Abstract:
A fuel-efficient automotive vehicle is provided having a power train including a primary internal combustion engine, an auxiliary engine, and a coupling system which selectively transfers power from the auxiliary engine to the primary engine when the speed of operation of the auxiliary engine equals the speed of the primary engine. The speeds of both engines are controlled by separate gas pedals conventionally located within the vehicle. The primary engine is of smaller power and better fuel efficiency than an engine which would generally be required by the vehicle. Although the primary engine can maintain the vehicle at a cruising speed, it relies upon the added power of the auxiliary engine for acceleration and hill-climbing.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to vehicles having multiple power sources to achieve improved fuel-efficiency for cruising without decrease in performance in acceleration and hill-climbing. 
   2. Description of the Prior Art 
   Increased global demand for vehicular fuel without corresponding increase in available fuel supply has resulted in rising gas prices and the development of vehicles with improved fuel efficiency such as hybrid vehicles which use an internal combustion engine and an electric motor adapted to augment the output of the internal combustion engine when more power is needed. Rechargeable storage batteries on the vehicle energize the electric motor. 
   Hybrid vehicles are complex and expensive to manufacture and maintain due to the need for high amperage capacity batteries and associated control components. One particular disadvantage of hybrid vehicles is that, when the charge of the batteries is exhausted, such as during prolonged uphill climbs, the vehicle suddenly becomes severely under-powered because the electric motor is then unable to supply the needed additional power, and the vehicle has to rely solely on the power supplied by its down-sized engine. Means to solve this problem by reducing or eliminating such dependence on expensive high-capacity batteries would be greatly desirable. 
   It is well known that by simply using a small displacement internal combustion engine in a vehicle instead of its standard engine, the vehicle will gain improved fuel efficiency, but will have poor acceleration performance. The literature states that a standard sedan can be maintained at a cruising speed of 55 MPH using about 8 to 15 horsepower of engine output. The market, however, requires that the vehicle can accelerate from 0 to 60 MPH within 10 to 12 seconds, otherwise the vehicle will not sell. To be marketable, it would need additional power to improve acceleration. For instance a vehicle weighing 2950 lbs. will need about 120 HP to accelerate from zero to 60 MPH within 12 seconds. 
   Other proposed techniques for improving fuel efficiency include use of non-hybrid vehicles having two or more engines. So far, however, this approach has not had significant success in the market mainly due to difficulties in achieving optimum coordination of the engines. 
   Another earlier fuel-saving approach involves means for deactivating some cylinders in a regular internal combustion engine for economical operation when less power is needed, such as when cruising on a level highway, and reactivating them when more power is needed, such as when accelerating or climbing a grade. Fuel savings through this solution, however, has been severely limited, mainly due to power losses associated with the continuing reciprocating motion of the components (pistons, con rods, etc.) within the deactivated cylinders. Means to eliminate such power loss is included in the present invention. 
   A review of the prior art illustrates further shortcomings in providing solutions to the aforesaid problems. 
   U.S. Pat. No. 6,179,098 to Belloso discloses a fuel-efficient and inexpensive automobile having two engines, each coupled to a drive wheel by way of a continuously variable ratio torque converter. Both engines are used for acceleration or hill-climbing. Either engine is then used for economical cruising. One disadvantage of this system is the limited power capacity and speed range of current continuously variable ratio torque converters. 
   U.S. Pat. No. 6,637,283 to Belloso discloses a Control Apparatus for a Continuously Variable Transmission (CVT) which increases its operational speed range, adds reverse functionality and provides means for it to accommodate two separate power sources. However, it does not improve power handling capacity. 
   U.S. Pat. No. 4,439,989 to Yamakawa discloses a system wherein two or more engine units are each coupled to a transmission through an electromagnetic power clutch. The system includes means for operating the engines at a proper phase difference of, preferably 180 degrees to prevent unwanted vibrations. This system is complex and is not readily adaptable for use in automotive vehicles, particularly for the specific purpose of improving fuel efficiency. 
   Other disclosures of wheeled vehicles employing multiple engines or motors are found in U.S. Pat. Nos. 4,481,841; 4,306,630; 4,475,611; 5,253,724; and 5,429,543. 
