Abstract:
A drive-train for a fuel-efficient wheeled vehicle includes a first internal combustion engine and a second internal combustion engine of lesser power adapted to drive a generator. An electric motor is adapted to drive the vehicle primarily during cruising mode operation. The first engine is employed primarily to provide maximal power to the vehicle for acceleration, hill-climbing and towing. The power from both the motor and first engine can be selectively combined for varied conditions of operation of the vehicle.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention concerns fuel-efficient vehicles, and more particularly relates to automotive vehicles powered by both an electric motor and an internal combustion engine, popularly known as “hybrid” vehicles. 
   2. Description of the Prior Art 
   Hybrid vehicles have been developed to improve the fuel efficiency of motor vehicles. They are powered by both an internal combustion engine and an electric motor energized by rechargeable storage batteries. The combined power of both power sources is used when maximal power is needed, such as for acceleration, towing heavy loads or climbing steep grades. The engine is generally used for cruising, and is usually severely down-sized to achieve fuel efficiency. The electric motor can be used alone but only for relatively short distances because of the limited power capacity of the batteries which soon become discharged and lose their power. Consequently, the electric motor is usually simply used to augment the power of the engine for some fairly short duty cycles such as to quickly accelerate the vehicle from a standing start and for passing. Performance can deteriorate for longer heavy duty cycles such as when climbing long grades or towing heavy loads when the down-sized engine may have to toil alone without assistance from the electric motor after the batteries become discharged. 
   Some hybrid vehicles have been modified to increase the cruising range of the electric motor by adding substantial numbers of storage batteries to the vehicle, and then by charging these batteries overnight using household electricity. Although such vehicles can travel as much as 60 miles between charges, and with little use of gasoline, the cost of the extra batteries is considerable. The batteries also have limited life expectancy, and the added weight of the batteries adversely affects the vehicle&#39;s fuel efficiency. 
   Examples of hybrid vehicles involving an internal combustion engine and one electric motor are found in the following U.S. Pat. Nos. 
   
     
       
             
           
         
             
                 
             
           
           
             
               5,513,719 
             
             
               5,788,003 
             
             
               6,044,922 
             
             
               6,209,672 
             
             
               6,328,671 
             
             
               6,668,954 
             
             
               6,706,789 
             
             
               6,712,165 
             
             
               6,958,549 
             
             
               6,995,480 
             
             
               7,004,273 
             
             
               7,028,796 
             
             
                 
             
           
        
       
     
   
   Hybrid vehicles involving a single internal combustion engine in exemplified or suggested association with two or more electric motors are disclosed in the following U.S. Pat. Nos. 
   
     
       
             
           
         
             
                 
             
           
           
             
               5,343,971 
             
             
               6,717,281 
             
             
               6,856,035 
             
             
               6,959,237 
             
             
               6,962,224 
             
             
               6,965,173 
             
             
               7,044,255 
             
             
                 
             
           
        
       
     
   
   Hybrid vehicles have high initial and maintenance costs due to the need for an especially down-sized engine, batteries of high amperage capacity, and the associated specialized control components. These requirements make it difficult to apply current hybrid technology as after-market modifications for converting current standard automotive vehicles into fuel-efficient hybrid vehicles. 
   The present invention provides cost-effective solutions to the problems cited above. 
   Firstly, it enables the vehicle to cruise for long distances powered by an electric motor without the need for a substantially increased number of high-capacity batteries. Instead, the electric motor is energized by an on-board generator powered by a fuel-efficient internal combustion engine. This permits the vehicle to cruise over long distances with maximal fuel-efficiency using mainly the power from its electric motor. The weight of the added equipment need not significantly affect the fuel economy of the vehicle, and the cost should compare favorably with that of current hybrid vehicles. 
   Secondly, this invention achieves the desired fuel economy for long distance cruising without sacrificing the vehicle&#39;s performance, particularly in acceleration, load-bearing, towing and hill-climbing. This is done through the use of a separate auxiliary “accelerator” engine to add to the power of the electric motor whenever more power is needed. Since the accelerator engine is usually operated only for short periods of time, and is usually not operated while the vehicle is traveling over long distances at cruising speed, its size, power and fuel consumption need not substantially impact the over-all fuel efficiency of the vehicle. Hence, the operator can enjoy the comfort and confidence of having as much power as he desires under the hood and yet, with properly prudent driving technique, cruise with high fuel-efficiency over long distances. 
   This invention further permits great versatility in the choice of both the generator engine and accelerator engine. For example, the generator engine can be a small diesel engine, powerful enough to keep the batteries fully charged, and the accelerator engine can be a powerful gasoline engine, such as a Wankel rotary engine, for quick throttle response and lively performance. 
   The power train aspect of the present invention is easily adaptable for use as an add-on after-market modification of some existing motor vehicles which are thereby converted into fuel-efficient hybrid vehicles in a cost-effective manner. 
   It is accordingly a primary object of this invention to provide a hybrid vehicle capable of cruising for long distances using power from an electric motor without the need for high storage battery capacity. 
   It is an additional object of the present invention to provide a hybrid vehicle capable of cruising for long distances with maximal fuel-efficiency, without sacrifice of acceleration, hill climbing, and load-carrying capabilities. 
   It is another object of this invention to provide a fuel-efficient hybrid power train which can be installed into an existing automotive vehicle as an after-market add-on modification requiring minimal changes in said vehicle. 
   In one aspect of the present invention, a conventional non-hybrid vehicle having a regular engine with a horsepower in the range of about 100 to 350, a 12 volt battery, and a generator that is belt-driven by the vehicle&#39;s drive shaft is converted into a hybrid vehicle by the introduction of the following features:
     a) an electrically actuated motor of about 50 to 120 horsepower which serves as the main source of power to maintain the vehicle at cruising speed for long distance travel,   b) a relatively small, fuel-efficient second internal combustion engine of about 50 to 120 horsepower henceforth referred to as a “generator” engine that drives said generator, and   c) control means causing said regular engine, henceforth referred to as the first or “accelerator” engine, to operate only when the vehicle requires additional power, as for acceleration, hill climbing, and carrying heavy loads.   

