Abstract:
A plug-in hybrid vehicle drive system, including an internal combustion engine for driving one or more wheels of a vehicle, at least one on-wheel electrically powered motor, the motor coupled to a speed reduction mechanism, the speed reduction mechanism coupled to a vehicle wheel for driving at least one wheel of the vehicle, a battery located in the vehicle and connected to the at least one on-wheel motor for supplying power to the on-wheel motor, a battery charger including an AC/DC power converter, and an AC outlet connector in communication with the battery charger for receiving power from an external source.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of co-pending U.S. patent application Ser. No. 11/875,557, filed Oct. 19, 2007, which claims the benefit of, under 35 U.S.C. 119(e), U.S. Provisional Patent Application No. 60/919,038, filed Mar. 20, 2007, each of which are hereby incorporated herein by reference in their entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to hybrid drive vehicles generally and more particularly to plug-in hybrid vehicles. 
       BACKGROUND OF THE INVENTION 
       [0003]    Some hybrid drive vehicles, known as hybrid electric vehicles (“HEV”), incorporate an internal combustion engine as well as at least one electric motor and a bank of batteries. Contrary to all-electric vehicles, in these first generation hybrids the batteries are not charged from the utility grid but from a generator driven by the engine. The addition of the electric motor improves fuel economy by enabling the engine to run at its most economical speed at all times and to be shut down rather than idling when the car is stationary. In some hybrids both systems drive the wheels directly whereas in others, so called series hybrids, the engine drives only a generator, which powers the electric motor and/or charges the batteries. It is generally recognized that in a hybrid electric vehicle the rated electric power needs to be the same order of magnitude as the rated power of the combustion engine for best fuel economy. 
         [0004]    Various hybrid vehicle drive systems are known and some have been implemented in production vehicles. For example, U.S. Pat. No. 6,864,652 to Kubo et al. (“the Kubo patent”) discloses a drive system for an automotive vehicle including an internal combustion engine for driving the front wheels and an ancillary electric motor for driving the rear wheels. The vehicle is operable in both a front-wheel drive mode and a four-wheel drive mode. However, prior art systems such as the one disclosed in the Kubo patent require substantial modification and/or remanufacture of the vehicle power train to be implemented. 
         [0005]    U.S. Pat. No. 6,644,427 to Schulte (“the Schulte patent”) discloses a system for providing parallel power in a hybrid vehicle. The system includes a compact electric motor that is coupled to an input shaft of the vehicle&#39;s transmission. The Schulte patent describes the system as being adaptable for installation in a conventional vehicle to convert it to a parallel hybrid-electric vehicle. However, the process requires the machining of components to fit the particular vehicle and requires modifications to the primary drive system of the vehicle including its drive shaft and transmission. For example, the conversion process described in the Schulte patent requires removing the vehicle&#39;s transmission and driveshaft, replacing the transmission input shaft, and mounting a motor to the transmission that is machined to fit the particular transmission. 
         [0006]    There have been some prior attempts to employ in-wheel motors in vehicles. For example, U.S. Patent Application Publication No. 2007/0107959 to Suzuki et al. and U.S. Pat. No. 5,721,473 to DeVries disclose in-wheel motors. However, each of these prior art in-wheel motors includes a cylindrical stator circumscribing the wheel. This design is disadvantageous because it substantially reduces the space available for brakes and suspension components, and requires an entirely new custom wheel. A similar in-wheel motor is also disclosed in U.S. Pat. No. 5,438,228 to Couture et al. Each of these prior art in-wheel motors reduce the space provided for the vehicle&#39;s brakes and suspension components, and are not also adaptable for use on a vehicle&#39;s existing wheel. 
