Abstract:
A vehicle energy harvester including a subunit having an upper surface forming a roadway surface; a vehicle activated treadle on the subunit, the vehicle activated treadle moveable between a first position in which an upper surface of the treadle is at an angle with respect to the upper surface of the roadway surface and a second position in which the upper surface of the treadle is flush with the upper surface of the roadway surface; a generator that generates power in response to movement of the vehicle activated treadle from the first position to the second position and from the second position to the first position; and a capacitor coupled to the generator, the capacitor storing power generated by the generator.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present invention claims the benefit of U.S. Provisional Patent Application No. 61/147,747, filed Jan. 27, 2009, and entitled “TRANSIENT ABSORBER FOR POWER GENERATION SYSTEM”, U.S. Provisional Patent Application No. 61/147,748, filed Jan. 27, 2009, and entitled “WEATHER RESPONSIVE TREADLE LOCKING MEANS FOR POWER GENERATION SYSTEM”, U.S. Provisional Patent Application No. 61/147,749, filed Jan. 27, 2009, and entitled “LOW PROFILE, SURFACE-MOUNTED POWER GENERATION SYSTEM”, U.S. Provisional Patent Application No. 61/147,750, filed Jan. 27, 2009, and entitled “VEHICLE SPEED DETECTION MEANS FOR POWER GENERATION SYSTEM”, U.S. Provisional Patent Application No. 61/147,752, filed Jan. 27, 2009, and entitled “RECIPROCAL SPRING ARRANGEMENT FOR POWER GENERATION SYSTEM”, and U.S. Provisional Patent Application No. 61/147,754, filed Jan. 27, 2009, and entitled “LOSSLESS SHORT-DURATION ELECTRICAL STORAGE MEANS FOR POWER GENERATION SYSTEM”, the entire contents of which are incorporated herein by reference in their entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention is directed toward devices and methods of harvesting vehicle energy, and more specifically, toward a power generation system for harvesting vehicle energy having a substantially lossless short-duration electrical storage means. 
       BACKGROUND OF THE INVENTION 
       [0003]    Very few devices that capture energy from passing vehicles have been implemented, despite numerous designs put forth by various parties over the years. Issues of efficiency, reliability, and manufacturability, among others, have limited the practicality of vehicle energy harvesting devices. Added to the challenge is the variability of vehicle sizes, speeds, axle configurations, and lane positions, all of which can greatly influence the operation of a device trying to capture the motion energy of vehicles and convert it into a useful form of energy. 
         [0004]    Therefore, a need exists for an energy capture device and method having improved efficiency, reliability, and manufacturability, as well as practicality. A need also exists for an energy capture device and method that takes into account the variability of vehicle sizes, speeds, axle configurations, and lane positions in converting the captured motion energy of vehicles into a useful form of energy. 
       SUMMARY OF THE INVENTION 
       [0005]    These problems and others are addressed by the present invention, which provides a novel vehicle energy harvester that overcomes many of the issues with the conventional devices and is therefore better suited for real-world implementation than the conventional devices. 
         [0006]    The exemplary embodiments of the invention make productive use of the energy that is normally wasted (in the form of heat) in reducing the speed of motor vehicles on exit ramps, toll plazas etc., etc. The vehicle energy harvester can absorb mechanical energy from passing (or breaking) vehicles and convert the mechanical energy to electrical energy using, for example, shaft driven generators. 
         [0007]    The disclosed embodiments provide a vehicle energy harvester and power generation system that is simple to install, provides a short payback period, and has a scalable configuration. More particularly, the disclosed embodiments can provide a simple and reliable mechanical configuration that can withstand severe environments. The low cost configuration of the system may provide for faster payback of the expense of the system, and therefore, make the system more practical and desirable for practical applications. 
         [0008]    Additionally, the ease with which the system can be installed also may make the system more practical and desirable for practical applications. The disclosed embodiments require little or no excavation and can be installed in a few hours, instead of over several days as with conventional devices. 
         [0009]    The disclosed embodiment also can provide a scalable configuration that may be particularly advantageous for use at locations, such as exits ramps, toll plazas, hills, among other locations. 
         [0010]    An embodiment also can include monitoring the status or operation of the unit, either periodically or 24 hours per day, seven days per week, using for example, a wireless link or other wired or wireless communication device. 
         [0011]    The exemplary embodiments improve the durability of the system under practical use scenarios. The embodiments of the invention are capable of withstanding the stresses placed upon the system during normal use. 
         [0012]    The exemplary embodiments also can improve the conversion efficiency and reduce the maintenance and operating costs of the system by providing a substantially lossless short-duration electrical storage means. 