   U.S. Pat. No. 2,462,902 to Rockwell, et. al., discloses a vehicle with a main engine that drives the rear axle and a booster engine that drives the front axle. The main engine is associated with a power train having a clutch, speed change transmission, propeller shaft, two-speed rear axle drive gear, and a differential. The booster engine has a power train consisting of a clutch, speed change transmission, propeller shaft, disengageable rear drive, and differential. Although the dual engines of Rockwell, et. al., provide some versatility of operation, particularly when the main engine is overloaded and requires the added power of the booster engine, the several required power train components increase the cost and weight of the vehicle, and do not necessarily improve fuel efficiency. 
   U.S. Pat. No. 4,697,660 to Wu, et. al., discloses a vehicle powered by an internal combustion engine and an electric motor. A torque converter is disposed between the output shafts of the engine and motor. A transmission is disposed on the output shaft of the motor adjacent to a solenoid clutch. The vehicle may be powered by the engine or the motor, or by both for increased power. Electricity to energize the motor is supplied by rechargeable batteries causing the motor to be unable to provide power when the batteries are discharged during heavy duty operations. This patent does not eliminate the need for high-capacity batteries, and it does not teach use of more than one internal combustion engine in the vehicle. 
   U.S. Pat. No. 6,594,998 to Bogucki discloses a system combining independent, initially separate internal combustion engines wherein engines not immediately required for power are shut down and disconnected from the running engine(s) and drive train, to reduce fuel consumption. A microprocessor determines vehicle power requirements from engine sensors, and hydraulic pistons controlled by the microprocessor bring the engine units into and out of engagement with each other. Friction plates and locking pins are provided for coupling the crankshafts at predetermined relative angular positions. The need to bring the crankshafts to predetermined angular positions relative to each other so that locking pins can be used to couple the crankshafts to each other makes this system extremely complicated and prone to failure. This is further complicated by engine mount modifications to permit some engine units to be moved closer to other engine units for engagement and away from said units for disengagement, thereby increasing further the chances of failure. 
   U.S. Pat. No. 6,878,092 to Schustek, et. al., discloses a drive arrangement for at least one auxiliary system of a vehicle having an internal combustion engine. It provides at least one supplementary motor and a planetary gear operative between the engine and motor. The auxiliary system may be a climate control compressor. Such arrangement does not provide power to propel the vehicle, and is not useful for improving the overall fuel efficiency of the vehicle. 
   None of the aforesaid disclosures provide a simple and cost-effective way to improve the fuel efficiency of automotive vehicles, particularly for long distance travel on the highways. As previously discussed, the hybrid system has proved complex and expensive, especially because it requires high-capacity, high voltage batteries. 
   It is accordingly a primary object of this invention to provide means for improving the fuel efficiency of automotive vehicles without the need for high-capacity batteries. 
   It is a specific object of the present invention to use power generated by an on-board auxiliary accelerator engine for acceleration and hill-climbing, etc., instead of relying on power stored in high-capacity batteries. 
   It is another object of this invention to provide simple, automatic and reliable means for combining the power of said auxiliary accelerator engine with the power of a primary cruiser engine for acceleration and hill-climbing, etc., and then selectively using the power of said primary engine for economical long distance cruising on the highway. 
   It is also an object of the present invention to use off-the-shelf coupling means of proven reliability to couple said accelerator engine with said primary engine for increased vehicle power, and to decouple said engines for traveling economically based upon said primary engine. 
   It is a further object of this invention to provide add-on modification means for improving the fuel efficiency of existing motor vehicles. 
   It is an additional object of the present invention to provide means to modify an existing motor vehicle into an improved hybrid vehicle that does not require the use of expensive high-capacity batteries. 
   These objects and other objects and advantages of the invention will be apparent from the following description. 
   SUMMARY OF THE INVENTION 
   Whereas hybrid vehicles use an electric motor to provide additional power when needed to augment the power of a primary engine, the vehicle of the present invention instead employs an auxiliary internal combustion “accelerator” engine to provide said additional power. It uses both engines to accelerate and climb hills, etc., and uses only the primary engine for cruising economically. 