   In effect, such converted hybrid vehicle utilizes said motor as its primary source of power for cruising travel, and employs the accelerator engine simply as an auxiliary engine to be used only when additional power is needed. The ratio of the horsepower of the accelerator engine to the horsepower of the generator engine is preferably in the range of 1.5:1 to 3:1. 
   For ease of operation, the generator engine can be programmed to run automatically whenever the battery needs to be charged and to stop automatically when the battery is fully charged. For added fuel-efficiency, the electric motor can be configured as a motor/generator to charge the battery through regenerative braking, a technology which is well known in the art. For further ease of operation, the accelerator engine can be caused to start automatically whenever the gas pedal is depressed beyond what is needed to run the electric motor at full power, and to be automatically coupled to the output shaft of the electric motor, when its power is needed, through a suitable automatic clutch mechanism such as an overriding sprag clutch. Further savings in fuel consumption can be achieved if the accelerator engine is configured to be automatically shut down, namely deprived of fuel whenever the vehicle is being maintained at cruising speed by the electric motor alone. This may be controlled by the degree to which the gas pedal is depressed. Alternatively, start-up, shut down, engagement and disengagement of the accelerator engine may be controlled through the vehicle cruise control system in response to input signals from speed sensors and/or load sensors associated with the driving wheels. 
   In a further aspect of the present invention, a hybrid automotive vehicle is provided having a power train comprised of:
     1) a first internal combustion “accelerator” engine,   2) speed change transmission means having an input shaft which receives power from said first engine,   3) an electric motor having sufficient power to maintain said vehicle at an acceptable cruising speed and delivering said power in a manner to controllably receive additional power from said first engine, and   4) an electrical supply system comprised of a) a second internal combustion “generator” engine of lesser power than said first engine, b) an electrical generator driven by said second engine, and c) a rechargeable storage battery interactive between said generator and motor.   

   In preferred embodiments, releasable coupling means are interactive between said accelerator engine and transmission means, enabling controlled automatic transfer of power to said transmission means. Suitable coupling means include free wheeling devices such as an overriding sprag clutch. 
   Said conveyance of power serves to accelerate said vehicle from a standing start to cruising speed by the combined power of said electric motor and said accelerator engine, and then, when the operator partially releases the gas pedal to stop the acceleration and to simply maintain the vehicle at cruising speed by using power from the electric motor alone, the fuel supply to said accelerator engine is diminished then stopped, causing said accelerator engine to slow down and stop, and as said accelerator engine slows down below the speed of said electric motor, said engine is automatically decoupled from said transmission input shaft through the function of said sprag clutch. Then, if or when the operator depresses the gas pedal again to provide more power than that produced by said electric motor, said accelerator engine is automatically restarted and speeded up to match the speed of said electric motor, causing said accelerator engine to be automatically coupled to said transmission input shaft through the action of said sprag clutch. 
   The aforesaid hybrid vehicle of this invention achieves four desirable results, namely:
     a) It enables said electric motor, powered by said electric generator assembly, to maintain the vehicle at cruising speed with reduced fuel consumption per unit of distance traveled.   b) It enables the vehicle to accelerate quickly to cruising speed through the combined power of the electric motor and the accelerator engine.   c) It enables the power train, including said accelerator engine, to remain ready to be activated whenever increased power is needed. and   d) It enables the operator to selectively control the operation of said motor and said accelerator engine, including the automatic engagement and disengagement of said accelerator engine by simply depressing or releasing the gas pedal in the same manner as would have been required if he were operating a standard non-hybrid motor vehicle.   

