Abstract:
A highly energy efficient automobile that provides payload, safety and performance capacities similar to a comparable vehicle of a given vehicle class. The current invention is ideal for short to medium range urban and suburban driving. The current invention incorporates components in a unique and novel way, in which these components combine to form a system that produces an automobile that reduces overall air pollution while encouraging the commercialization of alternative energy sources. The current invention features an lightweight, low rolling resistance, digitally controlled and direct-drive electric propulsion system. A lightweight spaceframe with a suspension system provides a structure for mounting a low-aerodynamic-drag body system and other components. An intelligent power and thermal management system coupled with a removable auxiliary power module supplies the electrical energy required. While the preferred embodiment is substantially a passenger vehicle, the current invention may be scaled to other land vehicles.

Description:
CROSS-REFERENCE 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 11/953,787, filed on Dec. 10, 2007, which is incorporated herein by reference in its entirety and to which application we claim priority under 35 U.S.C. §120. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to automobiles and, more particularly, to hybrid electric vehicles. 
       BACKGROUND OF THE INVENTION 
       [0003]    Ever since automobiles were invented, there has been a need for a more energy efficient vehicle. A solution satisfying urban and suburban family transportation needs in a safe and fuel-efficient manner is desired by many for longer and more affordable commutes. In the past few decades, many scientific studies let to the belief that the increased used of automobiles worldwide is contributing to a global climate change phenomenon known as global warming, which is threatening the existence of many biological species and the current way of life of the populations in many countries. It is further believed that substituting fossil fuel uses with renewable or otherwise less polluting energy sources may result less drastic global warming effect. To further complicate the issue, the general population, substantially more so in the United States, tends to prefer larger vehicles. The demand for larger vehicles is satisfied essentially by truck-based vehicle platforms converted into passenger vehicles officially classified as light trucks. Truck platforms (or body-over-frame designs) tend to be heavy compared to regular passenger vehicles. And, the heavier the vehicle, the more energy is required to propel it over a given distance. The sharp increase in fuel consumption by light trucks collectively has been blamed for air pollution in major cities. 
         [0004]    Obviously, there are many conventional fossil-fuel driven passenger cars (automobiles), light trucks and crossover vehicles. Vehicles are generally classified based on their sizes, weights and payload capacities. Larger light trucks, including Sports Utility Vehicles (SUV) and pickup trucks are often used as passenger vehicles and offer great versatility in terms of passenger and cargo carrying capacities. Crossover vehicles are defined as a car based platform with a light-truck appearance. Some of these vehicles are designed or retrofitted with a hybrid electric drivetrain to improve fuel economy. Examples of prior art electric cars, hybrid electric passenger cars, hybrid electric SUVs and hybrid electric crossovers are 2001-2007 Toyota Prius, 2005-2007 Toyota Highlander hybrid, 2007 Ford Escape Hybrid, 2008 Chevy Tahoe “Two-mode” Hybrid, 2008 GMC Yukon, 1997 General Motors EV1, AC Propulsion eBox and T-zero. 
         [0005]    Some light trucks are outfitted with mechanical four-wheel-drive (4WD) or all-wheel-drive (AWD) transmissions and differentials to improve handling when driving in slippery road conditions. Examples are 2007 Audi Q7, 2007 Volkswagen Touareg and 2007 Toyota 4-Runner. These additional drive components adds significant amount of weight to the vehicles. Operating and maintaining a light truck is generally more expensive compared to smaller passenger vehicles due to higher fuel consumption and wear and tear on drivetrain parts because of the added weight. As a matter of fact, most of the off-road-capable vehicles sold in the United States are never taken off-road and yet they carry the extra weights of the heavy duty components, which severely impact their fuel efficiency compared to other lighter vehicle types of the same size. Therefore, it would be advantageous to incorporate a four-wheel-drive response without the transmission or differential parts. 
         [0006]    Not realizing the benefits of the modularity and flexibility that an electric coupling can offer, many inventors resort to mechanical solutions in which the power sources and the drive wheels are joined by mechanical couplings, or incremental improvements on the transmission parts. Such designs are described in U.S. Pat. Nos. 5,558,589, 5,931,757, 6,090,005 for A TWO-MODE, COMPOUND-SPLIT, HYBRID TRANSMISSION, 6,360,834 for a HYBRID ELECTRIC VEHICLE, 6,579,201 for an ELECTRIC HYBRID FOUR-WHEEL DRIVE VEHICLE, 5,343,970 for a HYBRID ELECTRIC VEHICLE, 7,237,634 for HYBRID VEHICLES, 6,840,341 for PARALLEL HYBRID VEHICLE, 6,945,345 for HYBRID ELECTRIC VEHICLE HAVING ALTERNATE POWER SOURCES, 6,656,083 for a HYBRID DRIVE SYSTEM, 6,811,508 for a HYBRID TRANSMISSION, PARTICULARLY FOR MOTOR VEHICLES, 6,852,053 for a DRIVETRAIN FOR A VEHICLE, 7,261,661 for a PARALLEL HYBRID TRANSMISSION HAVING A SINGLE MOTOR/GENERATOR, 7,220,199 for an INFINITELY VARIABLE POWER BRANCHING TRANSMISSION WITH TWO OPERATING MODES, 7,210,546 for a CONTROLLER AND CONTROL METHOD FOR A HYBRID ELECTRIC VEHICLE POWERTRAIN, 7,017,693 for a DRIVE DEVICE FOR HYBRID VEHICLE and 6,936,991 for METHOD AND APPARATUS FOR MOTOR CONTROL. 
         [0007]    Prior arts hybrid electric vehicles are typically smaller in size, mechanically complex and expensive to buy and maintain. They sometimes even the fuel savings of the entire lifetime of the vehicle cannot justify for the extra costs. Prior art electric vehicles, similar to the one described in U.S. Pat. No. 5,212,431 for ELECTRIC VEHICLE, produce no emission on board but typically have limited passenger and cargo capacity or operational radius. The process of generating electricity on the power grid involves burning fossil fuel and, based on the current energy mix, the emission could be higher than some other alternative methods of generating electricity onboard. Due to the limitation in current battery technologies, electric vehicles are typically small, underpowered, expensive, and thus, according to General Motors Corporation, impractical to be deployed in a large scale. Prior art hybrid electric vehicles, conventional passenger cars and conventional light trucks alike lack the ability to adapt to other fuel sources. This creates a barrier to entry for alternative fuel businesses because the cost to retrofit a vehicle to use another fuel source is generally cost-prohibitive. Therefore, a solution that offers the owner of the vehicle the liberty to choose between multiple fuel sources is highly desirable. 
