstract:
A kinetic energy storage device includes first and second counter-rotating variable flywheels coupled to a differential. A control mechanism coupled to both flywheels allows the moment of inertia of each flywheel to be adjusted so that the flywheels, differentia, and control mechanism operate as a true infinitely variable transmission. The differential includes an output to allow kinetic energy to be extracted from and added to the device. The counter-rotating flywheels provide stability and controllability making the device suitable for use with short duty-cycle vehicle motivation. Also disclosed is a vehicle drive train configured to be driven by said kinetic energy storage device and a fixture for providing initial kinetic energy to the device.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based on, and claims priority to, U.S. Provisional Application Ser. No. 61/174,115, filed on Apr. 30, 2009 which is hereby incorporated in its entirety herein by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    1. Field of the Invention 
         [0004]    The claimed invention relates generally to alternative energy devices, and more specifically relates to a kinetic energy storage device having counter-rotating flywheels, a differential, and a control mechanism that operate as a true infinitely variable transmission. 
         [0005]    2. Description of Related Art 
         [0006]    Various methods of storing energy are known in the art. For example, some known methods are hydro-electric, solar/thermal, battery, kinetic energy, and fossil fuel. All of these known methods of energy storage and retrieval involve a cycle. The shortest and most efficient cycle is that of kinetic energy. Kinetic energy can be applied to an object and subsequently retrieved with a very high efficiency. A common kinetic energy storage device uses a flywheel where energy is coupled to a rotating mass by directing torque to the axis of the mass and causing it to rotate. The rotating mass will subsequently continue to rotate, losing energy only to shaft and air frictions of the flywheel. Thus, it is possible to retrieve almost all of the stored kinetic energy from the flywheel, minus any frictional losses. 
         [0007]    Use of a conventional flywheel in vehicle applications has some associated drawbacks. For example a flywheel imparts a gyroscopic effect to the vehicle, affecting the handling, particularly in cresting a hill or turning the vehicle. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    The present invention takes advantage of the efficiency of flywheels and overcomes the shortfalls of conventional vehicle flywheel designs by providing two counter-rotating flywheels coupled to a differential. The common input-output of the differential is coupled, by conventional means such as a drive belt, drive shaft, or the like which in turn can be used to transfer energy to or from a powered device, such as a vehicle drive train. The counter-rotating flywheels are variable inertia, adjustable via a control mechanism to vary the angular velocity of the flywheel with no loss of momentum. This allows variations in their angular velocity resulting in a transfer of momentum to the output of the differential. The combination of the flywheels, differential, and control mechanism acts as a true infinitely variable transmission. The kinetic energy storage device can thus be coupled to, for example, a vehicle drive train and controlled to accelerate or decelerate the vehicle with the loss of kinetic energy of the vehicle subject only to the losses of the drive train friction. As compared to single flywheel device, the counter-rotating flywheels of the present invention provide a more balanced system minimizing the gyroscopic effect imparted to a vehicle by a single flywheel system. And, because the system operates as a true infinitely variable transmission, there is no engagement/disengagement of the differential, allowing a more efficient transfer of power than conventional systems as well as smoother operation. 
         [0009]    A kinetic energy storage device in accordance with a first exemplary embodiment of the present invention comprises first and second counter-rotating flywheels arranged on a common axis, each coupled to an epicyclic differential that allows kinetic energy to be transferred to and from the flywheels. A control rod extends though each flywheel and differential, connected at opposite ends to a control mechanism in each flywheel so that movement of the control rod varies the moment of inertia of both flywheels simultaneously. A control motor coupled to the control rod commands output by rotating the control rod. A threaded screw portion of the control rod extends through a mating threaded nut in the differential which rotates to move the control rod when the difference in angular velocities between the flywheels is not zero. The control mechanism thus acts to cause the output of the differential to follow the rotation of the control rod and screw. The control rod is driven by the control motor to command output of kinetic energy from the device. 
