Abstract:
An electricity generating shock absorber includes a coil assembly having a length of electrically conducting material wrapped around an outside perimeter, and along a length, of a hollow tube formed of electrically resistant material; a magnet unit formed of at least one annular axial magnet; a central shaft having a magnetic reluctance on which a plurality of the magnet units are mounted, the central shaft dimensioned for insertion through a central opening of the at least one annular axial magnet, the central shaft combined with the plurality of magnet units forming a magnet assembly dimensioned to slideably insert into a central cavity of the hollow tube; and a cylindrical shell having a first end attached to a terminal end of the magnet assembly, the cylindrical shell extending a length of the magnet assembly, the cylindrical shell having an inner diameter sized to slideably accommodate an outside diameter of the coil assembly.

Description:
PRIORITY CLAIM 
     The present disclosure claims benefit of U.S. Provisional Patent Application No. 61/368,846, filed on Jul. 29, 2010, for “ELECTRICITY GENERATING SHOCK ABSORBERS,” the entire contents and disclosure of which, are expressly incorporated by reference herein as if fully set forth herein. 
    
    
     TECHNICAL FIELD 
     The present disclosure is generally related to energy recovery. Specifically, the present disclosure is related to regenerative suspension systems. 
     BACKGROUND 
     Among all the sources of pollutants in the atmosphere, the transportation industry generally is a significant contributor. For example, in the United States, the transportation industry consumes a majority of the crude oil, much of which is used by automobiles. Hence, any advances in energy efficiency, especially in the transportation industry, may correspondingly lead to reduction in energy consumption, which not only cumulatively decreases energy costs, but also cumulatively contributes to a greener environment and greater energy independence and security. 
     Increasing demand for better fuel economy has led to improvements and developments in hybrid vehicles, electric vehicles and vehicles powered by fuel cells or diesel fuel. Efforts on the part of the automotive industry to increase fuel economy have included, but are not limited to, reductions in vehicle mass, improved aerodynamics, active fuel management, direct injection engines, homogeneous charge compression ignition engines and hybrid engines. Still, other mechanisms, techniques and energy sources that will improve fuel economy are continually being sought. 
     Currently, about 10 to 16% of the available fuel energy is used to drive an automobile, overcoming the friction and drag force from the road and wind. Besides engine cycle efficiency, one important mechanism of energy loss in automobiles is the dissipation of kinetic energy during vehicle vibration and motion. In the past hundred years, the automotive industry has been working hard to dissipate the motion and vibration energy into waste heat by optimal design of braking and suspension systems and by employing active controls, such as anti-lock braking systems or active suspensions. During the past ten years, energy recovery from braking has achieved great commercial success in hybrid vehicles. However, regenerative vehicle suspensions, which have the advantage of continuous energy recovery, have generally not come into practice due to various factors, such as insufficient vibration control, unsatisfactory energy harvesting, prohibitive costs, high complexity, practical incompatibility and relative inefficiency. 
     In view of the foregoing, it would be desirable to provide a regenerative vehicle suspension technology that takes into account the aforementioned factors. 
     BRIEF SUMMARY 
     An exemplary embodiment of the disclosed technology is directed to an electricity generating shock absorber comprising: a coil assembly having a length of electrically conducting material wrapped around an outside perimeter, and along a length, of a hollow tube formed of electrically resistant material; a magnet unit formed of at least one annular axial magnet; a central shaft having a magnetic reluctance on which a plurality of the magnet units are mounted, the central shaft dimensioned for insertion through a central opening of the at least one annular axial magnet, the central shaft combined with the plurality of magnet units forming a magnet assembly dimensioned to slideably insert into a central cavity of the hollow tube; and a cylindrical shell having a first end attached to a terminal end of the magnet assembly, the cylindrical shell extending a length of the magnet assembly, the cylindrical shell having an inner diameter sized to slideably accommodate an outside diameter of the coil assembly. 