         [0008]    Another problem is that while many consumers prefer larger vehicles because of the perceived safety of these larger vehicles, the reality is that most light trucks are built using existing commercial truck platforms. Higher centers of gravity and uneven weight distributions of a light truck also affect the vehicle&#39;s stability, which further increases the chance of a collision. Their body-over-frame designs also lack the sophisticated “crumble zones” commonly found in smaller passenger vehicles and make the occupants more susceptible to injuries during a crash. A modular design allows the designer to free up the space in front of the vehicle for more freedom in crumble zone design. Therefore, a solution that employs modular components, which allows designers to relocate components to meet the desired weight distribution and as a prerequisite to create improved crumble zone structures, is highly desirable. 
         [0009]    It is therefore an object of the invention to improve energy efficiency compared to a similar prior art in the same vehicle class, which is typically measured by the amount of energy consumed over the distance traveled. 
         [0010]    It is another object of the invention to meet the performance, safety and payload capacities of a similar prior art in the same vehicle class. 
         [0011]    It is another object of the invention to provide an all-wheel-drive propulsion system to improve traction. 
         [0012]    It is another object of the invention to reduce operational and maintenance costs compared to a similar prior art in the same vehicle class. 
         [0013]    It is another object of the invention to sustain a longer service life compared to a similar prior art in the same vehicle class. 
         [0014]    It is another object of the invention to operate on more than one energy source to increase demand for alternative energy sources. 
         [0015]    It is another object of the invention to provide an electric propulsion system that is capable to operate entirely on electricity. 
         [0016]    It is another object of the invention to enable economical aftermarket exchanges of onboard power plants. 
       SUMMARY OF THE INVENTION 
       [0017]    In accordance with the present invention, there is provided a highly energy efficient hybrid electric vehicle that provides payload, safety and performance capacities comparable to a conventional vehicle of a given vehicle class. The current invention is a novel automobile that sustains highly energy efficient operation while satisfying urban and suburban driving needs. In the past few decades, many scientific studies let to the belief that the increased used of automobiles worldwide is contributing to a global climate change phenomenon known as global warming, which is threatening the existence of many biological species and the current way of life of the populations in many countries. It is further believed that substituting fossil fuel uses with renewable or otherwise less polluting energy sources may result less drastic global warming effect. The current invention is unique in that its basic electric propulsion system has the ability to adapt to different energy sources by changing a removable component simply and economically. The current invention, with the ability to adapt to different fuel sources, creates an increased demand for alternative fuels and renewable energy despite the uncertainty in government positions and high barrier to entry in the energy market. The current invention is scalable and applicable to all classes of vehicles, with arbitrary number of wheel axles. Typically, the lighter a vehicle, the more energy efficient it becomes. In a preferred embodiment, the majority of the chassis and the body of the current invention are made with lightweight materials. A direct-drive electric propulsion system eliminates the need for heavy transmission parts and drive shafts. Thus, combined with regenerative braking and other feature described in this disclosure, the current invention is generally more energy efficient and requires less maintenance than prior art gasoline or diesel vehicles of the same vehicle class, and superior to prior art hybrid electric vehicles or electric vehicles in terms of modularity, capacities, performance and the ability to use multiple fuel sources. 
         [0018]    The current invention is a hybrid electric vehicle comprising a spaceframe, a body system, a suspension system, a propulsion system, a vehicle control system, a primary electrical system, a thermal management system and an auxiliary power module. A preferred embodiment described in this disclosure is a ground vehicle with two drive axles, two wheels on each axle, four doors and a rear hatch. The size and shape of the vehicle is substantially a light truck in the sports utility vehicle (SUV) category—comparable to a 2007 Toyota Highlander. The preferred embodiment is thus a so-called 4-by-4 or a four wheel drive (4WD) configuration. 
       INCORPORATION BY REFERENCE 
       [0019]    All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which: 
           [0021]      FIG. 1  is a front left perspective view of the current invention in its entirety; 
           [0022]      FIG. 2  is a left perspective view of the current invention in its entirety; 
           [0023]      FIG. 3  is a front left perspective view of a propulsion system with primary electrical system components; 
           [0024]      FIG. 4  is a block diagram view of a vehicle control system; 
           [0025]      FIG. 5  is a block diagram view of a primary electrical system; 
           [0026]      FIG. 6  is a block diagram view of a vehicle control bus; 
           [0027]      FIG. 7  is a block diagram view of a vehicle management bus; 
           [0028]      FIG. 8  is a left sectional view of a body system front section; 
           [0029]      FIG. 9  is a block diagram view of an electric parking brake system; and 
           [0030]      FIG. 10  is a left view of a spaceframe. 
       
    
    
       [0031]    For purposes of clarity and brevity, like elements and components will bear the same designations and numbering throughout the Figures. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0032]    The current invention is a hybrid electric vehicle comprising a spaceframe  32 , a body system  10 , a suspension system, a propulsion system  96 , a vehicle control system  138 , a primary electrical system, a thermal management system  28  and an auxiliary power module  30 . A preferred embodiment described in this disclosure is a ground vehicle with two drive axles, two drive wheels on each axle, four doors  100  and a rear hatch  98 . The size and shape of the vehicle is substantially a light truck in the sports utility vehicle (SUV) category—comparable to a 2007 Toyota Highlander. 
         [0033]    Body Structure. 
         [0034]    The main purpose of a spaceframe  32  is to provide structural support and mounting points for most of the other components on the preferred embodiment. Another purpose of the spaceframe  32  is to support the proper functioning of the suspension. Another purpose of the spaceframe  32  is to protect the occupants during a crash in any direction or a roof-crush incidence. Another purpose of the spaceframe  32  is to provide an exterior by which the overall styling and the aerodynamic properties are determined. Another purpose of the spaceframe  32  is to provide ingress and egress to and from the cabin compartment  112 . 