         [0013]    An exemplary embodiment of the invention is directed to, for example, a vehicle energy harvester comprising a subunit having an upper surface forming a roadway surface; a vehicle activated treadle on the subunit, the vehicle activated treadle moveable between a first position in which an upper surface of the treadle is at an angle with respect to the upper surface of the roadway surface and a second position in which the upper surface of the treadle is flush with the upper surface of the roadway surface; a generator that generates power in response to movement of the vehicle activated treadle from the first position to the second position and from the second position to the first position; and a capacitor coupled to the generator, the capacitor storing power generated by the generator. 
         [0014]    Another exemplary embodiment of the invention is directed to, for example, a vehicle energy harvester comprising a plurality of subunits each having an upper surface forming a roadway surface; a plurality of vehicle activated treadles on the plurality of subunits, each of the plurality of vehicle activated treadles moveable between a first position in which an upper surface of the treadle is at an angle with respect to the upper surface of the roadway surface and a second position in which the upper surface of the treadle is flush with the upper surface of the roadway surface; and a plurality of generators that generate power in response to movement of each of the plurality of vehicle activated treadles, and a plurality of capacitors coupled to the plurality of generators, the plurality of capacitors storing power generated by the plurality of generators. 
         [0015]    Another exemplary embodiment of the invention is directed to, for example, a vehicle energy harvester comprising a subunit having an upper surface forming a roadway surface; a vehicle activated treadle on the subunit, the vehicle activated treadle moveable between a first position in which an upper surface of the treadle is at an angle with respect to the upper surface of the roadway surface and a second position in which the upper surface of the treadle is flush with the upper surface of the roadway surface; a generator that generates power in response to movement of the vehicle activated treadle from the first position to the second position and from the second position to the first position; and short-duration electrical storage means, coupled to the generator, for storing power generated by the generator. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    These and other aspects and features of embodiments of the present invention will be better understood after a reading of the following detailed description, together with the attached drawings, wherein: 
           [0017]      FIG. 1  is a schematic top view of a power absorber unit of an exemplary vehicle energy harvester. 
           [0018]      FIG. 2  is a schematic perspective view illustrating a portion of an exemplary vehicle energy harvester. 
           [0019]      FIG. 3  is a schematic illustrating a low-loss power conversion system of an exemplary vehicle energy harvester. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    The present invention now is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
         [0021]    Referring now to the drawings,  FIGS. 1-4  illustrate exemplary embodiments of a vehicle energy harvester. 
         [0022]    The exemplary embodiments can make productive use of the energy that is normally wasted (in the form of heat) in reducing the speed of motor vehicles on exit ramps, toll plazas etc., etc. The vehicle energy harvester can absorb mechanical energy from passing (or breaking) vehicles and convert the mechanical energy to electrical energy using, for example, shaft driven generators. Other means for converting the mechanical energy to electrical energy also are contemplated. In an exemplary embodiment, the electric power from the generators can be converted, metered, and fed into the commercial power grid. In another exemplary embodiment, each site can be equipped with wireless communications to monitor the status and/or output of the system. 
         [0023]    Power Absorber Configuration 
         [0024]    The disclosed embodiments can include individual assemblies with integral generators. Other generator configurations also are possible, such as separate generators. 
         [0025]    As shown in  FIG. 1 , the vehicle energy harvester unit  10  can be a low-profile surface mounted assembly. The vehicle energy harvester unit  10  can include an entry ramp  12  and an exit ramp  14 . The vehicle energy harvester unit  10  can include a plurality of subunits  16  having a top surface or driving surface  17 . Each subunit can include one or more vehicle activated treadles  18 . In an embodiment, each subunit  16  can include a generator unit  20 . 
         [0026]    In other embodiments, the vehicle energy harvester unit  10  can be set into the road surface. The surface mounted assembly may require minimal installation effort. Additionally, the unit count can be scaled to road/breaking needs. In an embodiment, each generator unit  20  can feed a common power summing/conversion unit  22 . A simple cable interconnect  24  can be provided to connect each generator unit  20  to the common power summing/conversion unit  22 . A fail safe configuration can protect the system against individual unit failures. 
         [0027]    Power Conversion Unit 
         [0028]    In a disclosed embodiment, the individual absorber units  16  can be connected via cable assemblies  24 . The input power can be summed and applied to a low-loss inverter unit. The power can be converted immediately to a form that is transmittable to the power grid. The output can be metered and applied to the power grid for transmission. 
         [0029]    Absorber Unit Operation 
         [0030]    With reference to  FIG. 2 , an exemplary embodiment of a subunit  16  of a vehicle energy harvester unit  10  can include spring-loaded treadles  18  having a treadles gear  30  engaging a drive gear  32 . The drive gear  32  is coupled to a shaft  34 . In operation, one or more vehicle tires force the spring-loaded treadles  18  down as they roll over the treadles  18 . The treadle gears  30  drive the plurality of drive gears  32 , which rotate the shaft  34 . The shaft  34  winds a torsion spring  36 , thereby absorbing the treadle drive transient. A pawl can lock the shaft  34  as rotation ends. The torsion spring  36  rotates a flywheel  38 , thereby spreading the impulse of the treadle drive over time to extend output to a generator  40 . The flywheel  38  can turn a generator  40 , such as a hydro pump. The generator  40 , in turn, can generate electric power for sale/use/storage. 