         [0007]    There have also been prior attempts to attach a direct drive motor to a wheel coupled with an electrical system that can induce a rotational force on the wheel. U.S. Pat. No. 7,658,251 to James (“the James patent”) discloses a direct drive traction vehicle motor system for a wheeled vehicle. The system includes an electric motor rotor attached to a vehicle wheel with an electric motor stator attached concentrically around the rotor. This system does not disclose or contemplate a motor coupled to a speed reduction mechanism. The drawbacks to a direct drive motor include, considerable addition to the unsprung mass of the vehicle wheel, which can cause un-desired changes in vehicle handling characteristics. Although simple in nature, a direct drive system becomes bulky and heavy in relation to their rated power and torque, because the rotational speed of the motor is limited by the rotational speed of the wheel. 
         [0008]    It is therefore desired to provide a geared hybrid vehicle drive system (indirect drive) that overcomes the drawbacks of the prior art. It is further desired to provide a hybrid vehicle drive system readily adaptable for implementation in existing non-hybrid vehicles. 
         [0009]    It is further desired to provide a hybrid vehicle indirect drive system including plug-in capability. In recent years a novel category of hybrids, so called plug-in hybrids (“PHEV”) have appeared, designed to be charged from the electric grid while stationary. Plug-in hybrids further improve economy and mileage because energy drawn from the grid is many times less expensive than the same amount of energy delivered by an internal combustion engine. Several major vehicle manufacturers are working towards commercializing plug-in hybrids however they are still several years away. Within the last two years, some PHEV has become available from aftermarket sources that generally comprise a conventional hybrid with added battery capacity and modified control systems and are able to operate in an all-electric mode for short durations. However, an improved hybrid vehicle system with plug-in capability is desired. 
       SUMMARY OF THE INVENTION 
       [0010]    The present invention is based on the fact that relatively little power is required to propel a light car at a steady rate in regular highway traffic. Many vehicles require only 10-15 horsepower or even less during maybe 80% of time on the road. In most cars the balance of available engine power is only required for acceleration and hill climbing. 
         [0011]    Accordingly, it is a principal objective of the invention to provide a geared electric drive-assist system to be added to conventional vehicles. For example, a system according to the invention may comprise electric motors each coupled to a speed reduction mechanism such as a gearbox, belt drive or roller chain in a step down configuration. The electric motor(s) is/are designed to bolt onto the vehicle, and the speed reduction mechanism connects the electric motor to the wheel so that the electric motor can impart a rotational force on the wheel. The electric motor can mount off center of the wheel. In one example, the speed reduction mechanism allows the use of a motor that rotates 3 to 4 times faster than the wheel. An indirect drive system provides several advantages over a direct drive system. The motor used can be considerably smaller for a given output power. A smaller motor brings along cost savings as well as weight savings. The weight savings coupled with an off center mounting location of the motor adds considerably less to the un-sprung mass in relation to a direct drive system dependent on the mounting location relative to the wheel center and the system attachment point. For example, if the motor is centered between the system attachment point and the wheel center, only 50% of the weight can be considered un-sprung mass. This advantage allows the indirect drive system to be installed with less impact on the vehicle handling characteristics. 
         [0012]    Attachment points for the system include the wheel flanges, bumper, wheel wells, vehicle frame and the rear axles. The system may require the replacement of original wheels or the system may be adapted to attach to wheels currently in use on the vehicle. The system can still utilize the original suspension, brakes and wheel bearings. An indirect drive system according to the invention also incorporates a bank of batteries and power management module located in the trunk or elsewhere in the vehicle. The system may also include plug in capabilities that include a battery charger and an AC plug which can charge the batteries using power from an external source. 
         [0013]    It is a further objective of the invention to provide an indirect electric drive system, which is sufficiently simple to be retrofitted to an existing vehicle by an auto repair shop or by a moderately mechanically proficient owner. A further objective of the invention is to propose inexpensive factory modifications to vehicles originally designed with only a combustion engine (e.g., gasoline or diesel), in order to facilitate addition of a drive system according to the invention. The indirect electric drive-assist system may be added by the factory during production, at purchase as a dealer option or at a later date whenever the owner may decide to do so. 