         [0035]    In a preferred embodiment, referring now to  FIG. 10 , the spaceframe  32  comprises a passenger cabin compartment  112  frame structure formed by rigid shell, a plurality of door frame structures, a plurality of rear hatch  98  frame structures, a front crumble zone  110 , a rear crumble zone  122 , front bumper  58 , rear bumper and an undercarriage  116  for said cabin compartment  112 . The spaceframe  32  defines the boundaries of various compartments within the vehicle and hence the space available for each. Hence, the design of the spaceframe  32  is typically application specific. The design of the spaceframe  32  not only affects aerodynamics but also human perceptions to the vehicle. 
         [0036]    As a frame typically contributes to about 25% of a prior art vehicle by weight, the material selected for the spaceframe  32  is critical to the overall energy efficiency of the system. In a preferred embodiment, said passenger cabin compartment  112  frame structure, said door frame structures and said hatch  98  frame structure are created substantially using lightweight and low-cost polymer composite materials such as polycarbonate-Polyethylene Terephthalate (PET)-fiberglass composite materials with approximately 10% to 30% glass fill that provide the desired interior and exterior dimensions with a lighter overall weight than a conventional aluminum or steel prior art. The spaceframe  32  may be reinforced with metals to increase strength or durability at certain locations of the spaceframe  32 . The spaceframe  32  provides the rigidity to resist collapse during a collision or a roof-crush incidence, and to support the proper functioning of the suspension. The front crumble zone  110  is a longitudinally mounted aluminum honeycomb structure. The rear crumble zone  122  may be made from the same longitudinally mounted aluminum honeycomb structure or simply an extension of the composite spaceframe  32 . 
         [0037]    Said aluminum honeycomb front crumble zone  110  and/or rear crumble zone  122  may be made from other metals or organic materials such as polycarbonate. The choice of material is a trade-off between the crush strength of the honeycomb structure, the amount of distance for crumbling, the deceleration (g-force) tolerable by the occupants and the regulations, and costs. 
         [0038]    In a preferred embodiment, the spaceframe  32  is created using a thermoplastic and fiberglass blend; hence, the spaceframe  32  may be manufactured economically using injection molding techniques. The spaceframe  32  may be partitioned into three segments: left frame and right frame and connecting structures in between. The parts are later on glued, bolted or welded together to form the desired shape. The door frames and the rear hatch  98  frame are manufactured using similar techniques. The advantages of thermoplastics include being inexpensive, recyclable and rust-free. 
         [0039]    The spaceframe  32  may also be fabricated using convention materials, such as aluminum and steel, and processes. 
         [0040]    Body. 
         [0041]    Referring now to  FIG. 1  and  FIG. 2 , The body system  10  is the exterior of the vehicle, which comprises a plurality of body panels  94 , a front windshield  12 , a plurality of windows  14 , a plurality of lighting elements  90 , a plurality of wipers, a plurality of body controls  92 , an upper front air diffuser  50 , a lower front air diffuser  52 , a plurality of side air diffusers  106 , a lower rear air diffuser  54  and other accessories typically found in prior art vehicles. Said plurality of body panels  94  further comprises a roof panel, door panels, a plurality of quarter panels, a front bumper cover  56 , a rear bumper cover  108  and a hood. The body system  10 , in a preferred embodiment, is mounted over the spaceframe  32  such that the spaceframe  32  itself is not exposed. 
         [0042]    The main purpose of the body system  10  is for isolating the interior and internal components from the elements. Another purpose of the body system  10  is to diffuse air flow efficiently when the current invention is in motion. Another purpose of the body system  10  is for, through the use of lightweight materials, reducing the weight and lowering the center of gravity of the vehicle, and thus improves energy efficiency and handling. 
         [0043]    In a preferred embodiment, a body panel is made from a honeycomb structure, perpendicular to the vehicle surface, sandwiched between two sheets of polyurethane-fiberglass composite. The honeycomb body panels  94  provide exceptional strength-to-weight ratios. Other materials, such as metals, may be used to reinforce the composite materials to increase the structure&#39;s stiffness and thermal stability. Another implementation of the spaceframe  32  is a body-over-frame design, which is commonly used on trucks and heavy-duty vehicles. Body-over-frame is commonly used when a single chassis (spaceframe  32 , suspension and propulsion system  96 ) is combined with different vehicle bodies to produce multiple functional variants. 
         [0044]    The main purpose of the roof panel is to protect the occupants of the vehicle during a crash or a roof-crush incidence. The roof panel may be created using the same material as the body panel or a heat-formed polycarbonate sheet to give a transparent or semi-transparent appearance. A more specific purpose of a roof panel in a preferred embodiment is to collect solar energy and converts it into electrical energy for the electrical systems. To achieve this, photovoltaic cells  136  are organized and attached to either the upper or lower surface of the roof panel. Coupled with a voltage regulator, the cells are wired into the electrical system. 
         [0045]    The main purpose of the plurality of body panels  94  is to create an aerodynamically efficient geometry in the front of the current invention to reduce aerodynamic drag during operation. The hood forms part of said upper front air diffuser  50 . Another purpose of the plurality of body panels  94  in a preferred embodiment is to collect solar energy and converts it into electrical energy for the electrical systems. To achieve this, photovoltaic cells  136  are bonded to the upper surface of the hood. Coupled with a voltage regulator, the cells are wired into the electrical system. 
         [0046]    The main purpose of the front lower air diffuser and the front upper air diffuser is to create an aerodynamically efficient geometry in the front of the current invention to reduce aerodynamic drag during operation. Another purpose of the front lower air diffuser and the front upper air diffuser is for funneling cool air into the heat exchangers  104  of the thermal management system  28 . The heat exchangers  104  may be mounted and hidden under the decorative diffuser covers  128  as show in  FIG. 8 . 