         [0031]    Lossless Short-Duration Electrical Storage Means 
         [0032]    With reference to  FIG. 3 , exemplary embodiments for providing improved short-duration electrical storage of the power generated by the vehicle energy harvester unit  10  will now be described. 
         [0033]    Commonly, many electrical conversion devices available use batteries as a storage means for storing the electric power generated by an energy harvester. Since the exemplary embodiments of the vehicle energy harvester unit  10  are highly modular and each treadle subunit  16  creates a relatively small amount of electric power during individual impacts, high capacity capacitors (e.g.,  50 ) can be implemented as a storage device, as exemplarily shown in  FIG. 4 . Such capacitors (e.g.,  50 ) can provide important benefits of being nearly lossless (e.g., lossless or substantially lossless). Additionally, the frequency with which such capacitors (e.g.,  50 ) may need to be replaced during the life of the system can be minimized or eliminated all together. In contrast, conventional systems using batteries may need to be replaced periodically throughout the life of the system, resulting in increased maintenance and operational costs. 
         [0034]    In an exemplary embodiment, each treadle subunit  16  can create and store an electric charge each time a vehicle passes over the system and activates the treadle  18 . This charge can be stored in a suitably sized capacitor (e.g.,  50 ). The capacitor (e.g.,  50 ) can be connected via a simple cable assembly to a central harvesting unit, which receives and combines the output with the outputs from other treadle assemblies (e.g., subunits  16 ). 
         [0035]      FIG. 3  schematically illustrates an exemplary low-loss power conversion system  100 . With reference to  FIGS. 1-3 , the operation of the exemplary low-loss power conversion system will now be described. 
         [0036]    In operation, the weight of an oncoming vehicle(s) forces the treadle  17  downward. The system converts the downward movement of the treadle  17  to a rotational force at the permanent magnet alternator (PMA)  40 . The PMA  40  converts the mechanical force to electric power. The output of the PMA  40  can be rectified by a rectifier assembly  52  and used to charge an electrical storage device or devices  50 , such as one or more high capacity capacitors. A micro-controller unit (MCU) (not shown) can be provided to control power conditioning circuits  54  to provide constant output to an inverter unit  56 , such as a high efficiency inverter. The inverter unit  56  can convert the input power to AC power in the proper form, for example, for resale to a local utility company (e.g.,  60 ). The output power can be metered (e.g.,  58 ) for billing and administrative uses, etc. (e.g.,  62 ). 
         [0037]    By providing a substantially lossless short-duration electrical storage means (e.g.,  50 ), the exemplary embodiments provide important advantages of improving the conversion efficiency of the system as well as reducing the maintenance and operating costs of the system, among other things. 
         [0038]    The present invention has been described herein in terms of several preferred embodiments. However, modifications and additions to these embodiments will become apparent to those of ordinary skill in the art upon a reading of the foregoing description. It is intended that all such modifications and additions comprise a part of the present invention to the extent that they fall within the scope of the several claims appended hereto. 
         [0039]    Like numbers refer to like elements throughout. In the figures, the thickness of certain lines, layers, components, elements or features may be exaggerated for clarity. 
         [0040]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well-known functions or constructions may not be described in detail for brevity and/or clarity. 
         [0041]    As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. As used herein, phrases such as “between X and Y” and “between about X and Y” should be interpreted to include X and Y. As used herein, phrases such as “between about X and Y” mean “between about X and about Y.” As used herein, phrases such as “from about X to Y” mean “from about X to about Y.” 
         [0042]    It will be understood that when an element is referred to as being “on”, “attached” to, “connected” to, “coupled” with, “contacting”, etc., another element, it can be directly on, attached to, connected to, coupled with or contacting the other element or intervening elements may also be present. In contrast, when an element is referred to as being, for example, “directly on”, “directly attached” to, “directly connected” to, “directly coupled” with or “directly contacting” another element, there are no intervening elements present. It will also be appreciated by those of skill in the art that references to a structure or feature that is disposed “adjacent” another feature may have portions that overlap or underlie the adjacent feature. 
         [0043]    Spatially relative terms, such as “under”, “below”, “lower”, “over”, “upper”, “lateral”, “left”, “right” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, elements described as “under” or “beneath” other elements or features would then be oriented “over” the other elements or features. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the descriptors of relative spatial relationships used herein interpreted accordingly.