     An exemplary embodiment of the disclosed technology is directed to a method of manufacturing an electricity generating shock absorber, the method comprising: at least once, winding a coil around a hollow tube having an electrical resistance; stacking a first pair of permanent magnets on a shaft having a magnetic reluctance; adapting the stacked shaft to be moveable in relation to a hollow cavity of the hollow tube; attaching the shaft to a first base; separating the first pair of magnets between each other on the shaft by a first magnetically-permeable spacer; aligning the first pair of magnets with like-poles facing each other; and encapsulating at least a part of the wound coil via a concentric outer cylinder attached at one end to the first base. 
     An exemplary embodiment of the disclosed technology is directed to a method of using an electricity generating shock absorber for generating electricity, the method comprising: moving a magnet assembly in relation to a coil assembly, the coil assembly comprising: a coil at least once wound around a hollow tube having an electrical resistance and a hollow cavity, the magnet assembly comprising: a first pair of permanent magnets stacked on a shaft having a magnetic reluctance, the shaft attached to a first base, the first pair of magnets separated between each other on the shaft by a first magnetically-permeable spacer, the first pair of magnets aligned with like-poles facing each other; and a concentric outer cylinder encapsulating at least a part of the coil assembly, the cylinder attached at one end to the first base. 
     An exemplary embodiment of the disclosed technology is directed to electricity generating shock absorber comprising: a first case comprising: a rack attached to the inner surface of the first case; and a second case comprising: a pinion in contact with the rack and attached to the inner surface of the second case via a first shaft mounted on a first base, a bevel gear box comprising a first and second bevel gear in contact with each other, the first bevel gear mounted on the first shaft, the second gear mounted on a second shaft coupled via a coupler to a rotational motor attached to the inner surface of the second case. 
     An exemplary embodiment of the present invention is directed to a method for generating electricity from mechanical vibrations, the method comprising: providing an electricity generating shock absorber having a magnet assembly including a first pair of magnets stacked horizontally along a shaft constructed of magnetic reluctant material and a coil assembly including a coil wound around a hollow tube having an electrical resistance, the first pair of magnets aligned with like-poles facing each other, the first pair of magnets, an insertion end of the magnet assembly being slidably inserted into an open end of the hollow tube of the coil assembly, a concentric outer cylinder encapsulating at least a part of the coil assembly, the cylinder attached at a base end of the magnet assembly opposite the insertion end; coupling a closed end of the hollow tube to a first mass; coupling the base end of the magnet assembly to a second mass, the electricity generating shock absorber providing vibration dampening between the first mass and the second mass; inducing relative motion between the magnet assembly and the coil assembly to generate electromotive voltage in the coil; and capturing the electromotive voltage. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objects, features and advantages of the disclosed technology will become apparent to a skilled artisan in view of the following detailed description taken in combination with the attached drawings, in which: 
         FIG. 1   a  symbolically illustrates an exemplary embodiment of a linear electromagnetic shock absorber; 
         FIG. 1   b  symbolically illustrates a cross-section view of an exemplary embodiment of a magnet assembly; 
         FIG. 2  symbolically illustrates an exemplary embodiment of a single layer electricity generating shock absorber with radial magnets; 
         FIG. 3  symbolically illustrates an exemplary embodiment of a double layer electricity generating shock absorber; 
         FIG. 4  symbolically illustrates an exemplary embodiment of a gear-based electricity generating shock absorber; and 
         FIG. 5  symbolically illustrates an alternative arrangement of the magnets of the electromagnetic embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As used herein, a vehicle is a device that is designed or used to transport people or cargo. Vehicles may be land-based, such as automobiles, buses, trucks, trains, or marine-based, such as ships, boats, or aeronautical, such as airplane, helicopter, spacecraft. 
     As used herein, a shock absorber is an energy dissipating device generally used in parallel with the suspension spring to reduce the vibration generated by surface irregularities or during acceleration and braking. 
     While, for simplicity and clarity, the following description of the figures is described in reference to land-based vehicles, the disclosed technology is not limited to land-based vehicles. Rather, the disclosed technology may be implemented and used with any device that is designed or used to transport people or cargo. 
