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.

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 reciprocal spring arrangement. 
       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. The embodiments of the invention recognize that numerous factors may reduce the durability of the system under normal use including, for example, motor vehicles impacting the treadles at highway/freeway speeds of 60 to 70 miles per hour or more, and ice build-up restricting free movement of the treadle assembly, among other things. 
         [0012]    The embodiments of the invention address and solve these problems and improve the durability of a treadle based energy conversion systems according to the embodiments of the invention. The embodiments of the invention also improve the conversion efficiency of the energy conversion systems. 
         [0013]    In order to reduce the wear and tear on the treadle assembly, embodiments of the present invention can include a transient absorption means in the form of a torsion spring. In conventional systems, the treadle drive mechanism is attached directly to an electrical generation means. As a result, high speed vehicle impacts with the treadle assembly will cause undue stress on the mechanical components due to the inertia of the electrical generation means connected to it. The exemplary embodiments of the present invention, for example as shown in  FIG. 1 , reduce the mechanical stress (impulse) on the mechanical components substantially by storing the treadle drive output in a torsion spring which will release its stored energy to the alternator after the vehicle passes over the treadle. 
         [0014]    In order to improve the conversion efficiency, the system can include a conversion unit with multiple treadle units having less intrusive or disruptive portions or components that can absorb the vehicles kinetic energy as gently and quietly as possible. As a result of the less disruptive components of the exemplary system, the actual amount of energy derived from each treadle may be relatively small or reduced compared with more disruptive designs. To address this, exemplary embodiments can improve the efficiency with which the system converts the kinetic energy of one or more passing vehicles into useable power. 
         [0015]    An exemplary embodiment of the invention is directed to, for example, 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. 
         [0016]    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, wherein at least one generator of the plurality of generators generates power in response to movement of one of the plurality of vehicle activated treadles from the first position to the second position and from the second position to the first position. The vehicle energy harvester includes a reciprocal spring arrangement applying a biasing force on at least one of the plurality of vehicle activated treadles to move the at least one of the vehicle activated treadles away from the second position and toward the first position, a treadle gear coupled to the vehicle activated treadle; a drive gear mounted on a rotatable shaft, and a ratchet gear mounted on the rotatable shaft, wherein the rotatable shaft is coupled to the generator, wherein the drive gear engages and is driven by movement of the at least one of the vehicle activated treadles from the first position to the second position; wherein the ratchet gear rotates freely during movement of the at least one of the vehicle activated treadles from the first position to the second position, and wherein the ratchet gear is driven by movement of the at least one of the vehicle activated treadles from the second position to the first position by the reciprocal spring arrangement. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    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: 
           [0018]      FIG. 1  is a schematic top view of a power absorber unit of an exemplary vehicle energy harvester. 
           [0019]      FIG. 2  is a schematic perspective view illustrating a portion of an exemplary vehicle energy harvester. 
           [0020]      FIG. 3  is a schematic side view illustrating a portion of an exemplary vehicle energy harvester. 
           [0021]      FIG. 4  is a schematic perspective view illustrating a portion of an exemplary vehicle energy harvester. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    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. 
         [0023]    Referring now to the drawings,  FIGS. 1-4  illustrate exemplary embodiments of a vehicle energy harvester. 
         [0024]    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. 
         [0025]    Power Absorber Configuration 
         [0026]    The disclosed embodiments can include individual assemblies with integral generators. Other generator configurations also are possible, such as separate generators. 
         [0027]    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 . 
         [0028]    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. 
         [0029]    Power Conversion Unit 
         [0030]    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. 
         [0031]    Absorber Unit Operation 
         [0032]    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. 
         [0033]    Transient Absorption Means 
         [0034]    In order to reduce the wear and tear on the treadle assembly, an exemplary embodiment includes a transient absorption means in the form of a torsion spring  36 , as illustrated in  FIGS. 2 and 4 . In conventional systems, the treadle drive mechanism commonly is attached directly to an electrical generation means. As a result, high speed vehicle impacts with the treadle assembly  18  will cause undue stress on the mechanical components due to the inertia of the electrical generation means (e.g.,  40 ) connected to it. The exemplary embodiments of the present invention, for example as shown in  FIGS. 2 and 4 , reduce the mechanical stress (impulse) on the mechanical components substantially by storing the treadle drive output in a torsion spring  36  which will release its stored energy to the alternator/generator (e.g.,  40 ) after the vehicle passes over the treadle  18 . 
         [0035]    More particularly, the torsion spring  36  can provide advantages of absorbing the impulse imparted by fast-moving vehicles striking the treadles  18 . The torsion spring  36  also can isolate the treadle assembly from mass/inertia of the connected flywheel  38  and alternator/generator (e.g.,  40 ). The torsion spring  36  further can release stored energy to the electrical charging means (e.g.,  40 ) with very little loss. 
