Abstract:
A system and method to convert the ram air energy resulting from the movement of an electric vehicle through the air mass into electric energy to recharge the energy storage devices of the vehicle while minimizing the apparatus caused drag effect on the vehicle, thereby extending the driving range of the vehicle between external charging. At least one ram air driven turbine is positioned within the vehicle, the turbine driving a mechanically coupled generator to charge the battery. Ram air is ducted in the front of the vehicle to cause the turbine generator to rotate and output electrical energy to charge the battery. The effect of variation in vehicle speed on both turbine generator output and turbine caused drag is optimized by adjusting the pitch angle of the turbine blades. At least one included ultra capacitor will implement a pre-programmed charge/discharge profile to reduce charge resistance electrical loading on the turbine generator and enable continued battery charging with minimal increase of turbine caused drag.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of PPA Ser. No. 61/132,997, filed 2008 Jun. 25 by the present inventor. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     REFERENCE TO SEQUENCING LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX 
     Not applicable 
     BACKGROUND OF THE INVENTION 
     The present invention relates to an electrically powered motor vehicle and, specifically, to a ram air driven turbine generator charging system for the vehicle that utilizes control of both turbine torque and electrical loading at the generator output to charge the vehicle battery and power the vehicle while minimizing the turbine caused drag resistance of the vehicle. 
     Prior art describes wind powered electric generator systems mounted on the roof, the hood or internal to an electric vehicle to charge the vehicle battery while the vehicle is in motion (Guenard, 2002/0066608, 2002; Deets, U.S. Pat. No. 7,135,786, 2006; Maberry, U.S. Pat. No. 7,147,069, 2006; Burns, U.S. Pat. No. 5,760,515, 1998, for example). The prior art also describes air flow management systems including both fixed and variable shroud configurations purported to control or eliminate drag resistance associated with turbine systems. The many embodiments in prior art do not consider adequately the fundamental issues inherent in converting and storing the ram air kinetic energy developed by a vehicle in motion, that is, (a) the ram air energy necessary to cause the turbine generator to rotate manifests as additional vehicle drag which, if vehicle speed is to be maintained, must be overcome by the application of additional traction drive energy and; (b) as the vehicle battery approaches full charge, the increased electrical load on the generator increases which increases the torque load on the turbine, adding to the turbine caused drag resistance. Prior art devices to control battery charge resistance affect on generator load are effective but slow acting and not efficient. The two effects are limiting in any attempt to achieve a functionally useable result in converting and storing the ram air energy of a moving electric vehicle that, in normal use, operates in a wide range of speeds and battery charge levels. It is necessary for the charging system to be effective and efficient at both low and high speeds over a range of battery charge levels. The present embodiment resolves these issues and thereby extends significantly the driving range of an electric vehicle between times that it becomes necessary to charge the vehicle by external means. 
     What is needed in the art is an electric vehicle, including at least one ram air driven turbine generator and at least one ultra capacitor auxiliary energy storage device, that controls turbine generator caused drag by managing turbine generator torque and battery charge resistance. This will provide for sufficient battery charging energy and vehicle power to extend the driving range of the vehicle between external battery charges. 
     BRIEF SUMMARY OF THE INVENTION 
     The present embodiment provides for a ram air powered battery charging system, including ultra capacitor assist, that will extend significantly the driving range of an electrically powered vehicle beyond that otherwise achieved before external charging is required. The embodiment maintains the desired charging current to the battery while minimizing the ram air turbine caused drag resistance of the vehicle at most vehicle speeds and levels of battery charge. 
     The embodiment primarily relates to, but is not limited to, an electrically powered automobile with an assembly positioned in the forward compartment that has mounted in it at least one but essentially a plurality of ram air driven turbines each mechanically coupled to and driving a separate electric generator. An aerodynamic intake and air chamber configuration directs ram air to cause rotation of the turbine generator devices and another air chamber conveys exhaust air out of the vehicle through at least one discharge port. Ram air created by the moving vehicle impinges on the turbine blades of the turbine generators causing them and their coupled generator rotors to rotate and cause an electric current to flow in the generators. The angle, or pitch, of the turbine blades relative to the direction of ram air flow is variable and computer controlled. Electrical output of the generators is modified, regulated and routed through wiring and cabling, as in prior art, to components of the charging system under control of a central processor to charge the battery. Generator output energy that is excess to that required for charging the battery is distributed and routed to power the traction drive motor and other electrical components of the vehicle as needed. 