         [0010]    In a second exemplary embodiment, a kinetic energy storage device comprises first and second counter-rotating flywheels, each coupled to a differential that allows kinetic energy to be transferred to and from the flywheels. A control mechanism comprising a hydraulic motor at each flywheel and a hydraulic actuator commanding each motor is connected to a control mechanism in each flywheel so that movement of the hydraulic motors varies the moment of inertia of the flywheel. A feedback mechanism coupled between the output of the differential and the control mechanisms acts to adjust the moments of inertia of the flywheels when the difference in angular velocities between the flywheels is not zero. 
         [0011]    In another exemplary embodiment, a spin-up fixture is provided to allow kinetic energy to be added to the kinetic energy storage device. In yet another exemplary embodiment the kinetic energy storage device is coupled to a vehicle axle assembly. 
         [0012]    Additional aspects of the invention, together with the advantages and novel features appurtenant thereto, will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned from the practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a perspective view of a kinetic energy storage device having first and second counter-rotating flywheels coupled to a differential in accordance with a first exemplary embodiment of the present invention. 
           [0014]      FIG. 2  is a partial side perspective view of the kinetic energy storage device of  FIG. 1  showing the internal components of the flywheels. 
           [0015]      FIG. 3  is a close-up perspective view of the second flywheel of the device of  FIG. 2  with the fly-weights in a retracted position. 
           [0016]      FIG. 4  is a close-up perspective view of the second flywheel of the device of  FIG. 2  with the fly-weights in an extended position. 
           [0017]      FIG. 5  is a close-up perspective view of the differential of the kinetic energy storage device of  FIG. 1 . 
           [0018]      FIG. 6  is a perspective view of the opposite end of the differential of  FIG. 5 . 
           [0019]      FIG. 7  is a partial view of the differential of  FIG. 5 , showing the control screw portion of the control mechanism. 
           [0020]      FIG. 8  is an exploded view of the differential of  FIG. 7 . 
           [0021]      FIG. 9  is a perspective view of the kinetic energy storage device of  FIG. 1  mounted in a spin-up fixture. 
           [0022]      FIG. 10  is a perspective view of the kinetic energy storage device of  FIG. 1  contained in a housing and mounted in a vehicle. 
           [0023]      FIG. 11  is a perspective view of a portion of a kinetic energy storage device in accordance with a second exemplary embodiment of the present invention showing the movable mass portion in a retracted position. 
           [0024]      FIG. 12  is a perspective view of the device of  FIG. 12  showing the movable mass portion in an extended position. 
           [0025]      FIG. 13  is a perspective view of the kinetic energy storage device of  FIG. 11  further including a case. 
           [0026]      FIG. 14  is a perspective view of the hydraulic rotary actuator portion of the control mechanism of the device of  FIG. 11 . 
           [0027]      FIG. 15  is an exploded view of the rotary actuator of  FIG. 14   
           [0028]      FIG. 16  is a perspective view of a portion of a kinetic energy storage device having dual flywheels coupled to a differential in accordance with a second exemplary embodiment of the present invention. 
           [0029]      FIG. 17  is an exploded view of the differential of the device of  FIG. 16   
           [0030]      FIG. 18  is a perspective view of a kinetic energy storage device in accordance with a second exemplary embodiment of the present invention. 
           [0031]      FIG. 19  is an exploded view of the device of  FIG. 18  showing the flywheel/differential assembly, a control mechanism, an electric drive motor, and a sealed vacuum enclosure. 
           [0032]      FIG. 20  is a top perspective view of a variable-inertia adjusting assembly for use with the device of  FIG. 18 . 
           [0033]      FIG. 21  is a bottom perspective view of the adjusting assembly of  FIG. 20 . 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     First Exemplary Embodiment 
       [0034]    Looking first to  FIG. 1 , a kinetic energy storage device in accordance with an exemplary embodiment of the present invention is depicted generally as  10 . The kinetic energy storage device comprises first and second variable inertia flywheels  12 ,  14  arranged concentrically along a common axis  16 , with a differential  18  positioned there between. The flywheels are configured to rotate in opposite directions (i.e., counter-rotating flywheels) and are each coupled to epicyclic differential  18  which allow the transfer of kinetic energy to or from the flywheels. A control mechanism for varying the inertia of the flywheels comprises a control rod  20  that extends along axis  16 , through each of the flywheels and through differential  18 . As will be explained in more detail below, control rod  20  is coupled to a control hub in each flywheel to allow adjustment of the moment of inertia of each flywheel in response to a transfer of kinetic energy. 