         [0036]    As illustrated in  FIG. 3 , in another embodiment, a flexible link  42  can provide a low-cost alternative. In this embodiment, the vehicle striking the treadle  18  forces the treadle  18  to rotate about its hinged end point. The inertia of the charging system (e.g.,  40 ) resists turning of the drive gear  32 . The flexible link  42  can bow (e.g., bend or flex) to absorb impulse then release the energy to the charging system (e.g.,  40 ). 
         [0037]    The exemplary embodiments of the invention recognize that a delicate balance must be maintained between the amount of energy absorbed from a vehicle and the resultant disruption to the vehicle and its occupants. Thus, the practicality and safety of the system configuration can be improved by absorbing the vehicle&#39;s kinetic energy gradually. 
         [0038]    In an exemplary embodiment, the system can include a vehicle energy harvester unit  10  with a plurality of treadle subunits  16  having small (i.e., less intrusive or disruptive) portions or components (e.g., treadles  18 ) that absorb the vehicles kinetic energy as gently and quietly as possible. As a result of the less disruptive nature of the exemplary system, the actual amount of energy derived from each treadle  18  may be relatively small or reduced compared with more disruptive designs. Therefore, the exemplary embodiments of the invention provide further advantages of improving the efficiency with which the system converts the vehicles kinetic energy. Exemplary embodiments that can improve the conversion efficiency of the system are discussed below. 
         [0039]    Reciprocal Spring Arrangement 
         [0040]    With reference to  FIG. 4 , exemplary embodiments for improving the conversion efficiency of the system will now be described. 
         [0041]    As exemplarily illustrated in  FIG. 4 , an exemplary embodiment of the vehicle energy harvester unit  10  can be equipped with a means for moving or returning the treadle  18  back to the active position, such as a reciprocal spring arrangement  44  or assembly. The embodiments recognize that at least a portion of the energy stored in the means (e.g.,  44 ) for moving the treadle  18  back to the active position can be used to continue the generate power, thereby improving the conversion efficiency of the system. One of ordinary skill in the art will recognize that the reciprocating spring assembly  44  or arrangement is not limited to the embodiment illustrated in  FIG. 4 , and that other arrangements can be provided for performing the desired function of moving the treadle  18  back to the active position can be provided. For example, the reciprocating spring  44  can include one or more springs, such as a compression spring, an extension spring, or a torsion spring, among others, as well as other devices that are capable of storing a portion of the energy imparted by the movement of the treadle or moving the treadle  18  back to the active position, such as a lever arm, a cantilever, a pulley system, etc. 
         [0042]    In operation of the exemplary embodiment of  FIG. 4 , the weight of an oncoming vehicle(s) forces the treadle  18  downward. In response to the downward movement of the treadles  18 , one or more drive gears  32  rotate the shaft  34  in a first direction, as indicted by the arrows in  FIG. 4 . The ratchet gear  42  can rotate freely during the downward motion of the treadle  18 . 
         [0043]    As shown in  FIG. 4 , one or more springs (e.g., reciprocating springs  44 ) can be mounted in opposition to the movement of the treadle  18 . When the treadle  18  is actuated by the weight of a passing vehicle, one or more of the springs  44  are compressed. After the vehicle passes over the treadle  18 , the treadle  18  is released from under the weight of the vehicle and the compressed reciprocal springs  44  operate to push the treadle  18  back to the ready position. 
         [0044]    As explained above, the compression of one or more of the springs  44  results in a portion of the energy absorbed from the vehicle being stored in the springs  44 . Thus, the conversion efficiency of the system can be improved by using at least a portion of this stored energy in the reciprocating springs  44  to continue to apply rotational force to the shaft  34 . 
         [0045]    Various systems can be implemented to convert a portion of the energy stored in the reciprocating springs  44  into continued or additional rotational movement of the shaft  34 . For example, as illustrated in  FIG. 4 , during the movement of the treadle  18  back to the ready or active position, one or more ratchet gears  42  can engage in the upward direction and continue to apply rotational force to the shaft  34 . By using the attached ratcheting gear  42  assembly, some of the energy stored in the springs  44  can be used to continue the motion of the permanent magnet alternator (PMA)  40  and thereby provide a backstroke to improve the overall conversion efficiency. Thus, the conversion efficiency of the system can be improved by using at least a portion of the stored energy in one or more of the reciprocating springs  44  to continue to apply rotational force to the shaft  34 . 
         [0046]    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. 
         [0047]    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. 
         [0048]    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. 
         [0049]    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.” 
         [0050]    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. 
         [0051]    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.