         [0014]    These and other objectives are achieved by providing a plug-in hybrid vehicle indirect drive system, comprising an internal combustion engine for driving one or more wheels of a vehicle. The system further includes at least one electrically powered motor and a speed reduction mechanism coupled to the electrically powered motor and one of the wheels of the vehicle. A battery is located in the vehicle and connected to the at least one electrically powered motor for supplying power to the electrically powered motor. The system further includes a battery charger, an AC/DC power converter, and an AC outlet connector in communication with the battery charger for receiving power from an external source. 
         [0015]    The speed reduction mechanism may include a gearbox, roller chain, belt drive or another equivalent transmission that provides a step down. 
         [0016]    The indirect drive system may be attached to the vehicle by a connection rod. The connection rod providing sufficient degrees of freedom to absorb the relative movement between the axle and the vehicle body. The connection rod may include a ball and socket joint on each end. The attachment point for the connection rod may be located on the vehicle frame, wheel well or fender. 
         [0017]    The electrically powered motor used in the indirect drive system may be mounted off center of the vehicle wheel. A conduit may be mounted to the vehicle with a power cable extending from a battery module to the electrically powered motor via the conduit. 
         [0018]    In some embodiments, the system includes an adapter plate connectable to the wheel of the vehicle using the lug nuts on the vehicle wheel. The adapter plate includes one or a plurality of drive holes for receiving drive pins. The drive pins extend from an integrated shaft in the speed reduction mechanism, and the drive pins couple to the adapter plate and allow the electrically powered motor to impart a rotational force on the vehicle wheel. 
         [0019]    The system may also include a driver operable controller in communication with the battery for controlling the power supplied to the at least one electrically powered motors. The vehicle can be adapted to be drivable by either or both of the internal combustion engine and the indirect electric drive system. The vehicle may further be fueled by diesel fuel. 
         [0020]    Other objects of the invention are achieved by providing an indirect drive system including at least one electrically powered motor, a housing, and a speed reduction mechanism within said housing and coupled to said electrically powered motor via a power input shaft. The system further includes a power output shaft connectable to a wheel of a vehicle and a connection rod having a first end attached to said housing and a second end attachable to the vehicle. The speed reduction mechanism comprises a first component, being one of a gear, a sprocket or a pulley, coupled to the power input shaft, and a second component, being one of a gear, a sprocket or a pulley, coupled to said power output shaft. The first component has a diameter less than a diameter of the second component. 
         [0021]    In some embodiments, the first component is an input gear and the second component is an output gear, wherein the speed reduction mechanism may further include at least one intermediate gear between the input gear and the output gear. In other embodiments, the first component is a first pulley and the second component is a second pulley, wherein the speed reduction mechanism further includes a belt extending around the first and second pulleys. In still other embodiments, the first component is a first sprocket and the second component is a second sprocket, wherein the speed reduction mechanism further includes a chain extending around the first and second sprockets. 
         [0022]    Further provided is a hybrid vehicle indirect drive system, including at least one electrically powered motor, a speed reduction mechanism coupled to the electrically powered motor and a wheel of a vehicle, the speed reduction mechanism including an output shaft having one or a plurality of drive pin holes, and a battery connected to the at least one electrically powered motor for supplying power to the electrically powered motor. The system further includes an adapter plate attachable to lug nuts on the wheel of the vehicle, the adapter plate including one or a plurality of drive pin holes. Drive pins are inserted into the drive pin holes on the output shaft and the drive pin holes in the adapter plate such that that the drive pins impart a rotational force on the vehicle wheel when power is supplied to the electrically powered motor. 
         [0023]    Also provided is a hybrid vehicle indirect drive system including at least one electrically powered motor, a speed reduction mechanism coupled to the electrically powered motor and a wheel of a vehicle, the speed reduction mechanism including a housing, and a battery connected to the at least one electrically powered motor for supplying power to the electrically powered motor. A connection rod attaches the housing of the speed reduction mechanism to the vehicle via an attachment point on the vehicle, the connection rod providing sufficient degrees of freedom to absorb relative movement between the wheel and the vehicle. 
