Abstract:
An all-electric, wheeled vehicle has a magnet array that can be selectively moved between a retracted position and a deployed position, to respectively operate in a motor mode or a generator mode. When in the motor mode, with its magnet array retracted, wheel rotation to move the vehicle is powered by an onboard battery. Alternately, in the generator mode with the magnet array deployed, the vehicle is powered by a Linear Synchronous Motor (LSM). Specifically, the deployed magnet array interacts with a multiple-phase winding (i.e. LSM) embedded into the roadway on which the vehicle travels. Further, rotation of the wheel during vehicle movement in the generator mode recharges the battery.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention pertains generally to all-electric vehicles. More particularly, the present invention pertains to electric vehicles that are alternately propelled by a battery or a Linear Synchronous Motor (LSM). The present invention is particularly, but not exclusively, useful as an electric vehicle that recharges its battery while being propelled by the LSM. 
       BACKGROUND OF THE INVENTION 
       [0002]    It is well known that electric motors and generators can be respectively used to convert electrical energy into mechanical energy and mechanical energy into electrical energy. Basically, both a motor and a generator operate on related physical principles. They both also involve similar operational structures, namely: a conductor, a magnetic field and an electrical current. On the one hand, for a motor (conversion of electrical to mechanical energy) a conductor is located in a magnetic field and an electrical current is passed through the conductor. Consequently, the magnetic field will exert a force on the conductor. This force can then be mechanically transferred from the conductor to do work (e.g. rotate a wheel on a vehicle). On the other hand, for a generator (conversion of mechanical energy into electrical energy) a conductor is physically moved in a magnetic field. The consequence of this movement is that an electrical current is set up or induced in the conductor. This induced current can then be stored (e.g. recharging a battery). 
         [0003]    A Linear Synchronous Motor (LSM) is a particular type of electrical motor wherein the conductor (e.g. a three-phase winding) is laid out in a substantially linear configuration. The magnetic field is then moved along a path substantially parallel to the layout of the conductor (winding). The resultant force can then be applied to move a vehicle in a direction along the conductor (winding). 
         [0004]    In its configuration, an LSM is noticeably different from the more conventional electric motors that have interactive magnetic fields and conductors. Typically, but not necessarily, the magnetic field in a conventional arrangement is held stationary while the conductor is rotated in the magnetic field. Despite their obvious configuration differences, in all other important aspects the basic physics of an LSM and a conventional electric motor are essentially the same. 
         [0005]    For many applications, and for many different reasons, an electrical power plant (i.e. an electric motor) may be preferable to other types of motors (e.g. a fossil fuel combustion engine). In particular, more and more land vehicles are being equipped with electrical power plants. For example, many automobile manufacturers are providing battery-powered cars. LSMs are also being increasingly considered for use as the propulsion units of trains traveling over extended sections of railway lines. An important consideration for the use of an LSM as a propulsion unit for a vehicle, however, is that it effectively confines travel of the vehicle to the roadways where a stationary component of the LSM (e.g. the conductor/winding) has been pre-positioned. In some applications, however, it may be desirable to avoid such a limitation in favor of a more flexible travel envelope. If so, energy consumption requirements can become a concern. 
         [0006]    In light of the above, it is an object of the present invention to provide an all-electric vehicle that is alternately propelled by two different types of propulsion units (i.e. an LSM and a battery-powered electric motor). Another object of the present invention is to provide an all-electric vehicle that includes controls for selectively operating a motor/generator either as a battery-powered motor to propel the vehicle, or as a generator for recharging the battery while the vehicle is being propelled by an LSM. Still another object of the present invention is to provide an all-electric vehicle that is easy to use, relatively simple to manufacture and comparatively cost effective. 
       SUMMARY OF THE INVENTION 
       [0007]    An all-electric wheeled vehicle in accordance with the present invention is alternately propelled by either of two electric propulsion units. One unit includes an onboard, battery-powered electric motor/generator. The other unit is a Linear Synchronous Motor (LSM) that includes both onboard and external components. In either case, the wheels of the vehicle remain in contact with the roadway on which the vehicle is traveling. 
         [0008]    As intended for the present invention, and depending on which propulsion unit is being used, the motor/generator can be operated in either of two modes (i.e. a motor mode or a generator mode). In the motor mode, the vehicle uses the motor/generator as its propulsion unit with electrical energy from the battery to rotate the wheels of the vehicle for propulsion. Preferably, the motor is a synchronous permanent magnet motor capable of generating around 125 hp at approximately 1200 rpm. Alternately, when the vehicle is being propelled by the LSM, the motor/generator can be operated in its generator mode. In this mode, the rotating wheels of the vehicle interact with the motor/generator to recharge the battery. 
