Abstract:
A motor drive system configuration for a vehicle. The motor drive system includes an engine operable for providing power to the vehicle, a motor operable for providing power to a first wheel and a second wheel of the vehicle. The motor drive system also includes a first transmission mounted between the engine and the motor and in operative engagement with the motor and the engine. The first transmission includes a first clutch for coupling and decoupling the motor with the engine. The motor drive system also includes a differential in operative engagement with the transmission and coupled to the first wheel and the second wheel, and a clutch for disabling the connection between the motor and the wheels.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of and priority to U.S. Provisional Application No. 61/220,048, filed Jun. 24, 2009, which is incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    The present disclosure relates generally to a motor drive system for a vehicle. More specifically, the present disclosure relates to a drive configuration for hybrid series and parallel high speed motor drive systems. 
       DESCRIPTION OF THE RELATED ART 
       [0003]    Hybrid electric vehicles (HEV) and full electric vehicles (FEV) use motors to convert electrical energy into kinetic energy. Whereas HEVs combine an internal combustion engine and one or more electric motors, FEVs use electrical motors exclusively. The motors are typically part of a powertrain that generate power to drive a vehicle and the vehicle&#39;s motor drive system. There are a number of powertrain configurations including series hybrid and parallel hybrid. A series hybrid configuration uses electric drives powered by an internal combustion engine. The combustion engine drives an electric generator instead of directly driving the wheels. The engine of a series hybrid configuration may be useful for charging a battery, charging a capacitor, directly powering the electric motor, etc. In a parallel hybrid configuration, the electric motor(s) and the internal combustion engine are installed so that they can power the vehicle together or independently. The internal combustion engine, the electric motor and the gear box may be coupled by automatically controlled clutches. While the vehicle is operating in the electric mode, the clutch between the internal combustion engine is open while the clutch to the gear box is engaged. While the vehicle is operating in the combustion mode, the engine and motor run at the same speed or gear ratio dependent proportional speeds. 
         [0004]    Conventional series hybrid and parallel hybrid configurations may suffer from efficiency losses under certain operating conditions because losses are sustained in both the generator and the motor. These losses in efficiency stem from resistance in the motor windings, switching in the inverter, etc. and may occur under various operating conditions, such as, highway cruising conditions where the impact is noted most severely. In addition, a four wheel drive series requires three electric machines if the front and back axles cannot be linked mechanically (one on the front axle, one on the rear axle, and one mounted on the engine acting as a generator). Moreover, conventional series hybrid and parallel hybrid configurations that are modifications of conventional architectures include electric machines that operate at speeds that increase costs. 
         [0005]    Thus, there is a need in the art for a drive configuration for a motor drive system that is more efficient and cost effective and that enhances vehicle performance. 
       SUMMARY 
       [0006]    Accordingly, the present disclosure relates to a motor drive system configuration for a vehicle. The motor drive system includes an engine operable for providing power to the vehicle, a motor operable for providing power to a first wheel and a second wheel of the vehicle. The motor drive system also includes a first transmission mounted between the engine and the motor and in operative engagement with the motor and the engine. The first transmission includes a first clutch for coupling and decoupling the motor with the engine. The motor drive system also includes a differential in operative engagement with the transmission and coupled to the first wheel and the second wheel. 
         [0007]    An advantage of the present disclosure is that the drive configuration/arrangement promotes higher efficiency in terms of operation and performance. A further advantage of the present disclosure is that it reduces the number of electric machines needed when compared to a series hybrid electric all wheel drive (eAWD). Still a further advantage of the present disclosure is that it allows for mechanical power transfer from the engine to the wheels to improve efficiency. Still a further advantage of the present disclosure is that the drive configuration enables a compact package having low complexity and reduced costs. 
         [0008]    Other features and advantages of the present disclosure will be readily appreciated, as the same becomes better understood after reading the subsequent description taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a perspective view of a vehicle, according to an exemplary embodiment. 
           [0010]    FIG,  2  is a schematic view of a motor drive system configuration for the vehicle of  FIG. 1 , according to an exemplary embodiment. 
           [0011]      FIG. 3  is schematic view of a motor drive system configuration, according to another embodiment. 
           [0012]      FIG. 4  is a chart detailing various operating modes for the vehicle of  FIG. 1  and corresponding operation of the motor drive system components, according to an exemplary embodiment. 
           [0013]      FIG. 5  is a top view of a vehicle and powertrain architecture having a motor drive system, according to an exemplary embodiment. 
       
    
    
     DESCRIPTION 
       [0014]    Referring generally to the Figures and particularly to FIG. I, a vehicle  10  is illustrated. In this example the vehicle  10  is a plug-in hybrid electric vehicle (HEV) that is gasoline and electric powered. The vehicle  10  may be a passenger car, truck, or other type of vehicle having a battery. In another example, the vehicle  10  is a dedicated battery powered vehicle. In still another example, the vehicle  10  is a full electric vehicle (FEV). The engine may operate on another fuel, such as, diesel, methane, propane, hydrogen, or the like. 