         [0047]    The main purpose of the side air diffusers  106  is to create an aerodynamically efficient geometry in the front of the current invention to reduce aerodynamic drag during operation. Another purpose of the side air diffusers  106  is to support climate control  102  of the interior. Another purpose of the side air diffusers  106  is for funneling cool air into the auxiliary power module  30  to support, if applicable, internal combustion and cooling. To achieve this, air ducts are constructed behind the body panels  94  to redirect the incoming air to the air intake of the auxiliary power module  30 , which is located in the mid-section of the current invention. 
         [0048]    The main purpose of said body controls  92  is for detecting and controlling said body components, said windows  14  and said lighting elements  90 . The body controls  92  comprise mechanical sensors for the doors  100 , the rear hatch  98  and the windows  14 , mechanical actuators for actuating the windows  14 , locking and unlocking the doors  100 , releasing the rear hatch  98  and activating the wipers and washers, switching the external lighting elements  90 . Body components in question further comprise door catches, door locks. Said lighting elements  90  further comprise a plurality of headlamp assemblies, a plurality of rear lamp assemblies, a plurality of turn signal markers, a plurality of license plate lights and a plurality of interior lighting elements  90 . 
         [0049]    Suspension System. 
         [0050]    The main purpose of the suspension system is to maintain traction between the tires and the road surface on which the vehicle is traveling. The suspension system is capable to support steering, acceleration and deceleration characteristics of the vehicle. The preferred embodiment of the current invention is very similar to some suspension systems found on conventional automobiles. In a preferred embodiment of the current invention, the suspension system comprises a front suspension  118  subframe, a rear suspension  120  subframe, a plurality of drive wheels on each subframe, anti-lock enabled hydraulic brake  124  system, electric parking brake  134  and the electric-assist steering column  82 . In a preferred embodiment, the front suspension  118  will be a plurality of McPherson-type suspension assemblies and the rear suspension  120  will be a plurality of double-A arm suspension assemblies. In order to further reduce rolling resistance, hence increases energy efficiency, low-profile, high-pressure tires are utilized. The front suspension  118  subframe is further comprising a metal frame for mounting the suspension parts and for attaching the subframe to the spaceframe  32 , a plurality of shock absorbers, a plurality of dampers, a plurality of wheel hubs, a plurality of constant velocity joints, a plurality of brakes and supporting components, a plurality of wheel bearings, a plurality of McPherson style lower control arms and a plurality of structures to support the steering function. The rear suspension  120  subframe is further comprising a metal frame for mounting the suspension parts and for attaching the subframe to the spaceframe  32 , a plurality of shock absorbers, a plurality of dampers, a plurality of wheel hubs, a plurality of constant velocity joints, a plurality of brakes and supporting components that support a parking brake function, a plurality of wheel bearings and a plurality of double-A style lower and upper control arms and a structure for routing the parking brake cables. In a preferred embodiment, both rear and front suspension  118  subframes is further comprising the mechanisms to adjust alignments of the wheels. 
         [0051]    For the two wheel drive (2WD) variant of the system, for example, a 4-by-2 configuration, constant velocity joints are not required on the non-driving axles. The vehicle may have a plurality of rear suspension  120  subframes, depending upon how many axles the vehicle comprises. In-hub wheel motors may be used in some variant of the system. In this case, since the front motor-generators and/or the rear motor-generators are mounted near the wheel hub assemblies, constant velocity joints will not be required. 
         [0052]    Other variants of the suspension system or its subframes may be used to substitute the McPherson and double-A arm implementation of the preferred embodiment. Options includes but not limited to multilink and leaf springs. 
         [0053]    The anti-lock enabled hydraulic brake  124  system is similar to that in a prior art vehicle like a 2007 Toyota Highlander. The hydraulic brake  124  system comprises a vacuum-assisted master cylinder, a vacuum pump, a brake fluid tank, a plurality of brake fluid hoses, a plurality of anti-lock brake (ABS) bleed valves and a hydraulic brake  124  at each drive wheel  34 . Any power-assisted brake system with mechanical backup and dynamic control of the brake force may be also be used as a substitute. When commanded by the vehicle control computer  70 , the bleed valves are opened to reduce the mechanical brake forces either because of output of the anti-lock brake or traction control algorithm or to prevent over-compensation by the braking forces generated by the electrical regenerative brake method. 
         [0054]    Referring now to  FIG. 9 , the electric parking brake  134  comprises a parking brake handle, a cable pull system  114  and an electric parking brake electronic control unit  86 . The purpose of the electric parking brake  134  is to apply brake force to two or more drive wheels when the vehicle is in Park mode. Another purpose of the electric parking brake  134  is to allow the operator to engage and disengage the parking brake manually. Due to the absence of an automatic transmission as in a prior art, the current invention requires the electric parking brake  134  to prevent movement when the vehicle is unattended. The electric parking brake electronic control unit  86  is connected to the vehicle control bus  76 , which supplies power to the electric parking brake  134  and a data communication channel with the vehicle control computer  70 . When commanded by vehicle control computer  70 , potentially due to a change in driving mode, the electric parking brake  134  activates a servo motor to apply tension on the cable pull system  114  until it reaches a locked position. The cable pull system  114  is attached to the parking brake support features in said rear suspension  120  subframe. The tension causes said brake system to engage, hence applying brake forces to the drive wheels, and simultaneously causes the parking brake handle to rise, indicating to the operator that the electric parking brake  134  is engaged. The operator may disengage the electric parking brake  134  by pushing a mechanical button on the parking brake handle to release the parking brake from the locked position. 
         [0055]    In order to reduce aerodynamic drag during high-speed cruising, a mechanism that allows run-time adjustments of ground clearance may be incorporated into the suspension. This mechanism may be powered by a set of hydraulic or electric actuators (such as worm drives). One possible implementation to push the drive wheel  34  assemblies downward, and thus lifting the vehicle to create more clearance. Another possible implementation is to install hinges in the spaceframe  32  to lower/rise the entire front and rear suspension  120  assembly. 
         [0056]    Propulsion. 