         [0035]    As also seen in  FIG. 1 , each flywheel includes a housing  22   a ,  22   b  and a cover  24   a ,  24   b  to enclose and protect the fly-weights and other components of the flywheel. Housings  22   a ,  22   b  and covers  24   a ,  24   b  further serve to contain the components of the flywheels in the event of breakage or damage. 
         [0036]    With reference to  FIGS. 2 ,  3 , and  4 , each flywheel  12 ,  14  comprises four spindle blocks  26   a ,  26   b ,  26   c ,  26   d  arranged around axis  16  in a concentric, sectioned cylindrical configuration, with spaces between adjacent blocks. Elongated flyweight stems  28   a ,  28   b ,  28   c ,  28   d  are pivotally attached in the spaces between each adjacent pair of spindle blocks via a pin extending through an aperture in the stem and into corresponding apertures in the spindle blocks. Thus, the distal ends of stems  28   a ,  28   b ,  28   c ,  28   d  pivot about the pin in the spaces both inwardly (towards the axis) and outwardly (away from the axis). Flyweights  30   a ,  30   b ,  30   c ,  30   d  are attached at the distal end of each corresponding stem. A control linkage  32   a ,  32   b ,  32   c ,  32   d  extends between each corresponding stem and a common control hub  34 , with opposite ends of the linkage pivotally attached to the stem and hub, respectively. 
         [0037]    As best seen in  FIGS. 3 and 4 , control hub  34  is attached to control rod  20  so that moving the control rod linearly (i.e., along axis  16 ) likewise moves the hub along axis  16 . With the control linkages  32   a ,  32   b ,  32   c ,  32   d , stems  28   a ,  28   b ,  28   c ,  28   d  and flyweights  30   a ,  30   b ,  30   c ,  30   d  attached and configured as described previously, it can be seen that control rod  26  is used to move control hub  34  so as to retract and extend the flyweights towards and away from the axis. As seen in  FIG. 3 , with the control hub  34  moved or pushed away from the spindle blocks  26   a ,  26   b ,  26   c ,  26   d , the flyweights  30   a ,  30   b ,  30   c ,  30   d  are retracted toward the axis. Similarly, with the control hub  34  pulled toward the spindle blocks, the flyweights are extended away from the axis. Thus, the moment of inertia of the flywheel is adjusted using control rod  26  to control the position the flyweights. As also shown in  FIG. 2-4 , each flywheel  12 ,  14  includes a flywheel hub  36   a ,  36   b , coupling the flywheel to the differentia, with the differential sandwiched between the flywheel hubs. Flywheel hubs  36   a ,  36   b  preferably include apertures for receiving fasteners to releasably attach the hubs to the flywheels. 
         [0038]    It should be understood that the exemplary embodiment described is illustrative, and not limiting, and that variations of the configuration shown and described are within the scope of the present invention. For example, while the flywheel is shown with four sections (four spindle blocks, four stems, four control linkages, and four flyweights), other configurations, such as three or five sections could be used. Similarly, the positioning and lever ratio of the control linkage and stems could be varied to provide greater or lesser movement of the flyweights in response to a given movement of the control hub. These and other variations will be apparent to those skilled in the art, and are within the scope of the present invention. 
         [0039]    Looking to  FIGS. 5 and 6 , epicyclic differential  18  comprises a generally cylindrical, planetary body  38  having an integral drive belt pulley  40  configured to receive a drive belt to transfer kinetic energy to and from the differential. First and second input/output gears  42   a ,  42   b  are affixed to opposite sides of the differential and attach to the respective flywheel hubs  36   a ,  36   b  through ball bearing couplers  44   a ,  44   b . Flywheel hubs  36   a ,  36   b  thus couple each of the flywheels  12 ,  14  to the differential so that kinetic energy from the flywheels is transferred to the differential, and conversely, so that kinetic energy from the differential is transferred to the flywheels through the input/output gear/flywheel hub arrangement. 