     This embodiment includes the means to vary the angular position, or pitch, of the turbine blades relative to the direction of ram air flow to ensure maximum harvest of ram air kinetic energy at low speeds while controlling turbine speed, generator output and turbine caused drag resistance at highway speeds. A further embodiment includes programmed control of a variable air gap between stator and rotor of the generator, as in prior art, to enhance management of turbine torque and generator output. This embodiment also includes a programmed charging profile, obtained through ultra capacitor technology, to maintain a pre-determined level of electrical load at the generator outputs as the battery approaches full charge. By efficiently maintaining an optimum electrical load on the turbine generator, the opposing torque load on the turbine is kept at a level that allows efficient battery charging to continue at an appropriate rate with minimal increase in turbine caused drag. The ultra capacitor also provides short term power boost to the traction drive motor for vehicle acceleration. These capabilities together provide sufficient management of battery charging performance and turbine caused drag to extend vehicle driving range. 
     The main advantage of the embodiment is that it will enable continuous ram air driven battery charging of an electric vehicle during most vehicle speeds and levels of battery charge while maintaining acceptable levels of turbine caused drag, thereby efficiently converting the kinetic energy of ram air flow, developed by a powered vehicle in motion, to generate and store electrical energy. The present embodiment will extend the driving range of an electrically powered vehicle between times that battery charging by external means is required. 
     Another advantage of this embodiment is that it will provide capacitor stored energy for surge power during acceleration. 
     Another advantage of this embodiment is that it will fit many configurations of modern vehicles with little change to basic body and frame design. 
     Another advantage of this embodiment is that it enables reduction of turbine noise at highway speeds. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The features and advantages of the present embodiment as well as its development and operation will be clarified by reference to the following description of the embodiments as they pertain to the associated drawings: 
         FIG. 1  is a perspective drawing of an electrically powered vehicle including the present embodiment in a typical installation; 
         FIG. 2  is a top view of the vehicle of  FIG. 1  showing one positioning of the major components of the embodiment; 
         FIG. 3  is a side view of the of the vehicle of  FIG. 1 ; 
         FIG. 4  is several views of the turbine generator mounting assembly of  FIG. 1 ; 
         FIG. 5  is several views of the turbine generator device of  FIG. 4 ; 
         FIG. 6  is a detail view of the hub and blade portion of the turbine generator device of  FIG. 5  showing angular change of the turbine blades; 
         FIG. 7  is a system block diagram of the present embodiment; 
         FIG. 8  is a partial schematic of the charging system showing one embodiment of the ultra capacitor connectivity between the vehicle battery, traction drive motor and the turbine generator output interface; 
         FIG. 9  is a flow chart of system operation. 
     
    
    
     Reference characters indicate corresponding parts throughout the figures. The descriptions herein illustrate one preferred embodiment of the invention in the form shown and are not to be construed as limiting the scope of the invention in any way. 
     REFERENCE NUMERALS 
     
         
           11  vehicle 
           12  turbine generator mounting assembly 
           13  traction drive motor 
           14  vehicle battery 
           15  power management unit 
           21  front air intake grills 
           22  intake air chamber 
           23  upper discharge port 
           24  exhaust air chamber 
           31  lower discharge space 
           32  front compartment rear wall 
           40 - 44  turbine generators 
           46  turbine generator mounting bracket 
           50  turbine generator plenum housing 
           51  turbine 
           52  turbine blades 
           53  turbine hub 
           54  generator 
           55  plenum mounting braces. 