       FIG. 1   a  symbolically illustrates an exemplary embodiment of a linear electromagnetic shock absorber and  FIG. 1   b  symbolically illustrates a cross section view of an exemplary embodiment of a magnet assembly. 
     As shown in  FIG. 1   a , a regenerative shock absorber  100  is in a configuration of a linear induction generator. In an exemplary embodiment, shock absorber  100  includes a magnet assembly  110  moveable in relation to a coil assembly  120 . In an exemplary embodiment, shock absorber  100  includes a coil assembly  120  movable in relation to a magnet assembly  110 . In an exemplary embodiment, magnet assembly  110  and coil assembly  120  are both movable in relation to each other. 
     In an exemplary embodiment, shock absorber  100  works in two cycles—a compression cycle and an extension cycle. In an exemplary automotive implementation where coil assembly  120  is attached to an automobile&#39;s frame and magnet assembly  110  is attached to the automobile&#39;s suspension system, the compression cycle occurs as coil assembly  120  moves downward and the extension cycle occurs as magnet assembly  110  moves upward (the relative movement of the coil and magnet assemblies  110  and  120  may be different upon a different configuration). Thus, if the compression cycle controls the motion of the vehicle&#39;s unsprung weight, then extension controls the motion of the heavier, sprung weight. Consequently, via alternation of cycles, due to, for example, road irregularities or during acceleration and braking, shock absorber  100  converts a kinetic energy of suspension vibration between an automobile wheel and a sprung mass into useful electrical power, as further described below. 
     In an exemplary embodiment, magnet assembly  110  is composed of ring-shaped, i.e. annular, permanent magnets  111  separated by ring-shaped high magnetically permeable spacers  114  stacked on a shaft  113  of high reluctance material. In an exemplary embodiment, the material is aluminum. In an exemplary embodiment, magnets  111  are rare-earth permanent magnets. In an exemplary embodiment, spacers  114  are steel spacers. In an exemplary embodiment, magnet assembly includes 12 magnets  111  and  13  spacers  114 . 
     As illustrated in  FIG. 1   b , magnets  111  are arranged with like-poles of adjacent magnets  111  facing each other to redirect a magnetic flux in a radial direction. A concentric outer cylinder  112  made of high magnetically permeable material is used to protect the coils and reduce the reluctance of magnetic loops, to further increase magnetic flux density in the coils i.e. in order to further “pull” the magnetic flux outward. 
     Coil assembly  120  is composed of coils  121  wound around a tube  122  having a high electrical resistance. In an exemplary embodiment, coils  121  are composed of copper and tube  122  is composed of polyoxymethylene. In an exemplary embodiment, the height of one coil is equal to half of the total height of magnet  111  and spacer  114 . In an exemplary embodiment, coils  121  align with magnet assembly  110 . In an exemplary embodiment, the total number of coils  121  is 16. In an exemplary embodiment, coils  121  are connected to a rectifier set-up. 
     In an exemplary embodiment, power generated in shock absorber  100  is related to the total volume of coils  121 . However, voltage is related with the winding of coils  121  around tube  122 . In an exemplary embodiment where the total volume of coils  121  is constant and coils  121  with a small diameter are used, then more windings of coils  121  are expected, thus generating a higher voltage. In an exemplary embodiment, coils  121  are wound in a range between 250 and 300 turns, which generates about 10V of output voltage. 
     In an exemplary embodiment, all the coils together will form a four-phase design where the 0 degree and 180 degree phases generate maximum positive and negative voltages and the 90 degree and 270 degree phases have zero voltage. Although the voltage or power of each phase may depend on the relative position of coil assembly  120  in the magnetic field, the total power generation does not. As coils  121  vibrate in relation to the magnetic field created by magnet assembly  110 , an electromotive force is generated, thus producing electricity. Also, the electromotive force serves as a damping force to reduce the vehicle vibration. In an exemplary embodiment, shock absorber  100  maintains a constant performance of power generation for movement (compression and extension cycles) between about 2 to about 4 inches. 