         [0009]    To establish the LSM, the vehicle has an onboard magnet array that can be selectively deployed. When deployed, the magnet array is positioned adjacent the roadway over which the vehicle is traveling, with an air gap of approximately 5 cm therebetween. This then allows the magnetic field of the magnet to interact with an external electric power segment that is embedded into the roadway. For the operation of the LSM, the power segment for the LSM preferably includes a three-phase winding with an electric current provided by an external power source that passes through the winding. At this point, it is noted that the three-phase winding is only exemplary. As will be appreciated by the skilled artisan, different multiple-phase windings can be used, if desired. 
         [0010]    Structurally, the electric motor/generator, the battery (e.g. ultra-capacitors) and a system control for alternately operating the motor/generator in either the motor mode or the generator mode are all mounted on the vehicle&#39;s undercarriage. Further, as implied above, the vehicle is also equipped with a magnet array that is mounted on the undercarriage for movement between a retracted configuration and a deployed configuration. For the present invention, when the magnet array is in its retracted configuration, the vehicle is operated in the motor mode as disclosed above. On the other hand, when the magnet array is deployed, the LSM acts as the propulsion unit for the vehicle and the motor generator recharges the battery. 
         [0011]    In more detail, the magnet array preferably includes a permanent magnet that is mounted on a support member. Further, the support member is preferably a back iron and the permanent magnet is a Halbach array. Importantly, the Halbach array (permanent magnet) is provided to establish a magnetic field that will interact with the current in the three-phase winding of the power segment. Preferably, the LSM operates at approximately 15 Hz and the winding creates an LSM field having a waveform speed along the power segment of approximately 15 mph. As will be appreciated by the skilled artisan, LSM operation at 15 Hz and a waveform speed of 15 mph are exemplary. Correspondingly different LSM frequencies and waveform speeds can be used, if desired. Further, the power train of the vehicle includes a differential that is connected between the wheel and the electric motor, with the differential having an approximately 10.9 to 1 gear ratio. Additionally, a variable frequency inverter-rectifier is connected between the electric motor and the battery for charging the battery with a d.c. voltage when the motor/generator is operated in the generator mode, and for providing an a.c. voltage to energize the electric motor when it is operated in the motor mode. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which: 
           [0013]      FIG. 1  is a perspective view of an all-electric vehicle in accordance with the present invention, with the vehicle shown traveling toward a power segment embedded into the roadway on which the vehicle is traveling; 
           [0014]      FIG. 2  is a block diagram of the electrical system employed by the present invention for the all-electric vehicle; 
           [0015]      FIG. 3A  is a side elevation view of the all-electric vehicle with its magnet array in a retracted configuration, with the magnet array shown in cross section as seen along the line  3 - 3  in  FIG. 1 ; 
           [0016]      FIG. 3B  is a view of the vehicle as seen in  FIG. 3A  with the magnet array in a deployed configuration; and 
           [0017]      FIG. 4  is a representative cross section view of a portion of the magnet array and a portion of the power segment as seen along the line  3 - 3  in  FIG. 1 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    Referring initially to  FIG. 1  an all-electric vehicle in accordance with the present invention is shown and is designated  10 . As shown, the vehicle  10  is a wheeled vehicle that will typically have a plurality of wheels but must necessarily have at least one wheel  12 . As will be appreciated by the skilled artisan, the vehicle  10  can essentially be any kind of wheeled land vehicle known in the pertinent art. The vehicle (tractor)  10  shown in the drawings is only exemplary.  FIG. 1  also indicates that a magnet array  14  is mounted on the vehicle  10  substantially as shown, and that the vehicle  10  carries at least one battery  16 . For purposes of the present invention, the battery  16  preferably includes ultra-capacitors having an electrical energy capability of about eight mega-joules. Note: as a practical matter there may be a plurality of batteries  16  carried on the vehicle  10 .  FIG. 1  also shows that for at least a portion of its travel time, the vehicle  10  is expected to travel along a roadway  18  that includes a power segment  20  which is preferably embedded into the roadway  18 . More specifically, the power segment  20  comprises a three-phase winding  22  that receives an electrical current from an external power source (not shown). 
         [0019]    Referring now to  FIG. 2 , a schematic block diagram of components for the vehicle  10  is shown with the components arranged on an undercarriage  24  of the vehicle  10 . In this arrangement, a wheel  12  of the vehicle  10  is connected to a differential  26  via an axle  28 . In turn, the differential  26  is connected directly to a motor/generator  30 . For purposes of the present invention, the differential  26  preferably has around a 10.9 to 1 gear ratio, and the motor/generator  30  preferably incorporates a permanent magnet motor that operates with approximately 1445 rpm at 15 mph.  FIG. 2  also shows that the motor/generator  30  is connected to an inverter-rectifier  32  via an a.c. line  34 , and that the battery (ultra-capacitor)  16  is connected to the inverter-rectifier  32  via a d.c. line  36 . Further,  FIG. 2  indicates by the dashed-line  38  that a control system  40  onboard the vehicle  10  can be used to alternate the operation of the inverter-rectifier  32  and thereby cause the motor/generator  30  to operate in either a motor mode or a generator mode. 