         [0024]    In some embodiments, the connection rod includes ball and socket joints on each end, a first one of the ball and socket joints attaching to the attachment point on the vehicle, and a second one of the ball and socket joints attaching to the housing. 
         [0025]    Other objects of the present invention are achieved by providing an indirect drive system for a vehicle including an electric motor mounted to the vehicle outboard of the vehicle wheel, the electric motor attached to a vehicle wheel via a speed reduction mechanism, the speed reduction mechanism providing a step down gear ratio that allows the electric motor to rotate faster than the vehicle wheel, further a power cable connected to the stator for receiving electric power to the motor. 
         [0026]    Further provided is a hybrid vehicle system including an internal combustion engine for driving two or more wheels of a vehicle, at least one motor for driving at least one wheel of the vehicle, the motor including a speed reduction mechanism, wherein the geared output of the motor is mechanically attached to a vehicle wheel, at least one battery for supplying power to each of the at least one motor, a battery charger including an AC/DC power converter, and an AC outlet connector in communication with the battery charger for receiving power from an external source. 
         [0027]    A typical candidate for addition of an indirect drive-assist system according to the present invention is a light, small to mid-size vehicle with an internal combustion engine driving either the front wheels or the rear wheels. The indirect drive-assist system is installed on one or two axles and connected to a battery bank via a power management system located in the trunk or elsewhere in the car. The drive-assist system is largely independent of the original drive system, and control components enable the driver to operate the vehicle in engine mode or electric drive mode individually or together at will. Normally the car is started and brought up to cruising speed in engine mode, and then the gas pedal is released or the shift set to neutral, while engaging the drive-assist system. The on-wheel motors may then propel the car along a highway at a steady rate at zero or minimal fuel consumption. The engine can be re-engaged at any time and used together with or independently of the drive-assist system, but the system is designed to power the car on its own about 60-80% of the road time dependent on conditions and driver habits. It may also be able to perform low torque regenerative braking in either mode. 
         [0028]    Other objects, features and advantages according to the present invention will become apparent from the following detailed description of certain advantageous embodiments when read in conjunction with the accompanying drawings in which the same components are identified by the same reference numerals. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]      FIG. 1  is an exploded view of one embodiment of an indirect electric drive system. 
           [0030]      FIG. 2  is a cross section of the system show in  FIG. 1 . 
           [0031]      FIG. 3A  shows another embodiment of the indirect electric drive system. 
           [0032]      FIG. 3B  shows another embodiment of the indirect electric drive system. 
           [0033]      FIG. 4  shows a perspective view of indirect electric drive assist system according to the present invention installed on a vehicle wheel. 
           [0034]      FIG. 5  is a schematic representation of the components of the indirect drive system according to the present invention. 
           [0035]      FIG. 6  shows a rear portion of a vehicle outfitted with an indirect drive system according to an exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0036]      FIG. 1  is an exploded view of one embodiment of an indirect electric drive system according to one exemplary embodiment of the present invention. The exemplary embodiment is a belt driven design, however, as discussed in more detail below, the system may employ a number of other types of speed reduction mechanisms such as a V belt, roller chain, and sprockets or gears as well as other transmission elements all within the scope of the invention. 
         [0037]    The system shown in  FIG. 1  includes a motor  1 , such as a Switched Reluctance DC motor, comprising a housing  2  and a cover  3 . Other types of motors, such as an AC induction motor, a DC shunt motor, and a permanent magnet brushless DC motor may also be used. The housing  2  and cover  3  hold ball bearings  4  and  5 , respectively. A motor shaft  6  is supported by the bearings  4  and  5 . 