         [0057]    In a preferred embodiment, referring now to  FIG. 3 , the propulsion system  96  comprises a plurality of high-power motor-generators  18  on the rear axle and a plurality of continuous-duty motor-generators  16  on the front axle, four dissimilar high-power vector-drive motor controllers  24  and anti-lock brake bleed valve actuators. The two sets of motor-generators may be optimized at different rotational speeds in order to maintain high overall efficiency over any given drive cycle. The two sets of motor-generators can be rated at different power and voltage levels. The power distribution between the front and rear motor-generators are controlled by the vehicle control computer  70  of the vehicle control system  138 . The main purpose of the propulsion system  96  is to provide the vehicle the ability to accelerate and decelerate longitudinally in either direction. Another purpose of the propulsion system  96  is to provide regenerative braking capability to convert kinetic energy into electrical energy. Another purpose of the propulsion system  96  is to provide traction control similar to a conventional fully mechanical all-wheel-drive system. Each of the motor-generators is connected to a drive wheel  34 . Another purpose of the propulsion system  96  is to reduce frictional and parasitic losses and to lower the weight of the current invention compared to prior arts, further increasing the energy efficiency of the current invention. 
         [0058]    In a preferred embodiment, the liquid-cooled continuous-duty motor-generators  16  and the liquid-cooled high-power motor-generators  18  the propulsion system  96  are independently connected to the wheels through constant velocity joints (or CV-joints), without transmissions or differentials. The weight and the frictional losses of the propulsion system  96  are significantly reduced by not having transmissions and differentials. The plurality of vector-drive motor controllers  24  are further commanded by the vehicle control computer  70  through four independent electrical or optical connections. Fiber optics with pulse-width modulated signals or digital signals are possible implementations of these connections. The motor controllers  24  decode the signals from the vehicle control computer  70  and translate them to motor outputs such as torques. Wheel speed sensors, such as optical encoders, Hall-effect sensors and inductive rotational speed sensors, mounted on each of the continuous-duty motor-generators  16  and each of the high-power motor-generators  18 , measure wheel speeds. And, based on these inputs, the vehicle control computer  70  then calculates the slip ratio of each drive wheel  34  to ascertain road conditions. The vehicle control computer  70  electronically adjusts the power output of each drive wheel  34  via the motor controllers  24  to optimize the traction produced at each wheel based on the algorithms for anti-lock brake control, traction control and roll and yaw electronic stability controls, in essence fulfilling the purpose of a conventional all-wheel-drive (AWD) system. 
         [0059]    In a preferred embodiment, regenerative braking is accomplished through the vector-drive motor controllers  24 . When the brake pedal  66  is depressed, the vector-drive motor controllers  24  are commanded by the vehicle control computer  70  to create reverse torque on the drive wheels, thus putting the front motor-generators and rear motor-generators in regenerative mode. Kinetic energy is converted into electrical energy by the continuous-duty motor-generators  16  and the high-power motor-generators  18  and absorbed by an array of capacitors known as an ultracapacitor  22 , which is, and a battery array  20  in the primary electrical system. Reverse torque is created at each drive wheel  34  during the process and slows the current invention. If the energy storage devices are at full capacity, the excess electrical energy may be dissipated through a shunt resistor connected to the power distribution and management bus  80  or by commanding the high-power motor-generators  18  to commutate in reverse; combined with said mechanical brakes, the system can achieve the desired braking force. To maintain full mechanical backup, depressing the brake pedal  66  causes an increase in the hydraulic pressure in anti-lock enabled hydraulic brake  124  system. In the absence of regenerative braking, potentially due to a failure in the system, said pressure is sufficient to operate the mechanical brake to its full extent to slow the vehicle. In the presence of regenerative braking, the anti-lock brake bleed valve actuators are electronically activated by the vehicle control computer  70  to relieve said pressure to reduce the effects of mechanical braking. 
         [0060]    Additional benefits of having a direct-drive electric propulsion system  96  include reduced torque steering and body-twisting effect. The motor-generator pairs and the motor controllers  24  can be air-cooled or liquid-cooled, depending on the demand. Alternatively, the propulsion system  96  may comprise of two motor-generators and motor controllers  24  instead of four in either a rear-wheel-drive (RWD) or front-wheel-drive (FWD) mode configuration. In a two-wheel-drive mode, the vehicle control system  138  electronically adjusts the power output of each wheel to reproduce the mechanical responses typically found in a prior art two-wheel-drive system. 
         [0061]    Alternatively, any two motor-generators on an axle may be combined using a conventional differential, similar to the rear or front drive axle of a conventional automobile. 
         [0062]    In-hub wheel motors may be used in some variant of the system. In this case, since the front motor-generators and/or the rear motor-generators are mounted near the wheel hub assemblies, constant velocity joints will not be required. 
         [0063]    Controls. 
         [0064]    In a preferred embodiment, referring now to  FIG. 4 , the fail-safe vehicle control system  138  comprises a vehicle management computer  72 , a vehicle control computer  70 , a steering wheel angle sensor  84 , a wheel speed sensor at each wheel, an inertial sensor unit  64 , an accelerator pedal  68 , a brake pedal  66 , a drive mode selector  74 , an instrument cluster  88  and a vehicle control bus  76 . In a preferred embodiment, these two electronic controllers reside in the same integrated electronic assembly, hence be able to share data via a local data bus through the backplane of the electronic assembly. The main purpose of the vehicle control computer  70  is to execute vehicle control laws comprising software algorithms for controlling acceleration, deceleration, regenerative braking, power management, steering, AWD electronic differentials, anti-lock brakes and electronic stability controls (hereinafter referred to as “the control laws” collectively). Another purpose of the vehicle control computer  70  is to sample, filter and analyze the input signals for the control laws. The vehicle control computer  70  samples electronic signals including but limited to the drive mode selector  74  position, steering wheel position, wheel speeds, inertial measurements, the accelerator pedal  68  position and the brake pedal  66  position. These inputs are then fed into the control laws, which will calculate the optimal motor outputs to collectively produce the desirable mechanical response at the drive wheels. The results of such calculation is then sent to the motor controllers  24  and translated into motor outputs. The vehicle control computer  70  comprises a real-time, fail-safe microprocessor, supported by the necessary said input and output capabilities such as analog inputs and outputs, digital inputs and outputs and connection to the vehicle control bus  76 , an opto-isolated data connection to the power management unit  46  and opto-isolated digital interfaces to each of the four the motor controllers  24 . 