         [0020]    To operate the motor/generator  30  in its motor mode, the control system  40  is used to direct the inverter-rectifier  32  to convert a d.c. voltage from the battery  16  into an a.c. voltage for operating the motor/generator  30  as a motor. Accordingly, the motor/generator  30  provides power to rotate the wheel  12 . Thus, the motor/generator  30  acts as a propulsion unit for the vehicle  10  when the motor/generator  30  is operated in its motor mode. Alternately, for the motor/generator  30  to operate in its generator mode, the inverter-rectifier  32  is controlled by the control system  40  to convert an a.c. voltage from the motor/generator  30  into a d.c. voltage for recharging the battery  16 . In this generator mode, a rotation of the wheel  12  causes the motor/generator  30  to generate the a.c. voltage that is converted by the inverter-rectifier  32  into the d.c. voltage that recharges the battery  16 . 
         [0021]    As noted above, the vehicle  10  alternately uses two different propulsion units. One propulsion unit is established when the motor/generator  30  is operated in its motor mode as disclosed above. The other propulsion unit is a Linear Synchronous Motor (LSM). Thus, an important aspect of the present invention concerns how a Linear Synchronous Motor (LSM) is established as a propulsion unit for the vehicle  10 . How this is accomplished is best appreciated with reference to  FIGS. 3A and 3B . 
         [0022]    In  FIG. 3A , the magnet array  14  is shown in a retracted configuration wherein the magnet array  14  is effectively distanced from the roadway  18 .  FIG. 3A  also shows that the magnet array  14  includes a permanent magnet  42  that is mounted on a support member  44  that can act as a back iron for the permanent magnet  42 . Additionally, it is seen that the magnet array  14  includes a plurality of vertical clearance wheels, of which the vertical clearance wheel  46  is exemplary. In  FIG. 3B , the magnet array  14  is shown in a deployed configuration wherein the magnet array  14  is deployed (i.e. lowered) toward the roadway  18  until the vertical clearance wheel(s)  46  makes contact with the roadway  18 . With this contact, the permanent magnet  42  of the magnet array  14  is at a distance  48  from the surface of the roadway  18 . Preferably, the distance  48  is approximately five centimeters. For purposes of the present invention, the permanent magnet  42  can be any type magnet well known in the pertinent art, such as a Halbach Array shown in  FIG. 4 . In any event, as indicated in  FIG. 4 , when the magnet array  14  has been deployed it is close enough to the three-phase winding  22  for the magnetic field of the permanent magnet  42  to directly interact with the electric field of the three-phase winding  22 . This interaction then provides a propulsive force for the vehicle  10 . In this arrangement for the LSM, the three-phase winding  22  is preferably operated at about fifteen Hz, to create a waveform speed (i.e. a speed for vehicle  10 ) of about fifteen mph. 
         [0023]    In its operation, the vehicle  10  can travel along the roadway  18  by selectively using either of two propulsion units. The selection, however, is dependent on whether the vehicle  10  is traveling over an embedded power segment  20 . Specifically, when the vehicle  10  is traveling over a power segment  20 , an LSM propulsion unit can be created between the magnet array  14  on the vehicle  10  and the three-phase winding  22  embedded in the roadway  18 . This is done be lowering the magnet array  14  into a deployed configuration (see  FIG. 3B ) as the vehicle  10  approaches the power segment  20 . An engagement of the magnetic field of the magnet array  14  with the electric waveform of the three-phase winding  22  is accomplished by having the speed of the vehicle  10  substantially correspond with the speed of the waveform (e.g.  15  mph). Once established, the LSM can thereafter effectively function as the propulsion unit of the vehicle  10 . 
         [0024]    Importantly, for purposes of the present invention, as the vehicle  10  is being propelled over a power segment  20  in the roadway  18  by the LSM, the battery  16  can be recharged. Specifically, as the vehicle  10  moves along the roadway  18  under the influence of the LSM, the wheel  12  is rotated by its contact with the roadway  18 . This rotation of the wheel  12  is then used to generate an a.c. voltage with the motor/generator  30  (i.e. the motor/generator  30  is in its generator mode). The a.c. voltage is then converted to a d.c. voltage by the inverter-rectifier  32  for use in recharging the battery  16 . 
         [0025]    When the vehicle  10  is not traveling over a power segment  20 , and therefore can no longer establish an LSM with its magnet array  14 , the magnet array  14  is raised to its retracted configuration (see  FIG. 3A ). In this case, the vehicle  10  operates with an electric motor as its other propulsion unit. Specifically, with the motor/generator  30  now directed by the control system  40  to operate in the motor mode, electrical power from the battery  16  is passed through the inverter-rectifier  32  and to the motor/generator  30  to run the motor/generator  30  as a motor (i.e. the motor/generator  30  is in its motor mode). Thus, the motor/generator  30  functions as a propulsion unit to rotate the wheel  12  for propulsion of the vehicle  10 . 
         [0026]    While the particular Linear Motor Charged Electric Vehicle as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.