           70  central processor 
           71  ultra capacitor 
           72  power management module 
           73  regenerative energy source 
           74  solar panel energy source 
           75  vehicle accessories 
           80  ultra capacitor variable charge profile circuitry 
           81  system isolation/protection circuitry 
       
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows the major electrical components of the embodiment as typically installed in an electrically powered vehicle  11 . Turbine generator mounting assembly  12 , containing turbine generators  40 ,  41 ,  42 ,  43 ,  44 , is fixed in a forward position in the front compartment of the vehicle, mounted to the frame and body of the vehicle. Electric traction drive motor  13  will be typically mounted in the front compartment. Vehicle battery  14  is shown for illustration in the rear of the vehicle and may be a multiple cell battery or a set of such batteries comprising a battery pack. One battery or pack is shown in this embodiment but in an alternative embodiment two separate and equivalent batteries are used with one an active drive energy source and the other a ‘hot’ spare being charged by the ram air charging system. When the active battery reaches a pre-programmed minimum level of charge, the batteries are electrically switched and their roles reversed thereby further extending the vehicle driving range. Power Management Unit (PMU)  15  contains a central processor and regulating, control and conditioning electronics, known in prior art, to manage the charging system. Front grills  21  provide ram air intake to the intake air chamber  22  and turbine generator mounting assembly  12 . Upper exhaust air discharge port  23  provides venting of exhaust air to ambient space. 
     Referring to  FIG. 2 , the aerodynamically configured intake  21  and air chamber  22  direct ram air flow to mounting assembly  12 . The ram air intake  21  is similar to modern vehicle front grills with grill elements configured to stabilize air flow as it enters the air chamber  22 . Chamber  22  is affixed and sealed to the vehicle body at front and sides of the front compartment and to the forward surface of assembly  12 . Ram air from forward intake grill  21  impinges the blades of the turbine generator devices  40 ,  41 ,  42 ,  43 ,  44  mounted in assembly  12  causing them to rotate and output an electric current to charge the battery and power other vehicle electrical components. 
     Referring to  FIG. 2  and  FIG. 3 , exhaust air chamber  24  shown is one embodiment of exhaust air flow ducting to upper discharge ports  23  and lower exhaust space  31 . The primary concern is the avoidance of back pressure on the turbine blades from exhaust air which will impact turbine efficiency. Exhaust air management in the forward compartment maintains a wide flow area  24  immediately to the rear of mounting assembly  12  similar to the open space configuration of the engine compartment of most modern automobiles. The rear or firewall  32  of the engine compartment is slightly convex in the vertical plane to direct exhaust air to discharge to ambient space  31  beneath the engine compartment and to the upper discharge ports  23  of the vehicle. An alternate embodiment will add exhaust air vents at both sides of the rear of chamber  24  to increase air flow to ambient space. This configuration provides cooling air to components located in the vehicle forward compartment. 
       FIG. 3  side view of vehicle  11  further clarifies component placement and air flow management. 
       FIG. 4  is four views of the turbine generator mounting assembly  12  showing one placement of the plurality of turbine generator devices  40 ,  41 ,  42 ,  43 ,  44 . Mounting assembly  12  is a rigid material of sufficient strength to accept the weight and road shock stress of said turbine generator devices without distortion. This shows five (5) turbine generators but the number and size may vary according to charging requirements and system efficiency achieved. The separation of turbine generator mounting openings in assembly  12  shall be the minimum consistent with good practice for strength and shock and vibration durability in order to maximize the flow-through performance of the assembly and minimize the drag baseline of the embodiment. Devices  40 ,  41 ,  42 ,  43 ,  44  are mounted in spaced openings in assembly  12  and secured against road shock by bracket  46 . The method of mounting assembly  12  in a vehicle will vary according to specific forward compartment configuration but attachment points will be at strength points of the chassis, frame and body of the vehicle. Remaining descriptions will consider a single turbine generator device since all five shown are alike.  50 ,  52 ,  53  and  55  are integral to the turbine generator device and are described in  FIG. 5   