         [0015]    Referring now to  FIG. 2 , a motor drive system configuration  12  and arrangement for vehicles, such as, HEVs, or the like, are shown. The motor drive system includes various components coupled together in operative engagement, such as, an engine  14 , a motor  16 , a first transmission (gearbox)  18   a,  a second transmission  18   b,  a differential  22 , a first clutch  24   a,  a second clutch  24   b,  a first wheel  26 , and a second wheel  28 . The motor drive system  12  also includes one or more axles, shafts, or the like; operatively interconnecting the various components of the motor drive system  12 . The motor drive system can also include other components that are conventionally known or associated with a powertrain or motor drive system. Various types of engines are contemplated, such as, a four-cylinder gasoline powered engine, or the like. The selection of an engine is dependent on various factors, such as, vehicle size, weight, battery capacity, or the like. The motor  16  can be an electric machine, such as, a high speed electric motor. Example of a electric motors include 12v high speed electric motor, DC series wound electric motor, permanent magnet DC electric motor, phase AC induction motor, or the like. The first and second transmissions  18   a,    18   b  can be one of a single-speed transmission, a two-speed transmission, a multispeed transmission, a single-speed transmission using a planetary gear reduction, or the like. The motor drive system  12  of the present disclosure uses modifications to current standard parts to minimize design requirements and/or use unique arrangements with configurations that minimize the packaging volume. The greater freedom to select motors independent of motor speed allows for a better motor match for a given type of vehicle which improves vehicle efficiency. 
         [0016]    The motor drive system  12  is configured in a lateral arrangement relatively to the width of the vehicle  10 . The motor  16  is connected to the engine  14  via a motor shaft that extends through the first transmission  18  and into the engine  14 . The engine  14  is connected to the first transmission  18   a  and is coupled and decoupled from the first transmission  18   a  via the first clutch  24   a.  It should be noted that the first clutch  24   a  can be positioned in alternative manners, such as, on either side of the first transmission  18   a,  internal or within the first transmission  18   a,  or the like. 
         [0017]    The motor  16  is operatively connected to the first transmission  18   a  and to the second transmission  18   b.  The second transmission  18   b  is operatively connected to the differential  22  such as, by a second clutch  24   b.  The differential  22  is operatively connected to a first wheel  26  and a second wheel  28  by a shaft, or the like. It should be noted that the second clutch  24   b  can also be positioned in alternative manners, such as, on either side of the second transmission  18   b,  internal or within the second transmission  18   b,  or the like. 
         [0018]    The transmissions  18   a,    18   b  can be de-coupled from the engine, motor, differential, or the like, by opening or closing the clutches  24   a,    24   b  or by shifting the vehicle  10  into neutral. The first and second transmission  18   a,    18   b  are positioned between the engine  14  and the motor  16  and enables the motor  16  to spin at any speed in relation to the speed of the engine  14  and thereby increases the efficiency and performance of the vehicle  10 . Moreover, positioning the transmissions  18   a,    18   b  between the engine  14  and the motor  16  enables the motor  16  to be operated at a speed range unhindered by engine speed limitations, thereby allowing for a lower cost motor  16 . The motor  16  (via the motor shaft) is operatively connected to the differential  22  by shafts and gears. The differential  22  is coupled to front wheels  26 ,  28  via output shafts. This allows for various vehicle operating modes if the drive is coupled with another motor on the rear axle. if a separate drive motor is added to the wheels, the vehicle operating modes include an EV 4WD mode, a HEV 4WD mode, and a Series 2WD mode. 
         [0019]    The motor drive system configuration  12  of the present disclosure includes a mechanical link between the engine  14  and the wheels  26 ,  28  to thereby minimize or eliminate efficiency losses in the generator and/or motor  16 . Furthermore, one electric machine is used as a generator and is mounted on the engine  14 . This enables the reduction of the number of electric machines needed or used and enables the electric machines to operate at speeds that allow for minimal costs. For example, large, slow motors need larger generators (that require more magnetic material) for a given amount of power as compared to a higher speed motor. The motor drive system configuration  12  of the present disclosure also enables the use of high speed motors and thereby reduces driveline costs. 
         [0020]    In the EV 4WD mode, the clutch  24   a  between the engine  14  and the motor  16  is open. The motor  16  drives the front wheels  26 ,  28  using battery power and the rear wheels are driven by another motor. 
         [0021]    In the HEV 4WD mode, the motor  16  provides power at launch and low speeds. At higher speeds, the engine  14  also provides power. At cruising speed, the engine  14  will provide most or all of the power directly to the front wheels  26 ,  28 , avoiding losses through the two electric machines. If the front wheels  26 ,  28  start to slip or if power needs to be provided to all wheels, the rear motor will power the rear wheels. 
         [0022]    In the Series 2WD mode, the clutch  24   c  between the motor  16  and the engine  14  is closed. The clutch  24   a,    24   b  between the motor  16  and wheels  26 ,  28  is open. The engine  14  provides power to the motor  16 . The motor  16  (powered by the engine) provides the electrical power to the rear drive. 