   Said releasable coupling means may be a friction clutch such as the type used with standard manual transmissions, a fluid torque converter of the type generally used with automatic transmissions, a centrifugal clutch, electromagnetic clutch, or other suitable types of releasable coupling means. 
   In an alternative embodiment, the accelerator engine is coupled to the speed change transmission in the conventional manner (i.e., via a friction dry plate clutch in the case of a manual transmission, or via a fluid torque converter in the case of an automatic transmission) and the vehicle is accelerated from a standing start to cruising speed by power from the accelerator engine alone. After the vehicle reaches cruising speed, the speed change transmission is shifted to neutral and the vehicle is placed in a free-wheeling state. 
   The electric motor may be coupled to a pinion drive of a differential, completely bypassing the speed change transmission, using a power transfer means which may be an endless chain connected to sprockets, or spur gears, or combinations thereof. For added speed flexibility, a continuously variable torque converter may be installed between the electric motor output shaft and said power transfer means. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     With these and other advantages in view, the invention is disclosed in the following description which will be more fully understood when read in conjunction with the following drawings in which: 
       FIG. 1  is a schematic top view, partly in section, of an embodiment of the hybrid vehicle of this invention equipped with an automatic transmission. 
       FIG. 2  is a magnified fragmentary view of a portion of  FIG. 1 . 
       FIG. 3  is a schematic top view, partly in section, of a first alternative embodiment of this invention equipped with a manual transmission. 
       FIG. 4  is a magnified fragmentary view of a portion of  FIG. 3 . 
       FIG. 5  is a schematic top view of a second alternative embodiment of this invention. 
       FIG. 6  is a schematic top view of a third alternative embodiment of this invention. 
       FIG. 7  is a schematic top view of a fourth alternative embodiment of this invention. 
       FIG. 8  is a schematic top view of a fifth alternative embodiment of this invention. 
   