     For example, when shock absorber  100  is placed in an automobile suspension system, vibrations in the suspension system, due to road irregularities or during acceleration and braking, cause the coil assembly  120  to move in relation to the magnetic assembly  110  i.e. compression and extension cycles, thus generating an electromotive force, which can then be used to recharge the automobile&#39;s battery. In an exemplary embodiment, the peak output voltage is inversely proportional to the square of coils  121  diameter and the peak power depends on the total volume of conducting material in the coils. 
       FIG. 2  symbolically illustrates an exemplary embodiment of a single layer electricity generating shock absorber, where radial magnets are used to increase the magnetic flux density. 
     In an exemplary automotive implementation, shock absorber  200  converts a kinetic energy of suspension vibration between a wheel and a sprung mass into useful electrical power. In an exemplary embodiment, shock absorber  200  includes a magnet assembly  210  movable in relation to a coil assembly  220  in direction V. In an exemplary embodiment, shock absorber  200  includes a coil assembly  220  movable in relation a magnet assembly  210  in direction V. In an exemplary embodiment, magnet assembly  210  and coil assembly  220  are both movable in relation to each other. 
     In an exemplary embodiment, magnet assembly  210  is composed of radial magnets  211 . a  and axial magnets  211 . b  stacked on a shaft  213  of high reluctance material. In an exemplary embodiment, the material is aluminum. In an exemplary embodiment, the magnets are rare-earth permanent magnets. In an exemplary embodiment, shaft  213  is attached to a first base  224 . In an exemplary embodiment, a first mounting ring  215  is attached to first base  224 . In an exemplary embodiment, mounting ring  215  connects to an axle, near an automotive wheel, i.e., the unsprung weight. 
     As further exemplarily illustrated in  FIG. 2 , radial magnets  211 . a  and axial magnets  211 . b  are arranged with like-poles of adjacent magnets  211 . a  and  211 . b  facing each other to redirect a magnetic flux in clockwise and counter-clockwise directions  216 . In an exemplary embodiment, a concentric outer cylinder  212  made of high magnetically permeable material is used to protect the coils and reduce the reluctance of magnetic loops, to further increase magnetic flux density in the coils i.e. in order to further “pull” the magnetic flux outward. 
     Coil assembly  220  is composed of coils  221  wound around a tube  222  having a high electrical resistance. In an exemplary embodiment, coils  221  are composed of copper and tube  222  is composed of polyoxymethylene. In an exemplary embodiment, tube  222  is connected to a second base  225 . In an exemplary embodiment, a second mounting ring  223  is attached to second base  225 . In an exemplary embodiment, second mounting ring  223  connects to an automobile frame, i.e., the sprung weight. In an exemplary embodiment, coils  221  are connected to a rectifier set-up. 
     For example, when shock absorber  200  is placed in an automobile suspension system, vibrations in the suspension system, due to road irregularities or during acceleration and braking, cause the coil assembly  220  to move in relation to the magnetic assembly  210  i.e. compression and extension cycles, thus generating an electromotive force, which can then be used to recharge the automobile&#39;s battery. In an exemplary embodiment, the relative motion generates alternating current (“AC”). The generated AC passes through a rectifier and via a rectification process gets converted to direct current (“DC”). Subsequently, a power converter, such as a DC to DC converter, is used to maintain a suitable voltage for charging a typical automobile battery. In an exemplary embodiment, shock absorber  200  harvests between about 2 to about 8 W of energy at 0.25-0.5 m/s RMS suspension velocity, which charges a typical car battery in about 7.5 hours. 
       FIG. 3  symbolically illustrates an exemplary embodiment of a double layer electricity generating shock absorber. 
     In an exemplary automotive implementation of the disclosed technology, shock absorber  300  converts a kinetic energy of suspension vibration between a wheel and a sprung mass into useful electrical power. In an exemplary embodiment, shock absorber  300  includes a magnet assembly  310  moveable in relation to a coil assembly  320  in direction V. In an exemplary embodiment, shock absorber  300  includes a coil assembly  320  movable in relation to a magnet assembly  310  in direction V. In an exemplary embodiment, magnet assembly  310  and coil assembly  320  are both movable in relation to each other. 