         [0065]    The main purpose of the instrument cluster  88  is to display the digital signals on the vehicle control bus  76  into a human-readable form to inform the driver of the current invention the status of the vehicle. The instrument cluster  88  is typically located on the dashboard. 
         [0066]    The main purpose of the drive mode selector  74  is to simulate the mode selection control of an automatic transmission of a prior art automobile. In a preferred embodiment, the drive mode selector  74  comprises four electronic buttons each representing one of the four driving modes: Park, Reverse, Neutral and Drive. The drive mode selector  74  is connected to the vehicle control bus  76  and is an essential input device to the vehicle control computer  70 . An electronic signal is sent to the vehicle control computer  70  via the vehicle control bus  76  when one of the four buttons is depressed. The vehicle control computer  70  then determines the proper driving mode the system is in, based on operator&#39;s input and the statuses of safety interlocks. 
         [0067]    In a preferred embodiment, referring now to  FIG. 6 , the vehicle control bus  76  comprises a high-speed digital communication medium, a plurality of electrically conductive media for delivery of electrical power and a rechargeable backup battery  62 . The main purpose of the vehicle control bus  76  is to allow data exchange between the different components of the vehicle control system  138 . Another purpose of the vehicle control bus  76  is to provide uninterruptible power to all safety related functions of the current invention comprising to the brake system, electric-assist steering column  82 , safety restraints, wipers, headlamps, signal lamps, tail lamps and the instrument panel. During operation, the electrical power available on the vehicle control bus  76  is generated by a step-down converter  60 , which is part of the power distribution and management bus  80 , and delivered under the power management unit&#39;s control. The main purpose of the high-speed digital communication medium is for exchanging electronic data essential to the proper functioning of the vehicle control system  138 . The high-speed digital communication medium is typically implemented using an industrial standard controller area network (or CAN) bus. Another possible purpose of the vehicle control bus  76  is to provide legacy voltage (e.g. 12 VDC) to prior art components that has not been retrofitted to use the common bus voltage on the vehicle control bus  76 . When applicable, additional wiring and a legacy voltage power supply  132 , which is essentially a DC-to-DC converter, provides the voltage needed. 
         [0068]    The main purpose of the backup battery  62  is to provide a temporary voltage hold-up when the low voltage supply from the power management unit  46  failed or during startup or shutdown processes of the current invention when the high voltage supply is disabled for safety reasons. The backup battery  62  is constantly being recharged to its holdup voltage during operation. 
         [0069]    Depending on the level of sophistication of the actual implementation, vehicle control computer  70  could potentially be an array of such computers, each one performing similar functions hence providing hardware redundancy to satisfy fail-safe and/or fail-operational requirements. Another essential function of the VMC is the control of acceleration and regenerative braking During deceleration, the front motor-generators and the rear motor-generators continue to spin due to the inertia of the vehicle. The regenerative braking control algorithm in the VMC will instruct the PDU in the primary electrical system to direct the electrical current generated by the wheel motors to the battery pack to be stored. 
         [0070]    During normal operation, the vehicle control computer  70 , the vehicle management computer  72 , the power management unit  46  and the battery controller  26  and the motor controllers  24  will closely monitor the status of all components for any electrical or mechanical anomalies. Visual indications to the driver may also be provided as to the status of the vehicle. 
         [0071]    Optionally, the current invention may implement a user-activated override switch—allowing the driver to temporarily disable all or a subset of the system monitoring function. This will allow the vehicle control computer  70  to overload the system to output maximum performance as needed, at the expense of potential overheating and shortening the useful lives of the components. 
         [0072]    In a preferred embodiment, referring now to  FIG. 7 , the vehicle management bus  78  comprises a low-speed digital communication medium and a plurality of electrically conductive media for delivery of electrical power. The main purpose of the vehicle management bus  78  is to allow the vehicle management computer  72  to receive control signals from and to deliver commands to non-real-time subsystems including but not limited to said body controls  92 , thermal management, interior climate control  102 . During operation, the electrical power available on the vehicle control bus  76  is generated by the step-down converter  60 , which is part of the power distribution and management bus  80 , and delivered under the power management unit&#39;s control. The main purpose of the low-speed digital communication medium is for exchanging electronic data essential to the proper functioning of non-real-time subsystems. The high-speed digital communication medium is typically implemented using an industrial standard controller area network (or CAN) bus. 
         [0073]    Certain failure modes of the electronic components in the electric propulsion system  96  may lead to differential torque between the left and the right of the vehicle. For example, if one of the four motor controllers  24  fails and if not handled properly, the system may create said differential torque, which may lead to complete loss of steering control. The vehicle control computer  70  further comprises monitoring circuitry and software algorithms to detect such failure modes and handle the failures accordingly. Motor controllers  24  comprise local fault detection circuitries and electrical means for the vehicle control computer  70  to disengage one or more motor controllers  24  when a local failure occur. The electric-assist steering column  82  and the regenerative brake system further comprise a non-electrical means for the operator to maintain steering and braking controls respectively. 
         [0074]    Electrical System. 
         [0075]    Referring now to  FIG. 5 , The primary electrical system comprises a power distribution and management bus  80 , a battery array  20 , a battery controller  26 , a shunt resistor unit, an ultracapacitor  22 , a power management unit  46 , a step-down converter  60 , a charger unit and an optional adaptor to an off-board support station. The main purpose of the primary electrical system is to provide power to the propulsion system  96  and to recapture energy during regenerative braking. Another purpose of the primary electrical system is to provide electrical energy to the vehicle said control bus and said vehicle management bus  78 . 
         [0076]    The main purpose of the power distribution and management bus  80  is to provide a digital communication channels for electronic data essential to the proper functioning of the high power devices comprising the propulsion system  96 , the battery array  20 , the ultracapacitor  22 , the power management unit  46 , the charger unit and the optional adaptor to the off-board support station. Another purpose of the power distribution and management bus  80  is to provide a low-voltage supply to the vehicle control bus  76  and vehicle management bus  78 . 