   The above and other beneficial objects and advantages are accomplished in accordance with the present invention by an automotive vehicle having power train means comprising:
     a) a primary internal combustion engine of smaller size and better fuel efficiency than the usual engine currently installed in motor vehicles of similar size and weight, said primary engine having sufficient power to maintain said vehicle at an acceptable cruising speed,   b) an auxiliary accelerator internal combustion engine having an output shaft,   c) a high-capacity crankshaft in said primary engine, said crankshaft designed to withstand additional torque from said auxiliary engine in addition to the torque produced by said primary engine, said crankshaft having front and rear ends,   d) coupling means releasibly interactive between the output shaft of said auxiliary engine and the front end of said crankshaft, and   e) speed change transmission means associated with the rear end of said crankshaft, whereby   f) power from said auxiliary engine may be selectively conveyed to said crankshaft to supply additional power for accelerating said vehicle to cruising speed, and   g) after the vehicle reaches cruising speed, the accelerator engine is disengaged from said crankshaft and throttled down or stopped altogether to conserve fuel, thereby   h) enabling said vehicle to travel at cruising speed with reduced fuel consumption on power provided by said primary engine alone, and   i) enabling said auxiliary accelerator engine to remain ready to be reactivated whenever increased power is needed.   

   Said suitable coupling means may be a centrifugal clutch, a fluid torque converter, a CVT torque converter with movable sheaves, a cone clutch, a plate clutch, an electromagnetic power clutch, a sprag clutch or other types of releasable couplings, or combinations thereof. 

   
     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 it is read in conjunction with the following drawings in which: 
       FIG. 1  is a schematic top view of an embodiment of the fuel-efficient vehicle of the present invention. 
       FIG. 2  is a schematic top view of a first alternative embodiment of the fuel-efficient vehicle of the present invention. 
       FIG. 3  is a schematic top view of a second alternative embodiment of the fuel-efficient vehicle of the present invention. 
       FIG. 4  is a schematic top view of a third alternative embodiment of the fuel-efficient vehicle of the present invention. 
       FIG. 5  is a schematic top view of a fourth alternative embodiment of the fuel-efficient vehicle of the present invention. 
       FIG. 6  is a schematic top view of a fifth alternative embodiment of the fuel-efficient vehicle of the present invention. 
       FIG. 7  is a schematic top view of a sixth alternative embodiment of the fuel-efficient vehicle of the present invention. 
   

   For clarity of illustration, details which are not relevant to the invention, such as engine mounts, transmission mounts, undercarriage of the vehicle, and most details of the internal parts of the speed change transmission, differential and transaxle, etc., have been omitted from the aforesaid drawings. 
   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to the drawings wherein one character designates one part of the vehicle,  FIG. 1  shows the vehicular chassis  11  connected to front bumper  12  and rear bumper  13 , and supported by paired front wheels  14  and rear wheels  15 . 
   A power train is shown comprised of primary “cruiser” engine  16  mounted on chassis  11  and coupled to an automatic or manual transmission  17  whose output shaft  18  is coupled to propeller shaft  19  through front universal joint  20 . Propeller shaft  19  is coupled through rear universal joint  21  to pinion  22  of differential  23  which drives the driving (rear) wheels  15 . 
   Although the power train so far described for the embodiment of  FIG. 1  appears to resemble the power train of a standard front engine, rear wheel drive vehicle, in this invention it is modified in three specific ways, namely: a) primary engine  16  is of down-sized capacity to produce only enough power to maintain the vehicle at a satisfactory cruising speed with maximum fuel economy, b) it has a crankshaft  25   a  which is strong enough to withstand the power of both primary engine  16  and an accelerator engine  24 , and c) the front end  25  of crankshaft  25   a  is especially adapted to receive power from accelerator engine  24  through suitable coupling means  26   a.    
   Said coupling means is an assembly which includes centrifugal clutch  26  fixedly mounted on output shaft  27  of accelerator engine  24  and connected through endless chain  28  and sprocket  29  to the front end  25  of crankshaft  25   a . Centrifugal clutch  26  is calibrated to automatically engage when accelerator engine  24  runs above a pre-selected “engagement speed” such as 1200. RPM, and to automatically disengage when accelerator engine  24  runs below said engagement speed or is stopped. The accelerator engine  24  size is selected so that its power, combined with the power of primary engine  16  will be enough to give the vehicle a satisfactory acceleration rate and performance. 