         [0040]    As seen best in  FIG. 5 , the first side of differential  18  (i.e., the side of the differential positioned adjacent to first flywheel  12 ) includes a first planetary gear  46  positioned to mesh with and engage first input/output gear  42   a  so that turning either of the gears causes the other to likewise turn. Planetary gear  46  is further positioned to mesh with and engage reversing gear  48  which drives a shaft extending through the differential to another planetary gear  50  (shown in  FIG. 6 ) located on the opposite side of the differential, that planetary gear  50  in engagement with second input/output gear  42   b . It should be understood that reversing gear  48  is not engaged with first input/output gear  42 , but only with planetary gear  46 , and thus serves only to transfer and reverse rotation from one side of the differential to the other. As seen in  FIGS. 5 and 6 , an identical second planetary gear/reversing gear arrangement is positioned on the opposite side of (approximately one-hundred eighty degrees around) the input/output gears. 
         [0041]    With the differential configured as just described, it can be seen that rotation of first input/output gear  42   a  turns planetary gear  46  and reversing gear  48 . That rotation is carried to planetary gear  50  on the opposite side of the differential and to second input/output gear  42   b . Thus, flywheel rotation on one side of the differential is transferred to rotation in the opposite direction on the other side of the differential. Preferably, the gear ratio between the first and second sides of the differential is approximately 1:1, although variations from that ratio are accommodated by the present invention. Further, other configurations and arrangements of the gearing may be employed without deviating from the present invention. Additionally, while the exemplary embodiment described is an epicyclic differential, it should be understood that other types of differentials may be used and are anticipated by the present invention. 
         [0042]    Looking to  FIGS. 7 and 8 , the innermost portion of differential  18  houses a threaded control screw  52  engaged within a similarly-threaded control nut  54 . Control nut  54  attaches within a cylindrical receptacle  56  concentric to the center axis of the differential, with fasteners  58  attaching the nut to the differential hub  60 . With the control screw  52  and nut  54  affixed to the differential  18  as shown in  FIG. 7 , it can be seen that rotation of the planetary body  38  of the differential rotates the affixed control nut  54  which drives control screw  52 . Thus, control screw  52  is moved inwardly or outwardly along the axis of the differential, depending on the direction of rotation of the planetary body. Opposite ends of control screw  52  are configured to couple to control rod  20  (as described above) so that control screw  52  is in-line with control rod  20 . Alternatively, control screw  52  could be formed integrally with control rod  20 . 
         [0043]    With reference to  FIGS. 1-8 , in operation, flywheels  12 ,  14  are initially spun-up using a spin-up fixture (described in more detail below) so that each flywheel has an initial stored kinetic energy. A control motor (not shown) is coupled to control rod  20  to provide commands to the control mechanism by rotating control rod  20 . Control rod  20  is in turn coupled to the control hub  34  of each flywheel, with control screw  52  in-line with the control rod. With the moments of inertia of both flywheels equal, their angular velocity is equal. Thus, the angular velocity of the planetary body  38  of the differential  18  (i.e., the output of the device) is zero. Any difference in the angular velocities of the flywheels results in an angular rotation of the planetary body, which in turn causes a rotation of the control nut  54  attached to the center of the differential. Rotation of the control nut drives control screw  52  which moves control rod  20  along its axis, which in turn moves the control hubs  34  of each flywheel to adjust the moment of inertia of the flywheel until they are equal and the difference in angular velocities drops to zero. Thus, the control screw/control rod/control hub mechanism acts as a feedback loop between the two flywheels to maintain the proper moments of inertia such that the differential output follows the rotation of the control rod and screw, as commanded by the control motor driving the control rod. It should be understood that the control/feedback mechanism also acts to account for any inaccuracies or mismatches in the device. For example, while the gear ratio of the planetary and reversing gears of the differential is preferably 1:1, a slight variance in that ratio will be automatically adjusted for by the control mechanism when that variance causes a slight difference in angular velocities. Thus, the kinetic energy storage device of the present invention provides a robust adaptable system. 