         [0077]    The power management unit  46  further comprises an electromagnetic interference filter  48  circuit and a power management electronic control unit  130 . The main purpose of the power management unit  46  is to optimize the distribution of electrical energy across a plurality of devices on the power distribution and management bus  80 . Another purpose of the power management unit  46  is to transfer energy from one high-power energy storage device to another. The power management electronic control unit  130  comprises the microprocessor and switching circuits to effectively calculate the desired energy distribution and to perform the transfers of energy. For example, when the current invention is at a complete stop, energy is transferred from the battery array  20  to the ultracapacitor  22  to prepare the primary electrical system for surge in power output due to an imminent acceleration. Another purpose of the power management unit  46  is to provide a low-voltage supply to the vehicle control bus  76  and vehicle management bus  78 . Another purpose of the power management unit  46  is to filter the conducted electromagnetic noises from the high-power devices on the power distribution and management bus  80  and prevent them from entering the vehicle control bus  76  or vehicle management. Radiated electromagnetic noises are contained by shielding. 
         [0078]    The main purpose of the step-down converter  60  is to step-down the voltage on the high-voltage bus of the power distribution and management bus  80  and to regulate the output voltage on the low-voltage bus. 
         [0079]    The battery array  20  comprises a battery controller  26 , a series of interconnected rechargeable battery cells, a plurality of temperature sensors, a plurality of current sensors and a plurality of voltage sensors. The main purpose of the battery array  20  is to provide the current invention the option to operate entirely on electricity. Another purpose of the battery array  20  is to store electrical energy for use by the propulsion system  96  and other subsystems. Another purpose of the battery array  20  to capture the excess electrical energy generated by the auxiliary power module  30  under the module&#39;s optimal operating conditions. A portion of the electrical energy generated by the auxiliary power module  30  directly powers the front motor-generators and the rear motor-generators, while the rest of the energy is diverted to the ultracapacitor  22  and the battery array  20  for storage. The battery cells are connected in such a way to create a higher voltage needed to drive the wheel motors. State-of-the-art Lithium-ion batteries offer cycle lives, energy densities and power densities suitable for an electric vehicle application. However, other rechargeable battery types, such as Nickel-Metal-Hydride, Nickel-Cadmium or Lead-Acid, may be used instead of the lithium-ion chemistry. The main purpose of the battery controller  26  is to control the charging and discharging processes of the battery cells according to their manufacturer&#39;s specifications by monitoring their state-of-charge and regulating the charge voltage. Another purpose of the battery controller  26  is to monitor for any operational anomalies, including but not limited to over- or under-voltage, over- or under-current, over- or under-temperature. Another purpose of the battery controller  26  is to attempt to rectify the situation or to shut down the battery array  20  when such operational anomalies are detected. Another purpose of the battery controller  26  is to provide a digital control interface of the battery array  20  to the power management unit  46  via the power distribution and management bus  80 . 
         [0080]    The size of battery array  20  in primary electrical system may be customized based on the application. However, in order to store the energy produced by regenerative braking and to support the efficient operation of the auxiliary power module  30 , at least some energy storage is required. 
         [0081]    The main purpose of the shunt resistor unit is to monitor the high voltage supply on the power distribution and management bus  80 . Another purpose of the shunt resistor is, during an over-voltage condition, to crowbar the bus to lower the voltage and dissipate the excess electrical energy as heat. The shunt resistor unit comprises of an analog voltage monitor, which in turn control a relay or a solid-state switch to crowbar the high voltage supply of the power distribution and management bus  80 . The same may be accomplished using a zener diode. In a preferred embodiment, the shunt resistor unit is liquid-cooled by the coolant supplied by the thermal management system  28 . The liquid cooling may be substituted by forced or natural convection cooling by air. 
         [0082]    In a preferred embodiment, the charge unit of the current invention comprises also an adapter cable to a household or industrial power grid, a charger electronic control unit, a power rectifier and optionally an inverter circuit. The main purpose of the charger unit is to enable the current invention to operate entirely on electricity, thus making it an electric vehicle. Another purpose of the charger unit is to enable the current invention to operate as a plug-in hybrid electric vehicle. Another purpose of the charger unit is to enable the current invention to operate as a grid-connected hybrid vehicle, in which the vehicle provides electrical power to the power grid. Another purpose of the charger unit is to convert the electrical energy from the power grid into the form of electrical energy usable on the power distribution and management bus  80 . The main purpose of the charger electronic control unit is to monitor and control the input and output and operating conditions of the charger unit and to shutdown the charger unit when over-voltage, over-current, over-temperature. Another purpose of the charger electronic unit is to interpret commands from and to assess and report status to the power management unit  46 , which determines the status of certain interlocks to prevent unsafe operations of the current invention. The purpose of the power rectifier is to convert the standard power grid alternative current (AC) supply into a direct current (DC) supply defined by the power distribution and management bus  80 . 
         [0083]    For a grid-connected hybrid application, which refers to an infrastructure that uses a collection of hybrid electric vehicles to power the grid during a brown-out event, an inverter unit may also be implemented. The purpose of the inverter unit is to redirect the electrical energy on the power distribution and management bus  80  back to the power grid, and in the process, converting electricity to the appropriate voltage and waveform demanded by the grid. The electrical interface may be designed to interface with a commercial electric vehicle or plug-in hybrid electric vehicle charger for a faster recharge time. 
         [0084]    Thermal Management. 
         [0085]    The thermal management system  28  comprises an electric coolant pump, an electronic control unit, a plurality of hoses, a liquid coolant and a plurality of heat exchangers  104 . The main purpose of the thermal management system  28  is to remove excess thermal energy from the subsystems of the current invention. These subsystems include but are not limited to the propulsion system  96 , the auxiliary power module  30 , the battery array  20 , the power management unit  46 , the ultracapacitor  22 , the shunt resistor unit, the vehicle control computer  70  and the vehicle management computer  72 . The coolant comprises essentially of a mixture of water and an anti-freeze agent, such as polypropylene. The electric coolant pump comprises of a water pump that is similar to those used in prior arts but driven by an electric motor instead. The purpose of the coolant pump is to circulate the coolant through the different subsystems and the heat exchanger. The purpose of the heat exchangers  104  is to release the excess thermal energy into the air flowing through the heat exchangers  104 . A heat exchanger also comprises a plurality of electric fans to increase air flow when needed. The main purpose of the electronic control unit is to control the speeds of the electric fans and the speed of the electric coolant pump based on the electronic signals received from the vehicle management bus  78 . 