     In an exemplary embodiment, magnet assembly  310  is composed of double layers (inner and outer) of radial magnets  311 . a  and axial magnets  311 . b  stacked on a shaft  313  of high reluctance material. In an exemplary embodiment, the material is aluminum. In an exemplary embodiment, the magnets are rare-earth permanent magnets. In an exemplary embodiment, shaft  313  is attached to a first base  324 . In an exemplary embodiment, a first mounting ring  315  is attached to first base  324 . In an exemplary embodiment, mounting ring  315  connects to an axle, near an automotive wheel, i.e., the unsprung weight. 
     Double layers of radial magnets  311 . a  and axial magnets  311 . b  are arranged with like-poles of adjacent magnets  311 . a  and  311 . b  facing each other to redirect a magnetic flux in clockwise and counter-clockwise directions  316 . In an exemplary embodiment, as coils  321  vibrate in relation to and between double layers of radial magnets  311 . a  and axial magnets  311 . b , a magnetic flux, which has increased power density over an exemplary embodiment described in  FIGS. 2   a  and  2   b , is generated. In an exemplary embodiment, a concentric outer cylinder  312  made of high magnetically permeable material is used to protect the coils and reduce the reluctance of magnetic loops, to further increase magnetic flux density in the coils i.e. in order to further “pull” the magnetic flux outward. 
     Coil assembly  320  is composed of coils  321  wound around a tube  322  having a high electrical resistance. In an exemplary embodiment, coils  321  are composed of copper and tube  322  is composed of polyoxymethylene. In an exemplary embodiment, the polyoxymethylene tube is connected to a second base  325 . In an exemplary embodiment, a second mounting ring  323  is attached to second base  325 . In an exemplary embodiment, second mounting ring  323  connects to an automobile frame, i.e., the sprung weight. In an exemplary embodiment, coils  321  are connected to a rectifier set-up. 
     For example, when shock absorber  300  is placed in an automobile suspension system, vibrations in the suspension system, due to road irregularities or during acceleration and braking, cause the coil assembly  320  to move in relation to the magnetic assembly  310  i.e. compression and extension cycles, thus generating an electromotive force, which can then be used to recharge the automobile&#39;s battery. 
     Alternatively, the arrangement of radial and axial magnets, shown in  FIGS. 2   a ,  2   b  and  3 , are arranged as shown in  FIG. 5 . Specifically, radial rare-earth magnets  502  are dimensioned to be thinner than the radial magnets disclosed above with respect to  FIGS. 2   a ,  2   b  and  3 . Spacers  504 , constructed of a material having high magnetic permeability such as iron, are stacked onto the radial rare-earth magnets  502  so that the stacked assembly of the radial rare-earth magnet  502  and the spacer  504  has the same height as adjacent axial magnets  506 . In other words, the annular radial magnet  502  includes an inlayed spacer  504 , having an annular shape. The cross-sectional aspect of the combination of radial magnet  502  and spacer  504  is identical to the cross-sectional aspect of the axial magnet  506  in that the central opening diameter and the outside diameter of the combined radial magnet  502  and spacer  504  is the same as the respective diameters of the axial magnet. 
     The radial rare-earth magnets  502 , Axial magnets  506  and spacers  504  are positioned between an aluminum shaft  508  and linearly disposed coils  510  similar to the arrangement shown in  FIGS. 2   a  and  2   b . Moreover, in the double layer embodiment of  FIG. 3 , the radial rare-earth magnets in both layers can be replaced with the stacked assembly shown in  FIG. 5 . 