         [0038]    A laminated rotor  7  is mounted to shaft  6 . The motor  1  includes a stator  8  composed of stacked laminations with inwardly protruding poles, each pole being surrounded by a bobbin wound coil  9 . In some embodiments, the stator  8  is comprised of high mechanical integrity plastic or resin. The stator  8  and rotor  7  are located concentrically inside the motor housing  2 . 
         [0039]    While a concentric arrangement of the rotor  7  and stator  8  is shown, the rotor  7  and stator  8  may also be positioned axially adjacent to one another. For example, the stator may include wound coils arranged (e.g., in a “flower petals” configuration) on a side surface of the stator. A rotor of heavy sheet steel with an array of magnets is placed in close proximity to the side surface of the stator. Other embodiments of the present invention may include two or more stators and/or two or more permanent magnet rotors arranged coaxially for increased torque. 
         [0040]    As shown in  FIG. 1 , the selected motor  1  is bolted onto a housing  10  and a timing belt pulley  11  is mounted onto the shaft  6  of the motor  1 . A timing belt  12  connects pulley  11  and the driven timing belt pulley  13 , which is supported between ball bearings  14  and  15 . Bearing  14  is seated inside housing  10  and bearing  15  is seated inside hollow housing  20 . An integral shaft  22  (See  FIG. 2 ) of pulley  13  protrudes through the back plane of housing  20  and is drilled for drive pins  16  (See  FIG. 2 ). 
         [0041]    The pulley and belt configuration allows for a step down between the rpm of the shaft  6  and the wheel of the vehicle. For example, this exemplary embodiment may enable the use of a motor  1  which rotates for example 3 to 4 times faster than the wheel of the vehicle. In an alternative embodiment, the element  12  is a roller chain extending around two pulleys (e.g.,  11  and  13 ) or sprockets and achieves similar performance. 
         [0042]    The assembly connects to lug nuts  18  of vehicle&#39;s wheel by means of an adapter plate  17 . The lug nuts  18  connect the vehicle wheel to the vehicle. A central bolt  19  extends through pulley  13  and connects with the adapter plate  17  via a central thread, and one or more drive pins  16  (See  FIG. 2 ) engage a pattern of holes  21  in the adapter plate  17  securing a positive connection without slip. 
         [0043]      FIG. 2  shows a cross section of the system shown in  FIG. 1 . In  FIG. 2 , the integral shaft  22  of pulley  13  can be seen protruding through hollow housing  20 . One or more (e.g., three) drive pins  16  pass through the hole pattern  21  in adapter plate  17 . The system further includes a conduit  25 . Power is supplied to the motor  1  via a power cord  26  which passes into the vehicle through the conduit  25 . 
         [0044]      FIG. 3A  shows an alternative speed reduction mechanism to the belt drive shown in  FIGS. 1 and 2 . This embodiment is a gear system having a 1:3 step down ratio and an intermediate gear to bridge the distance between input and output gears. This step down ratio advantageously allows the use of a lighter and more compact motor than a direct drive version. The speed reduction mechanism shown in  FIG. 3A  may produce approximately 1,000 rpm by means of a motor  1  running at 3,000 rpm. 
         [0045]    As shown in  FIG. 3A , the system includes a housing  310  including an input gear  320 , and output gear  330 , and an intermediate gear  340 . An electric motor drive shaft  322  passes through a hole in housing  310 . The shaft  322  is connected to and receives power input from the motor  1 . The shaft  322  has a key  324 , which inhibits rotation of the input gear  320  relative to the shaft  322 . The input gear  320  meshes with the intermediate gear  340 , which is rotatable about a shaft  342 . The intermediate gear  340  meshes with the output gear  330 . Output gear  330  has an integrated shaft  332  include drive pin holes  334 . The shaft  332  is connectable to a wheel of a vehicle by means of an adapter plate  17  as shown in  FIGS. 1 and 2 . In particular, drive pins are inserted via the holes  334  to connect the shaft  332  to the adapter plate  17  as shown in  FIGS. 1 and 2 . 