       Spin-Up Fixture 
       [0044]    Looking to  FIG. 9 , a spin-up fixture for providing initial kinetic energy to the kinetic energy storage device of the present invention is shown as  62 . Fixture  62  includes a base  64  connected to vertically extending walls  66   a ,  66   b  connected by a top platform. Electric motors  70   a ,  70   b  are attached to the fixture and connect via drive belts  72   a ,  72   b  to a clutch mechanism  74   a  coupled to each flywheel  12 ,  14 . Each electric motor  70   a ,  70   b  is used to spin up the respective flywheel  12 ,  14  with an initial kinetic energy. As described above, the control and feedback mechanism is operable to equalize the angular velocities of the flywheels and to command the output or input of the differential. Preferably, the kinetic energy storage device is spun-up immediately prior to installation in its intended use, such as a vehicle. 
       Vehicle Use 
       [0045]      FIG. 10  depicts a kinetic energy storage device in accordance with an exemplary embodiment of the present invention  10  in use with a vehicle  92 . Preferably, a drive shaft or drive belt extends between the planetary body of the differential of the device to a similar pulley on the axle assembly of the vehicle. Alternatively, the kinetic energy storage device may be connected to the vehicle through a transmission or vehicle differential. These and other alternatives will be apparent to those skilled in the art and are within the scope of the present invention. 
       Second Exemplary Embodiment 
       [0046]    A kinetic storage device in accordance with a second exemplary embodiment of the present invention is depicted in  FIG. 11-21 . 
         [0047]    Looking first to  FIGS. 11 and 12 , a flywheel assembly includes two masses  10   a, b , each hinged to a rotating arm  11 . Arm  11  is attached to a shaft  14  having internal splines  16  at opposite ends of the shaft. Masses  10   a ,  10   b  are attached to bearing pairs  18   a, b  and  18   c, d  at approximately the midpoint of their length. The bearings function as cam followers, riding in grooves  8   a, b , in plates  12   a, b . The grooves are shaped to cause the mass to rotate about the hinged-axis of bar  11 . When bar  11  is caused to rotate in relation to plates  12   a, b , the masses are forced to rotate about the hinges-axis of bar  11 . The center-of mass (COM) of each of the two masses follow a path from a position extremely close to the axis of rotation of the flywheel assembly to a position extremely away from the axis of rotation, thereby varying the inertia of the flywheel assembly  17  according to the equation I=Iq+(2*(Im+(M*k2))), where I is the inertia of the flywheel assembly  17 , Iq is the inertia of the non-adjustable rotating components  12 ,  13 ,  14 ,  15 , Im is the inertia of each moveable mass  10   a, b , M is the mass of the moveable masses  10   a, b , and  k  is the distance of the center-of-mass of each mass to the axis of rotation of the flywheel assembly. 
         [0048]    Each pivoting mass  10   a, b  includes two cam-follower bearings  18   a, b  for mass  10   a  and  18   c, d  for mass  10   b . The cam follower bearings follow a track  8   a, b  in cam plates  12   a, b . The cam plates are held rigidly together by being fixed to drum  15  and back plate  13 . Shaft  14  with bar  11  is rotatable about the axis of rotation of the flywheel assembly  30   a, b  and may be angularly displaced relative to drum  15  and cam plates  12   a, b . This displacement, or phase shift, causes each of the pivotable masses  10   a ,  10   b  to rotate about the hinged pivot point on bar  11 , thereby changing their center-of-mass radii and varying their moment of inertia. This phase shift and consequential inertia shift is affected by a hydraulic rotary actuator  20 . The body of rotary actuator  20  is rigidly attached to the drum/plate  15 ,  13 ,  12   a ,  12   b . The output shaft  21  of the rotary actuator mates with the internal spline  16  of shaft  14 . Output shaft  21  is driven by an internal vane  24  contained in a sealed housing  26  with walls  25   a, b . When hydraulic fluid is introduced to the chambers created by these walls form the rotary union  28 , the vane and shaft are caused to rotate relative to the housing  26 , thus driving the pivoting masses  10   a ,  10   b  to a new position. The entire assemblies  30   a, b  are affixed on radial ball bearings  31  with bearing clamps  32  to the lower half of the vacuum housing  57 . The hydraulic rotary union  28  is held fixed rotationally allowing the connection of two hydraulic lines  51  to ports  22 ,  23 . These lines are subsequently connected to a hydraulic control unit  60  that will operate according to external electrical commands and cause an adjustment in the relative positions of the masses of both the flywheel assemblies. 