     Referring to  FIG. 5 , turbine generator device  40  is comprised of plenum housing  50 , turbine  51 , a plurality of turbine blades  52 , hub  53 , generator  54  and mounting braces  55  that are integral to device  40 . Turbine blades  52  attach to hub  53  that is directly coupled to the rotor axis of generator  54  so that ram air caused rotation of the turbine blades  52  rotates the rotor of generator  54  and causes current to flow in the generator. Hub  53  contains electro-mechanical means to change the angle, or pitch, of the turbine blades relative to the direction of ram air flow from a position of maximum ram air force on the blades and consequent maximum torque and rotational speed of the generator rotor to a position of minimum torque and rotational speed. This enables maximum harvest of ram air energy during low speed travel of the vehicle and, at highway speeds, allows control of torque, rotation speed, generator output and turbine, blade noise while allowing effective battery charging to continue and cooling air to flow in the vehicle. Variable pitch turbine generators are known in prior art. The present embodiment further incorporates the program control means to adjust selectively the pitch angle of each set of turbine generator blades to provide additional control of the combined turbine generator outputs and total turbine caused drag. Hub  53  and generator  54  are shrouded to form an aerodynamic shape typical of direct drive wind generators. The preferred embodiment of generator  54  is a permanent magnet, axial flux generator or alternator of known design for reasons of light weight, efficiency and versatility, however, this embodiment is not meant to limit, in any way, the selection of the generator or alternator to be used. Application of the axial flux generator enables the further ability, noted herein and in prior art, to manage generator torque and output by varying the rotor-stator air gap of the generator. Changing the air gap changes the magnetic flux density acting on the rotor and thereby can be used to adjust the torque load and electrical output of the generator. 
     In  FIG. 6 , turbine blade  52  angular change at hub  53  has incremental step positions. 
       FIG. 7  is a system block diagram of the charging system. Bus  76  provides addressable connectivity to the system components. The Power Management Unit (PMU)  15  is shown as a dotted line block in order to illustrate its major components—Central Processor  70 , Ultra Capacitor  71  and Power Conditioning Module  72 . The Central Processor  70  is programmed to provide sensing and control of ultra capacitor  71  charge/discharge, turbine blade angle adjustment and, if included, generator air gap control. Battery  14  is shown as a single block but may be one or two battery packs as described herein. Drive motor  13 , Regenerative Energy Source  73 , Solar Panel  74  and Accessories  75  are included to illustrate the integration of the present embodiment with the electrical system of the vehicle. 
       FIG. 8  is a simplified schematic of ultra capacitor (UC)  71  connectivity to show that its connectivity and charge/discharge profile are controlled by Central Processor (CP)  70  as in prior art. A single ultra capacitor is shown to simplify the drawing but a plurality of ultra capacitors is required. Ultra capacitor electrical connectivity between battery  14  and turbine generators is initiated when battery charge level approaches full charge and charge resistance reaches a pre-determined level that would create an unacceptable torque requirement on the turbine generators with consequent increase in turbine caused drag. Ultra capacitor charge and discharge times are much faster than a battery so that the ultra capacitor will maintain an optimum level of charge resistance at the generator outputs while continuing to charge the battery at the rate specified for the type of battery and state of charge. This control technique also serves to extend battery life. Sensing and switching circuitry provides capacitor surge power application to the drive motor as needed. The charge/discharge profile of UC  71  is controlled by CP  70  through application of variable circuitry  80 , known in prior art, to maintain a moderate level of charge resistance load at the generator outputs while charging the battery. The charge circuitry includes isolation and pulse protection components  81 , known in prior art, to protect the battery, drive motor and ultra capacitor to ensure their expected cycle lives. Electrical cabling and wiring of this embodiment are of standard practice for such a vehicle system to meet electrical and signal requirements of component rated specifications as chosen for a particular vehicle design. 
       FIG. 9  is a flow chart of the operation of this embodiment wherein pertinent system data are acquired: current value symbols are shown for simplicity but, in practice, component and system voltages are also measured and integrated in the decision process as well. GsubI are individual generator output currents; CsubI is capacitor charge/discharge current; DsubI is vehicle demand current; BsubI is battery charging/discharging current; BsubC is battery charge level; GsubRPM are rotation speeds of individual turbine generators; CsubC is capacitor charge state; TsubPA are turbine pitch angles; Switch positions and settings of control devices are also monitored. Data are then compared with preprogrammed values. Comparison results are then integrated. Instructions are then sent to appropriate components for actions necessary to maintain system data within programmed limits. The process iterates. 