   Primary engine  16  and accelerator engine  24  are controlled by separate gas pedals conventionally located in the vehicle body adjacent the steering column. Both pedals may be placed side by side so that the operator may easily choose to depress both pedals together with his foot, or may selectively depress only the gas pedal of primary engine  16  for economical operation while in cruising mode. Additionally, a separate ignition switch and starter switch may be provided for accelerator engine  24  so that the accelerator engine may be stopped altogether while cruising for further fuel economy, and restarted as needed to supply additional power. 
   To start the vehicle, both engines are started. If the vehicle has automatic transmission, the transmission is shifted to “drive” in the usual manner, and both gas pedals are depressed to urge the vehicle forward in the usual manner, using power from both engines  16  and  24 . Since both gas pedals are depressed at the same time, both engines are accelerated. In particular, accelerator engine  24  is accelerated above the engagement speed to cause centrifugal clutch  26  to be engaged and to transmit power through chain  28 , sprocket  29  and crankshaft  25   a  to augment power from engine  16  and transmit their combined power to transmission  17  to accelerate the vehicle. 
   After the vehicle reaches cruising speed, the gas pedal for accelerator engine  24  is released, and engine  24  is throttled down to idle speed to save fuel, while the vehicle is maintained at its cruising speed by power from primary engine  16  alone. When more power is needed, the operator simply depresses both gas pedals again. When cruising for long distances, accelerator engine  24  may be stopped for more fuel savings, and restarted as necessary. 
     FIG. 2  shows primary engine  30  mounted on chassis  31  and connected to speed change transmission  32  whose output shaft  33  is connected to propeller shaft  34  by front universal joint  35 . Propeller shaft  34  is connected to pinion  36  via rear universal joint  37  to drive rear wheels  38  by way of differential  39 . 
   A coupling means assembly  40   a  includes CVT drive pulley  40  fixedly mounted on output shaft  41  of accelerator engine  42  and connected to CVT-driven pulley  43  by drive belt  44 . Pulley  43  is fixedly mounted on jack shaft  45  which is rotatively mounted on bearings  46 . The inner race of overrunning sprag clutch  47  is fixedly mounted on jack shaft  45  and rotates with it, and the outer race of sprag clutch  47  is connected through endless chain  48  and sprockets  49  to the front end  50  of the crankshaft of primary engine  30 . 
   To operate the vehicle, both primary engine  30  and accelerator engine  42  are started, and transmission  32  is engaged. The vehicle is urged forwardly in the usual manner by accelerating both engines  30  and  42 . When accelerator engine  42  is speeded up above the pre-set engagement speed, CVT drive pulley  40  engages drive belt  44  to drive pulley  43  which rotates jack shaft  45  and the inner race of sprag clutch  47  in the engagement direction, thereby causing the outer race of sprag clutch  47  to be engaged and rotate as a unit with jack shaft  45 . Power from accelerator engine  42  is accordingly transmitted via CVT torque converter  40  through jack shaft  45  and sprag clutch  47  to crankshaft  50  by means of endless chain  48  and sprockets  49 . This combines the power of accelerator engine  42  and primary engine  30  to drive transmission  32 , propeller shaft  34 , differential  39  and drive wheels  38 . 
   After the vehicle reaches cruising speed, accelerator engine  42  is throttled down to idle speed and the vehicle is maintained at cruising speed economically by power from primary engine  30  alone. Meanwhile, since primary engine  30  will be running faster than accelerator engine  42 , the sprag clutch will automatically disengage its outer race from the inner race, placing the outer race in a free-wheeling state so that accelerator engine  42  will not cause a drag on primary engine  30 , particularly if the CVT torque converter drive pulley  40  is not fully disengaged from drive belt  44 . For further fuel economy, accelerator engine  42  may be stopped altogether while cruising, and can remain ready to be restarted, speeded up, and automatically engaged whenever more power is needed. 
   The CVT torque converter can multiply the torque of the accelerator engine  42  up to five times, a feature which may be used to improve acceleration performance, or used to reduce the size and weight of the accelerator engine itself without sacrificing acceleration performance. 