         [0046]      FIG. 3B  shows another embodiment of the gear system having a two step reduction. In this embodiment, the input gear  320  is meshed with a first intermediate gear  340 . The first intermediate gear  340  is mounted on the shaft  342  with a second intermediate gear  344  which meshes with the output gear  330 . The first step down ratio between the gear  320  and gear  340  is 1:1.8. The second step down ratio between the gear  344  and the gear  330  is 1:3, giving a total step down ratio of 1:5.4. The speed reduction mechanism shown in  FIG. 3A  may produce approximately 1,000 rpm by means of a motor  1  running at 5,400 rpm. 
         [0047]      FIG. 4  shows a perspective view of indirect electric drive assist system according to the present invention installed on a vehicle  400 . A connecting rod  410  is attached to the vehicle  400  on a mounting block or clamp  420 , which is preferably located on the front rim of the fender  402  or other structurally rigid portion of the vehicle  400 . The connecting rod  410  has ball and socket joints  422  and  424  on each end. The joints  422 / 424  absorb relative movement due to differences in loading and bumpy travel without any friction due to sliding motion. The connecting rod  410  is attached to the housing  10  and the mounting block  420  with bolts  432  and  434 , respectively. 
         [0048]    Power is supplied to the motor  1  through a conduit  25 . The conduit  25  extends next to the wheel  440  of the vehicle  400  and into the wheel well for connection to a power system (e.g., located in the trunk of the vehicle  400 ). For example, the conduit  25  may extend through a rubber lined bushing attached to the body behind or above the wheel  440 . 
         [0049]      FIG. 5  shows a schematic of the indirect drive system according to the present invention. The cable  26  extends through the conduit  25  to a power management module  502  located in the trunk or elsewhere in the vehicle  400 . The system further includes a battery module  504  connected to the power management module  502 , a charger  506  (e.g., including a DC to AC power converter), and an AC outlet connector  508 . The battery module  504  may include, for example, a plurality of lead acid batteries or preferably lithium-ion batteries. 
         [0050]      FIG. 6  shows the rear portion of a vehicle  400  outfitted with an indirect drive system according to an exemplary embodiment of the present invention. The housing  10  and motor  1  are mounted external to the wheel  440 . The system may be implemented on one or both rear wheels of the vehicle  400 , and/or on either or both of the front wheels (not shown). As shown in  FIG. 6 , the motor  1  is located horizontally off center between the wheel  440  and the vehicle frame. While the system is shown mounted in a horizontal configuration, it may also be mounted vertically (e.g., extending upwards) to accommodate different vehicle types. However, in the vertical configuration, the entire weight of the motor, transmission, and housing is added to the unsprung weight, whereas in the preferred horizontal configuration only about half of the weight of the motor can be considered unsprung weight. 
         [0051]    As one of ordinary skill will understand from the preceding description, the present invention provides a novel system for supplementing power to a vehicle as an aftermarket or dealer installed add-on system, or as an original equipment option on the vehicle. The present invention may be implemented with minimal modification to the vehicle and minimal added weight. For example, some embodiments of the present invention employ the existing axles and wheels of the vehicle. By way of the present invention, any vehicle may be readily converted into a hybrid vehicle and preferably a plug-in hybrid vehicle. 
         [0052]    The indirect drive system of the present invention advantageously allows for use of a smaller motor than in prior art systems due the speed reduction mechanism. Thus, the motor can be designed considerably smaller for a given output power bringing along savings in cost and total weight over the direct drive system. The motor may also be mounted off-center from the wheel. The motor adds less to the un-sprung mass dependent on its location between the wheel center and the system attachment point. For example, if the motor is centered between the two points only 50% of its weight can be considered un-sprung mass. 
         [0053]    Although the invention has been described with reference to a particular arrangement of parts, features and the like, these are not intended to exhaust all possible arrangements or features, and indeed many modifications and variations will be ascertainable to those of skill in the art.