   For clarity of illustration, details which are not relevant to the invention, such as engine mounts, electrical circuits, transmission mounts, internal parts of the speed change transmission, differential, transaxle, sprag clutch and continuously variable torque converter, etc., have been omitted from the aforesaid drawings. 
   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to the above drawings wherein one character designates one part of the vehicle,  FIG. 1  shows the vehicular chassis  11  connected to the front bumper  12  and rear bumper  13 , and supported by front wheels  14  and rear wheels  15 . 
   Accelerator engine  16 , mounted on chassis  11 , has flywheel  17  and output shaft  18  interactive with releasable coupling means in the form of sprag clutch  20 , whose inner race  19  is fixedly mounted upon output shaft  18 . Outer race  21  of sprag clutch  20  is fixedly mounted within the hub  40  of the armature  22  of electric motor  23  so that armature  22  is freely rotatable on output shaft  18  in one direction, particularly when armature  22  is spinning faster than output shaft  18 , but would be fixedly locked to output shaft  18  if shaft  18  were to tend to spin faster than armature  22 . Field coils  24  of electric motor  23  are mounted on bell housing extension  25  which is fixedly bolted to accelerator engine  16 , and upon which bell housing  26  of automatic transmission  27  is in turn fixedly bolted. 
   Armature  22  is connected to electric motor output shaft  28  which extends through rear wall  29  of bell housing extension  25  and is supported by bearings  30  mounted on rear wall  29 . Electric motor output shaft  28  terminates in a motor flywheel  31  which supports the driving vanes  32  of fluid torque converter  33  whose output shaft  34  extends rearward to become the input shaft  35  of automatic transmission  27 . 
   Electric motor  23  is energized by electricity generated by generator  36  from power produced by generator engine  37 , and supplemented by electricity stored in battery  38 . 
   To start the vehicle, the operator depresses the accelerator (or “gas”) pedal which activates a rheostat that controls how much electricity will be allowed to flow from battery  38  and generator  36  to electric motor  23  which then begins to spin armature  22 , output shaft  28  and driving vanes  32  of fluid torque converter  33 . Generator engine  37  may be configured to start running as soon as a substantial amount of current begins to flow from battery  38  to motor  23  or it may be programmed to automatically start as soon as the battery  38  is discharged to a predetermined degree. When the gas pedal is depressed far enough for full power to be produced by electric motor  23 , the gas pedal also closes a start switch for the accelerator engine  16 , turns on the ignition and begins to open the gas supply so that accelerator engine  16  starts running, initially at “idle” speed. The transmission  27  may then be shifted to “drive” or “reverse.” When the gas pedal is depressed further the accelerator engine  16  will run faster and eventually match the rotational speed of electric motor  23 . At this point the inner race  19  and other race  21  of sprag clutch  20  will automatically lock together and couple output shaft  18  to armature  22  so that combined power from both the accelerator engine  16  and electric motor  23  will be transmitted to fluid torque converter  33  thence to automatic transmission  27 , and thence to differential  34  and rear wheels  15 . 
   When the vehicle has reached the desired speed, the operator simply eases up on the gas pedal until the accelerator engine  16  slows down and stops, and then maintains slight pressure on the gas pedal to regulate power from the electric motor  23  to maintain the cruising speed of the vehicle. When more power is needed to accelerate or climb a grade the operator needs only to depress the gas pedal to generate more power from electric motor  23 , and if necessary depress it further to restart and run accelerator engine  16  to supply added power. These are exactly the same maneuvers that the operator would have had to do were he driving a currently standard vehicle similarly equipped with an automatic transmission. 
   Turning now to  FIG. 3 , there is shown the first alternative embodiment of the invention applied to a front-engine/rear-wheel drive vehicle with manual transmission. Accelerator engine  41  has an output shaft  42  upon which is fixedly mounted the inner race  43  of sprag clutch  44 . The outer race  45  of sprag clutch  44  is fixedly mounted on the hub  46  of the armature  47  of electric motor  48 . When both accelerator engine  41  and electric motor  48  are in operation, they rotate coaxially in the same direction. Sprag clutch  44  permits electric motor  48  to rotate freely in its operational direction relative to output shaft  42 , but not in reverse, so that if said output shaft  42  were to tend to rotate faster than electric motor  48 , sprag clutch  44  will lock the two together, causing them to turn at the same speed and transmit their combined power through electric motor output shaft  49  to friction clutch  50  which is a standard dry plate clutch operated through a clutch foot pedal. 
   To operate the vehicle, the accelerator engine is started and run initially at idle speed, causing the sprag clutch to engage so that both engine  41  and electric motor  48  are running at the same speed. The clutch is depressed, the transmission is shifted to first gear, and the accelerator pedal is depressed to feed current to electric motor  48  and, if depressed further, to feed fuel to engine  41 , whereupon the clutch pedal is gradually released to engage the clutch  50  and move the vehicle on the combined power of accelerator engine  41  and electric motor  48 . The transmission  51  is shifted through the gears in the usual manner, and when cruising speed is reached the operator eases on the accelerator pedal to cause accelerator engine  41  to slow down to idle speed and yet allow electric motor  48  to produce enough power to maintain the vehicle at cruising speed. The accelerator pedal is calibrated in such a way that when it is depressed one-third of the way down only a rheostat which controls power from the electric motor  48  is operated, and then when the pedal is depressed further, increasing amounts of fuel are fed to accelerator engine  41 . When the accelerator engine slows below the speed of electric motor  48 , the sprag clutch  44  automatically disengages the output shaft  42  of engine  41  from the hub  46  of electric motor  48 , thereby disengaging accelerator engine  41  from transmission  51 . The vehicle then cruises solely on power from electric motor  48  which draws current from battery  52  which is kept fully charged by generator  53  powered by generator engine  54 . 