   In  FIG. 3 , primary engine  51  transmits power to drive wheels  52  via transmission  53 , propeller shaft  54  and differential  55  in the conventional manner. Accelerator engine  56  is coupled to a fluid torque converter  57  which is connected to the outer (driver) race  59  of sprag clutch  58  whose inner (driven) race  60  is mounted on the front end  61  of the crankshaft of primary engine  51 . Accelerator engine  56  and primary engine  51  are mounted in coaxial alignment. Sprag clutch  58  is mounted so that it automatically engages when accelerator engine  56  exceeds the speed of primary engine  51 , and automatically disengages when accelerator engine  56  runs slower than primary engine  51 . The fluid torque converter  57  allows variations in the speed and power of accelerator engine  56  relative to the primary engine  51 , and for smoother engagement and disengagement of the two power sources. 
   To operate the vehicle, both engines  51  and  56  are started, the transmission  53  is engaged and both engines are accelerated to urge the vehicle forward in the usual manner. To cruise economically after the vehicle reaches cruising speed, accelerator engine  56  is simply throttled down or stopped altogether. To accelerate or climb hills, accelerator engine is restarted and speeded up as needed. 
   In  FIG. 4 , primary engine  81  is mated to transmission  62 , propeller shaft  63 , differential  64  and drive wheels  65  in the conventional manner. The output shaft  66  of accelerator engine  67  is directly coupled to the outer (drive) race  68  of sprag clutch  69  whose inner (driven) race  70  is fixedly mounted on the front end  71  of the crankshaft of primary engine  81 . This arrangement eliminates the use of a torque converter and yet permits automatic coupling of accelerator engine  67  to primary engine  81  for acceleration and automatic de-coupling of said engines for economical cruising. 
   To operate the vehicle, both engines  81  and  67  are started, then the transmission is engaged and both engines are speeded up to urge the vehicle forward in the usual manner. After the vehicle reaches cruising speed, accelerator engine  67  is throttled down or stopped altogether to save fuel and cruise economically on power from primary engine  81  alone. When more power is needed, accelerator engine  67  is simply restarted and/or speeded up, and sprag clutch  69  will automatically couple it to primary engine  81  to add power as needed. 
   In  FIG. 5 , primary engine  72  is mated to transmission  73 , propeller shaft  74 , differential  75  and drive wheels  76  in the usual manner. The output shaft  77  of accelerator engine  78  is coupled to electromagnetic power clutch  79 , thence to front end  80  of the crankshaft of primary engine  72 . 
   To operate the vehicle, both engines  72  and  78  are started, the transmission  73  engaged, electromagnetic power clutch  79  is engaged and both engines are speeded up to urge the vehicle forward in the usual manner. After the vehicle reaches cruising speed, electromagnetic power clutch  79  is disengaged and at the same time accelerator engine  78  is throttled down or stopped altogether to save fuel. When more power is needed, the accelerator engine is simply restarted and/or speeded up, and at the same time electromagnetic power clutch  79  is engaged to provide added power as needed. 
   In  FIG. 6 , primary engine  85  is mated to transmission  86 , propeller shaft  87 , differential  88  and drive wheels  89 . Accelerator engine  90  is coupled to generator  91  which supplies power to battery  92  and electric motor/generator  93  whose output shaft  94  is integral with the forward extension of the crankshaft of primary engine  85 . In the motor mode, motor/generator  93  can be powered by both generator  91  and battery  92 . In the generator mode, regenerative braking can supply electricity to charge battery  92 . Said generator  91 , and motor/generator  93  represent additional components of a coupling means assembly for producing the sought interaction between the two engines. 
   To operate the vehicle, primary engine  85  is started and transmission  86  is engaged. Primary engine  85  is then speeded up to urge the vehicle forward in the usual, manner. To permit the vehicle to accelerate faster, increasing amount of current from battery  92  is fed into motor/generator  93 , which is placed in the motor mode, to produce supplemental power to assist primary engine  85  in moving the vehicle forward in a faster rate of acceleration. The flow of current from battery  92  can be controlled by a rheostat which is controlled by a rheostat pedal placed alongside the gas pedal. This allows the operator to produce increasing amount of power from both the primary engine  85  and electric motor  93  by simply depressing both pedals simultaneously. After cruising speed is attained, the operator may then elect to travel economically on power from the primary engine  85  alone by simply releasing the rheostat pedal. 