         [0049]    Each flywheel assembly  30   a, b  is connected via the internal spines  16  of shaft  14  to input/output splines  41 ,  42  of the differential  40 . A bevel gear  46  is rigidly attached to the differential housing  44  which is free to rotate. Rotational torque is applied to the flywheel pairs by applying torque to the bevel gear  46 . Also, torque from the flywheel pairs is applied to an external load via bevel gear  46 . In the exemplary embodiment depicted, an electric drive motor  54  is mounted to the vacuum housing  57 ,  58 . The output shaft for the motor is coupled via a centrifugal clutch  56  to an input bevel gear  55  which is mesh engagement with the input/output bevel gear  46  of the differential  40 . Thus, the electric motor can drive the flywheel assemblies and also apply torque to the output shaft  59 . 
         [0050]    The control head  60  is a slave-follower mechanism that incorporates mechanical feedback, thus providing a closed-loop output speed control. Feedback from the kinetic energy storage device is taken from its output shaft  59  via belt  61  which rotates a laterally restrained nut  68 , thereby acting to move the control screw  69 . The control motor  64  drives a positioning screw  65  which is mechanically coupled to two hydraulic cylinders  63   a, b , each one connected via hydraulic lines  51  to the rotary actuators  20   a, b  associated with each flywheel assembly. The connections to each flywheel assembly are crossed in a manner that causes the corresponding movement of each pair of masses to be opposite. Therefore, as the first flywheel assembly has masses that are extending away from the center of rotation, the opposing flywheel assembly has masses moving closer to the center of rotation. Thus, the moment of inertia of the first flywheel assembly is increasing while the moment of inertia of the second flywheel assembly is decreasing. While the control motor is in its most central position (“neutral”), the hydraulic control cylinders are also in their central neutral position, and the moments of inertia of both flywheels are equal, and hence their angular velocity is equal. This would cause the angular velocity of the output gear  46  to be zero. If, however, due to inaccuracies or mis-calibration, a small angular rotation exists, since it is coupled to the control nut  68  of the control unit  60 , it will drive the position of the control screw  65  and consequently the position of the two hydraulic cylinders  63   a,b  in a direction opposing he angular velocity of the output of the differential gear  46 . This feedback therefore will always drive the control screw towards zero rotation. 
         [0051]    The operation is thus that the control motor  64  creates an angular rotation command and the output gear  46  of the kinetic energy storage device will follow this command. The hydraulic control cylinders are subjected to pressure caused by the centrifugal force of their rotating masses. Since they are connected in an opposing manner, the associated force of the cylinder rods of the cylinders  63   a ,  63   b  will balanced. However, the centrifugal forces of the masses are non-linear and it is therefore only by the correct shaping of the actuating cam grooves  8   a, b  in the cam plates  18   a ,  18   b  that the balance is achieved by linearizing the associated hydraulic pressures. 
         [0052]    From the foregoing it will be seen that this invention is one well adapted to attain all ends and objectives herein-above set forth, together with the other advantages which are obvious and which are inherent to the invention. 
         [0053]    Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matters herein set forth or shown in the accompanying drawings are to be interpreted as illustrative, and not in a limiting sense. 
         [0054]    While specific embodiments have been shown and discussed, various modifications may of course be made, and the invention is not limited to the specific forms or arrangement of parts and steps described herein, except insofar as such limitations are included in the following claims. Further, it will be understood that certain features and sub combinations are of utility and may be employed without reference to other features and sub combinations. This is contemplated by and is within the scope of the claims.