     The stacked assembly of the radial rare-earth magnet  502  and the spacer  504 , shown in  FIG. 5 , advantageously similar or even higher magnetic density than a full height radial rare-earth magnet at a significantly reduced cost. The advantages are obtained because iron has a greater permeability than rare-earth materials, such as NdFeB, used for rare-earth permanent magnets. Moreover, iron is significantly less expensive than rare-earth permanent magnets. Thus, a cost savings can be realized by using smaller dimensioned radial rare-earth magnets  502  with the spacers  504  over using full height radial rare-earth magnets in the configurations shown in  FIGS. 2   a ,  2   b  and  3 . 
       FIG. 4  symbolically illustrates an exemplary embodiment of a gear-based electricity generating shock absorber. Shock absorber  400  includes an outer case  410  and an inner case  410 . 
     In an exemplary embodiment, outer case  410  includes a toothed rack  413  attached to inner surface of outer case  410  via a first base  412 . A first mounting ring  411  is attached to an outer surface of outer case  410 . 
     In an exemplary embodiment, inner case  420  includes a toothed pinion  424 , which is mounted near a first end of a first shaft  423 , engaging rack  413  for converting linear motion into rotational motion. Hence, since vehicle vibration is periodic linear motion, the vibration is converted into rotational motion via the movement of rack  413  up to the limit of its travel, against pinion  424 , causing pinion  424  to rotate on its axis. First end of first shaft  423  is attached to a base  422  mounted on inner surface of inner case  420 . 
     In an exemplary embodiment, a bevel gear  425 . a  engages a bevel gear  425 . b  within a bevel gearbox  429 . Bevel gear  425 . a  is mounted on a second end of first shaft  423 . Bevel gear  425 . b  is mounted on a second end of a second shaft  426  attached to a rotational motor  428 . As bevel gear  425 . a  transfers rotational motion from rack  413  and pinion  424  to bevel gear  426 . b , rotational motor  428  is driven via a rotation of second shaft  426  about its axis. A coupler  427  attaches motor  428  to second shaft  426 . A second mounting ring  421  is attached to an outer surface of inner case  420 . 
     In an exemplary embodiment, when rotational motor  428  is driven by rack  413  and pinion  424  via bevel gear  425 . a  and  425 . b , rotational motor  428  generates a back electromotive force, thus producing electricity. While in the typical shock absorber, the electromotive force acts as the damping force as the vibration is mitigated by dissipating the vibration energy into heat, shock absorber  400  vibration is mitigated by dissipating the vibration energy into electric energy. 
     Exemplary embodiments of electricity generating shock absorbers maintain or enhance the required suspension damping performance and provide an effective way to adjust the suspension damping according to driver need or road conditions. Furthermore, the vibration mitigation performance is maintained or enhanced since the electricity-generating shock absorbers can provide back electromagnetic force, acting as the damping or control force. Also, exemplary embodiments of electricity generating shock absorbers enable energy harvesting in a typical passenger vehicle estimated to be on the same order of scale as a vehicle alternator as under normal driving conditions. Moreover, the generated power can be used to charge a battery, power the electrical accessories, such as lights or radio, or drive the wheels of a hybrid vehicle. 
     Further, exemplary embodiments of electricity generating shock absorbers enable an easy implementation of regenerative active suspension: a combination of energy harvesting and active suspension control. Additionally, exemplary embodiments of electricity generating shock absorbers are retrofittable, which means it can be used for new cars, or just to replace the traditional viscous shock absorber in the existing cars. 
     It should further be known that the present invention is not limited to application in motor vehicles. Rather, the electricity generating shock absorber can be advantageously utilized in any application where sufficient vibrational forces are present to operate the shock absorbers. In all embodiments, the electricity generating shock absorbers of the present invention are intended to be properly sized to accommodate the loads and forces experienced by the electricity generating shock absorbers in the particular application. Thus, any specific values provided in the disclosure above, are intended for illustrative convenience only and should not be taken as the full range of values acceptable for implementing the present invention. 
     In contrast to other regenerative shock absorbers, exemplary embodiments of electricity generating shock absorbers have high energy density, low weight and good compactness. Unlike ball-screw based systems, exemplary embodiments of electricity generating shock absorber also have little interference with vehicle dynamics.