     Operation 
     The electric vehicle  12 , as it moves forward through the ambient air mass, will cause air to flow at a velocity near the vehicle speed through the intake grill  21  into air chamber  22 . Resulting ram air will impinge the blades of turbine generators  40 - 44  causing them and generator(s)  54  to rotate and an electric current to flow in the generators and the charging system. Air will flow through the turbine blades  52  into exhaust air chamber  24  and out exhaust port  23  and exhaust space  3 . Generated electric current is connected through circuitry controlled by Central Processor  70  to recharge vehicle battery  14  and power traction drive motor  13  and accessories  75 . 
     The dynamic resistance of the turbine generators to air flow is manifest as additional vehicle drag. This drag increases proportional to vehicle speed and requires expenditure of additional drive energy to maintain vehicle speed. The objective of this embodiment is to ensure that turbine generated electrical energy exceeds the turbine drag induced traction drive energy at most vehicle speeds. In so doing battery charge level is maintained over extended time and the driving range of the electric vehicle between external charging is increased. Turbine blades  52  are variable in pitch angle relative to air flow direction. Central processor ( 70 ) monitors blade pitch angle, generator RPM and output and system current demand and distribution. It will adjust pitch angle to optimize these parameters and minimize turbine caused drag at different vehicle speeds. Typically, turbine blade angle will be maximum at lowest vehicle speeds and reduce as speed is increased and ram air flow velocity is high. 
     Additional turbine induced dynamic drag is caused by system resistance to current flow seen as additional electrical load at the generator outputs. The primary cause is battery charge resistance at high levels of battery charge. This increases the opposing torque load on the turbine generator and, again, manifests as additional drag. Central processor  70  monitors battery charge level, generator output and RPM and system current flows and initiates a programmed charge/discharge profile by the ultra capacitor to maintain a moderate electrical load at the generator output while enabling continued battery charging and current distribution. 
     The embodiment as described herein is a preferred design, however, said embodiment can be changed within the spirit and scope of this description. This application is intended to cover any variations, applications or adaptations of the embodiment using its general principles of managing charging performance and turbine caused drag. This application is meant to cover any departures from the present description that come within known or customary practices in the art to which this embodiment pertains and fall within the limits of appended claims. 
     CONCLUSION, RAMIFICATIONS AND SCOPE 
     Accordingly, the reader will see that at least one embodiment provides a reliable means to harvest efficiently the ram air energy generated by a moving electric vehicle to extend the driving range of the vehicle and reduce the frequency of required external re-charging of the vehicle energy storage devices. 
     The embodiment maintains an optimum ratio of the turbine generated energy to the drive energy expended to minimize turbine caused aerodynamic drag of the vehicle. Therefore, precise management of turbine generator performance and vehicle power distribution in varying speed and charge state conditions is achieved:
         The pitch angle of turbine blades is variable enabling precise control of both generator output and turbine caused drag at most vehicle speeds.   The air gap between generator rotor and stator is variable in some generators which, if needed, further enhances control of turbine generator performance.   The ultra capacitor component of the embodiment, through its rapid charge/discharge characteristic, enables charging to continue even at a high battery charge level by de-coupling the charge resistance effect from the generator output. The turbine generator can then continue to operate at an optimum output/drag level proportional to vehicle speed and output can be distributed to other vehicle components. The ultra capacitor is a source of surge power for acceleration.       

     Although the description above contains many specifics, these should not be construed as limiting the scope of the embodiment but as merely providing illustration of some of the presently preferred embodiments reflecting currently available technology. For example, the turbine generator can be a generator or alternator of many designs, configurations and materials. The turbine generator assembly can be installed in any reasonable location that will provide maximum effectiveness for a given vehicle configuration. The battery and ultra capacitor can be of different types, even redundant with active and stand by elements. 
     Thus the scope of the embodiment should be determined by the appended claims and their legal equivalents rather than by the examples given.