   Auxiliary accelerator engine  90  may be programmed to be automatically started whenever battery  92  is discharged to a predetermined degree so that the battery  92  will be kept constantly fully charged by generator  91 . The power output of accelerator engine  90 , and the generating capacity of generator  91  is adjusted so that they are able to keep pace with the power requirement of motor  93  even when motor  93  is operated steadily at peak capacity. This assures that the vehicle can be operated at peak power capacity (peak combined power of the primary engine  85  and motor  93 ) for prolonged periods, such as during prolonged uphill climbs. This is an improvement over prior hybrid vehicles which lose power when the batteries are discharged. Additionally, since the charge in battery  92  is constantly replenished by generator  91 , battery  92  need not be of very high capacity. Less expensive 12 volt lead-acid batteries may prove adequate and practicable. 
   This embodiment has the added advantage of further improving fuel economy through regenerative braking. This is done by means of automatically reversing the polarity of motor/generator  93  to place it in generator mode whenever the brake pedal is depressed while keeping the transmission engaged so that the momentum of the vehicle will spin the crankshaft of primary engine  85  and the armature of generator  93  to generate electricity to charge battery  92 , a system that is well known in the art. 
     FIG. 7  illustrates how this invention may be retrofitted into an existing vehicle. In this embodiment, the vehicle&#39;s original power train includes a primary four-cylinder engine  95 , transmission  96 , propeller shaft  97 , differential  98  and wheels  99 . Accelerator engine  100  drives generator  101  which charges battery  102  and also supplies power to motor/generator  103  fixedly connected to the front end of the crankshaft of engine  95 . The original primary engine  95  is modified by removing the pistons and connecting rods and other associated moving parts in the front cylinder  105  and rear cylinder  106  and shutting off the air supply and fuel supply to these two cylinders  105  and  106 . The engine is now effectively down-sized to a two-cylinder engine operating on the remaining cylinders  107  and  108 . This method of deactivating half the cylinders in an engine for economical operation, such as for cruising, is an improvement over the prior art which simply deprives the deactivated cylinders of fuel without removing the pistons and con rods whose continued reciprocating motion produces internal and frictional drag to sap the power of the remaining functioning cylinders. 
   As in the embodiment of  FIG. 6 , generator  101  and motor generator  103  represent components of a coupling means assembly for producing the sought interaction between the two engines. 
   To operate the vehicle, the regular engine  95  is started and transmission  96  is engaged. Engine  95  is speeded up to urge the vehicle forward in the usual manner. To permit the vehicle to accelerate faster increasing amount of electric current from battery  102  is fed to motor/generator  103 , which is placed in the motor mode, to produce supplemental power to assist engine  95  in moving the vehicle forward in a faster rate of acceleration. The flow of current to motor/generator  103  is controlled by a rheostat which is operated through a rheostat pedal placed alongside the gas pedal. By depressing both pedals simultaneously the operator can accelerate the vehicle on power from both engine  95  and electric motor  103 . To cruise economically he simply releases the rheostat pedal and operates the vehicle on power from engine  95 . For passing or hill-climbing he simply depresses both pedals together, as needed. 
   Accelerator engine  100  may be programmed to start and stop as needed to keep battery  102  fully charged at all times, and the brake system modified to employ motor/generator  103  for regenerative braking as described above. 
   Although  FIG. 7  illustrates a vehicle with a four-cylinder engine, the same method of down-sizing the existing engine may be used to similarly down-size a six-cylinder engine or an eight-cylinder engine, in a process which will be easily performed by persons skilled in the art. 
   Although specific types of clutches have been illustrated and described as components of the coupling means, other suitable types of clutches, releasable couplings and torque converters may be used, such as dry plate clutches, cone clutches and toroidal torque converters. Furthermore any of these clutches may be designed to be automatically actuated using load and speed sensors in association with programmed computerized vehicle management systems. 
   Although the preferred embodiments are described in great detail, it is to be understood that various changes and modifications may be made therein without departing from the scope of the invention as defined in the appended claims.