         [0023]    Referring now to  FIG. 3 , a schematic of an alternate motor drive system configuration  212  is shown. In this embodiment, the motor drive system  212  is configured in a longitudinal arrangement relatively to the length of the vehicle  10 . The engine  214  is connected to a first wheel  226  by a differential  222  and to a second wheel  228 . The engine  214  is also connected to a first transmission  218   a  (alternatively, the first transmission  218   a  can be a single-speed planetary gear reduction, or the like) via a first clutch  224   a.  It should be noted that the first clutch  224   a  can be positioned in alternative manners, such as, on either side of the first transmission  218   a,  internal or within the first transmission  218   a,  or the like. The first transmission  218   a  is operatively connected to a motor  216 . The motor  216  is operatively connected to a second transmission  218   b  via a second clutch  224   b.  The second transmission  218   b  is operatively connected to the differential  222  via a gear  230  (such as, a pinion gear, planetary gear set, or the like). It should be noted that the second clutch  224   b  can be positioned in alternative manners, such as, on either side of the second transmission  218   b,  internal or within the second transmission  218   b,  or the like. 
         [0024]    Referring now to  FIG. 4 , a chart detailing various examples of operating modes of the motor drive systems of  FIGS. 2 and 3  is shown, although others are contemplated. While the vehicle is operating in a particular mode, components of the drive system, such as, the engine, the first clutch, the first transmission or gearbox, the motor, the second transmission or gearbox, and the second clutch perform a function. 
         [0025]    In operating mode one shown at  250 , the motor is starting the engine. In this mode, the engine is cranking, the first clutch is closed, the first transmission is in gear, the motor provides power, the second transmission is not in use, and the second clutch is open. 
         [0026]    In operating mode two shown at  255 , the engine and/or the motor are driving the wheels of the vehicle. In this mode, the engine is powering, the first clutch is closed, the first transmission is in gear, the motor provides power, the second transmission is in gear, and the second clutch is closed. 
         [0027]    In operating mode three shown at  260 , the engine is driving the motor (acting as a generator) and the vehicle wheels are decoupled. In this mode, the engine is powering the vehicle, the first clutch is closed, the first transmission is in gear, the motor is generating electricity, the second transmission is not in use, and the second clutch is open. In order to drive the vehicle  10 , a second motor must exist, such as, at the rear of the vehicle  10 , or the like. 
         [0028]    In operating mode four shown at  265 , the motor is driving the vehicle wheels (EV operation). In this mode, the engine is not in use, the first clutch is open, the first transmission is not in use, the motor provides power, the second transmission is in gear, and the second clutch is closed. 
         [0029]    In operating mode five shown at  270 , the motor is taking power from the vehicle wheels and the vehicle is undergoing regenerative braking. In this mode, the engine is not in use (but maybe at idle or off), the first clutch is open, the first transmission is not in use, the motor is generating, the second transmission is in gear, and the second clutch is closed. 
         [0030]    Referring now to  FIG. 5 , a vehicle  310  with a powertrain architecture  311  having a motor drive system  12  is shown. The vehicle  310  includes a powertrain  311  that controls the operation of the vehicle  310 . The powertrain  311  can include various components, such as, engines, transmissions or gear boxes, drive shafts, differentials, electric motors, wheels, or the like, as previously described. The vehicle  310  may also include a gasoline powered engine that supplements one or more electric motors when required under certain operating conditions. The electrical energy is stored in an energy storage device, such as the battery  313 . The battery  313  may be a single unit, or a plurality of modules arranged in a predetermined manner, such as in series. Various types of batteries may be used, such as lead acid, or lithium-ion or the like. The battery is contained within a battery case and coupled to the vehicle&#39;s frame. The vehicle  310  also includes a motor drive system  312 . 
         [0031]    The motor drive system  312  is located at the front of the vehicle and can have various configurations, such as, the motor drive system configurations of  FIGS. 2-3 . The powertrain  311  can also includes a motor drive system  314  at the rear of the vehicle  310 . In this embodiment, the vehicle  310  includes a series hybrid high speed motor drive system  312  configuration, as shown in  FIG. 2 . The motor drive system  312  includes a motor driven generator. The motor drives the rear vehicle wheels through a single or multispeed transmission. The rear wheels can be or have motors with or without a reduction. Any one or combination of the motor drive system configurations of the present disclosure may be used in any type of vehicle, such as, an HEV, or the like, and with any type of powertrain architecture, such as, a series rear wheel drive (Series RWD), a series all wheel drive (Series AWD), an all wheel drive parallel (AWD Parallel), or the like. 
         [0032]    The foregoing designs shown and discussed may be modified with additional gears, ratios, speeds and/or incorporated with other solutions, components, or the like. They may also be mounted in any configuration and coupled together using any known techniques. 
         [0033]    Many modifications and variations of the present disclosure are possible in light of the above teachings. Therefore, within the scope of the appended claim, the present disclosure may be practiced other than as specifically described.