         [0086]    Power Generation. 
         [0087]    The main purpose of the auxiliary power module  30  is to provide electrical energy for the proper functioning of the current invention via the power distribution and management bus  80 . Another purpose of the auxiliary power module  30  is to make the current invention capable of economically adapting to different fuel sources in the aftermarket. Another purpose of the auxiliary power module  30  is to provide the option to operate the current invention entirely on electricity. 
         [0088]    The auxiliary power module  30  is a self contained unit with its own fuel system, exhaust system and emission control if necessary. In a preferred embodiment, the auxiliary power module  30  comprises a power module electronic control unit, an air inlet, an air filter, a diesel engine, a cooling system, an electric starter generator, a voltage regulator, a fuel system, an exhaust system, an emission control, an enclosure and an electrical connection to the power distribution and management bus  80 . The main purpose of the power module electronic control unit is to monitor and control the diesel engine, much like the electronic control unit for prior art engine, and to monitor and control the voltage regulator. The purpose of the air inlet, the air filter, the fuel system, the exhaust system and the emission control is to support the operation of the diesel engine, much like a prior art vehicle. Another purpose of the power module electronic control unit is to interpret commands from and to assess and report status to the power management unit  46 . The coolant may be supplied by the current invention&#39;s thermal management system  28 . The output shaft of the diesel engine is connected to the electric starter generator, with or without gears in between. The main purpose of the starter-generator is to convert the kinetic energy of the output shaft of the diesel engine to electrical energy. Another purpose of the starter-generator is to create the initial torque necessary to start the diesel engine from stall, when commanded by the power module electronic control unit to do so. The electrical output of electric starter generator is connected to the voltage regulator. The main purpose of the voltage regular is to regulate the output voltage to meet the demand of the primary electrical system. Another purpose of the voltage regulator is to monitor input and output currents and input and output voltages and shut down the auxiliary power module  30  if over-current or over-voltage conditions are detected. The power module electronic control unit and the voltage regulator output are connected to the electrical interface to the power distribution and management bus  80 , which provides high-voltage electrical connection with the high-power devices on the bus, a low-voltage supply for low-power electronics and a digital communication channel with the power management unit  46 . 
         [0089]    The components of the auxiliary power module  30  are mounted on the enclosure. And the entire assembly is mounted in the mid section of the spaceframe  32 , substantially in the area below the second row seats. The purpose of the enclosure is to provide structural support to the components during normal operation. Another purpose of the auxiliary power module  30  is to provide mechanical support to the spaceframe  32  during normal operation. Another purpose of the auxiliary power module  30  is to provide mechanical support and to absorb impact during a vehicle collision. Another purpose of the enclosure is for attaching the auxiliary power module  30  to the spaceframe&#39;s mechanical interface for an auxiliary power module  30 . 
         [0090]    The mechanical interface and the electrical interface of the auxiliary power module  30  are defined by the specification of the current invention and are application specific, called a common interface control definition. The purpose of the common interface control definition is encourage third party and aftermarket designs, sales and serving of the auxiliary power module  30  and thus allowing the current invention to promptly adapt to consumer preferences for alternative fuel sources. Another purpose of the common interface control definition is to enable a quick and economical means to retrofit the current invention with another auxiliary power module  30  if the owner of the vehicle so choose. Another embodiment of the auxiliary power module  30  in an all-electric application the diesel engine and support hardware is substituted with electrically rechargeable energy storage device, such as another battery array  20 , another ultracapacitor  22  or a high-capacity flywheel. The power management unit  46  reconfigures itself based on the configuration data available on the power module electronic unit via the power distribution and management bus  80 , and adjusts the power management algorithm to take advantage of the additional energy storage capacity. Other embodiments may involve the use of fuel cells, hydrogen fuels, natural gas fuels, gasoline, bio-diesel, heat engines, and other systems that converts some forms of energy into electricity usable by the primary electrical system. 
         [0091]    Modes of Operations. 
         [0092]    The current invention, though not requiring an automatic transmission, simulates the ease-of-use of an automobile equipped with automatic transmission. 
         [0093]    To begin using the invention, the operator enters the vehicle and position himself in the driver seat, behind the dashboard and the instrument panel, where the operator has direct access to the steering wheel, the accelerator pedal  68 , the brake pedal  66  and the drive mode selector  74 . Once the operator authenticated himself/herself using a key, the current invention enters a stand-by mode awaiting further input from the operator. The operator select one of the four driving modes: Park, Reverse, Neutral or Drive. The operator then commands the current to accelerate by depressing the accelerator pedal  68 . To stop or decelerate, the operator releases the accelerator pedal  68  and depresses the brake pedal  66 . Other vehicle interfaces, such as turn signals, wipers, windows  14  controls, etc. are much the same as a conventional vehicle. 
         [0094]    To utilize electric fuel from the power grid to recharge the current invention, the operator will plug the power cord that is part of the onboard charger unit into a wall outlet, hence redirecting electrical energy into the current invention, which is much like a conventional electric vehicle. The electric propulsion system  96  draws its electrical energy from the primary electrical system. The energy is used to accelerate the vehicle. Some of this energy is recovered during regenerative braking. The vehicle control system  138  adjusts the power output of the motor-generator at each drive wheel  34  as needed, based on operator inputs, inertial measurements and road conditions measured. Other auxiliary features operate in the essentially same way as they do in a conventional vehicle from the operator&#39;s standpoint. 
         [0095]    Since other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, the invention is not considered limited to the example chosen for purposes of disclosure, and covers all changes and modifications which do not constitute departures from the true spirit and scope of this invention. 
         [0096]    Having thus described the invention, what is desired to be protected by Letters Patent is presented in the subsequently appended claims. 
         [0097]    While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.