     FIG. 5  illustrates a second alternative embodiment adapted to be more easily retro-fitted to a standard front-engine/rear wheel drive vehicle. Accelerator engine  55  is the stock regular engine of the vehicle, mated to a standard transmission  56  which may be manual or automatic, transmitting power through propeller shaft  57 , pinion  58  and differential  59  to drive (rear) wheels  60 . Electric motor  61  supplies power through splined short propeller shaft  62 , jack shaft  63 , drive chain  64 , sprockets  65  and  66 , and thence to pinion  58 . Generator engine  69  powers generator  68  which keeps battery  67  fully charged, and also supplies additional power to electric motor  61  as needed. 
   The vehicle is accelerated from a standing start to cruising speed by power from the accelerator engine in the usual manner. The transmission is then shifted to neutral and the vehicle is placed in a free wheeling state. Electric motor  61  is then speeded up to provide power for cruising. Meanwhile accelerator engine  55  is on standby to produce additional power as needed. As explained above, this vehicle can travel at cruising speed with less fuel consumption per distance traveled by using the electric motor/electric generator system as compared to traveling long distances on the larger regular (accelerator) engine which consumes more fuel to travel the same distance. 
     FIG. 6  illustrates a third alternative embodiment of the invention adapted to be easily retro-fitted to a front engine/rear wheel drive vehicle modified to give the electric motor more flexibility of operation at a wider range of speeds and having more torque flexibility as well. Accelerator engine  70  is the regular engine of the vehicle, mated to a standard transmission  71  which may be an automatic transmission or a manual transmission connected to propeller shaft  72 , pinion  73 , differential  74  and wheels  75 . The vehicle is accelerated to cruising speed with power from accelerator engine  70  through speed change transmission  71  in the usual manner. When cruising speed is reached, transmission  71  is shifted to neutral, placing the vehicle in a free wheeling state, and fuel flow to engine  70  is cut off. Electric motor  76  is speeded up to deliver power through drive pulley  77 , drive belt  78  and driven pulley  79  of a movable sheave continuously variable ratio torque converter, thence through splined short propeller shaft  80 , jack shaft  81 , sprockets  82  and  83  and endless chain  84 , thence to pinion  73  to maintain the vehicle at cruising speed. Battery  85  supplies power to electric motor  76 . Generator  86 , powered by generator engine  87 , supplies electricity to battery  85  to keep it fully charged at all times. 
     FIG. 7  shows how the invention may be fitted or retro-fitted to a front engine/front wheel drive vehicle. Accelerator engine  88  is a regular engine mated to a transaxle  89  which drives half-shafts  90  and front driving wheels  91 . The vehicle is accelerated to cruising speed by power from engine  88 , coursed through transaxle  89  and wheels  91 . After cruising speed is reached, the transaxle is shifted to neutral, placing the vehicle in a free wheeling state. Electric motor  92  is then speeded up to transmit power through splined short propeller shaft  93  to jack shaft  94 , sprockets  95  and  96  and endless chain  97 , thence to pinion  98 , differential  99  and wheels  100 , to maintain the vehicle at cruising speed for economical long distance travel. Battery  101  supplies power to electric motor  92 . Electric generator  102 , powered by generator engine  103  supplies electric current to battery  101  to keep it fully charged at all times, and to supply additional current to electric motor  92  whenever necessary. 
     FIG. 8  illustrates a fifth alternative embodiment of the invention which uses an electromagnetic power clutch  115  or any similarly suitable clutch means, instead of a sprag clutch. Electric motor  110  is coupled to speed change transmission  111  which is connected to propeller shaft  112 , thence to differential  113  and drive wheels  114  in the usual manner. Electromagnetic power clutch  115  is fixedly mounted on the output shaft  116  of accelerator engine  117 . The output shaft of electromagnetic power clutch  115  is coupled to the main shaft of the rotor of electric motor  110 , which is in turn coupled to said speed change transmission  111 . Accelerator engine  117  can therefore be selectively coupled to speed change transmission  111  via electromagnetic clutch  115  and the main shaft of electric motor  110 . 
   To accelerate the vehicle, power from both the accelerator engine  117  and electric motor  110  are used. To cruise economically, accelerator engine  117  is decoupled through electromagnetic clutch  115  and stopped and the vehicle is kept at its cruising speed by power from electric motor  110  alone. Electric generator engine  119  drives electric generator  120  which supplies current to electric motor  110  and also charges battery  118 . Electric motor  110  can be configured to be a motor/generator so that it can charge battery  118  through regenerative braking. Battery  118  need not be of high capacity since electric motor  110  can be powered continuously for long distance cruising operation by generator  120 . Battery  118  is only useful to supply supplemental current to electric motor  110  and to supply current to accessory electrical devices in the vehicle, such as the radio, gauges and lights. 
   Other types of releasable couplings can be used instead of electromagnetic power clutch  115 , and may be selected from a group which includes centrifugal clutches, single disc or multiple disc clutches, cone clutches, toroidal torque converters, pawl and ratchet freewheeling clutches, sprag clutches or any combination thereof. 
   While particular examples of the present invention have been shown and described, it is apparent that changes and modifications may be made therein without departing from the invention in its broadest aspects. The aim of the appended claims, therefore, is to cover all such changes and modifications as fall within the true spirit and scope of the invention.