Abstract:
A motor vehicle is provided with a power train having primary and auxiliary internal combustion engines which selectively feed power to a jackshaft. The power accumulated in the jackshaft is conveyed to a speed change transmission. Fuel economy is achieved by utilizing only one engine when lesser power is needed by the vehicle.

Description:
PRIOR APPLICATIONS 
     This application is a Continuation-In-Part of application Ser. No. 12/152,943, filed May 20, 2008 now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a vehicle having multiple internal combustion engines whose power output can be combined and routed to a transmission for the purpose of improving fuel efficiency and accommodating the power needs of the vehicle. 
     2. Description of the Prior Art 
     Increasing greenhouse gas emissions to the atmosphere and the escalating cost of fossil fuels have spurred the search for means to improve automotive fuel efficiency. One solution has been the hybrid automobile which uses a small fuel-efficient internal combustion engine augmented by a battery-driven electric motor to power the vehicle. Another solution employs two or more internal combustion engines, using their combined power for acceleration, climbing steep grades, etc., and using the power of one engine to cruise economically. 
     The present invention relates to the latter solution, using two engines for acceleration, and one engine to cruise. 
     Prior dual engine systems have encountered difficulties involving the smooth and efficient interaction of the engines, and the routing of controlling amounts of fuel to the engines. For example, U.S. Pat. No. 4,421,217 to Vagias discloses a vehicle propulsion system involving a small engine employed to propel the vehicle economically in a cruising mode, and a large engine intended to add additional power when needed by the vehicle for acceleration, hill climbing or other power demands. In operation, the small engine, when in a situation where it is struggling to maintain propulsion of the vehicle, is automatically caused to start up the large engine. The start up procedure employs a clutch which unifies the crankshafts of both engines. Such procedure engenders stall-out of the small engine. Also, the integrated crank shafts are unlikely to produce a smooth combined effect because of differences in centrifugal balances and timing factors. Vagias&#39; large engine cannot run independently because it must act through the small engine in order to transmit power to the transmission. This complicates the equitable supply of fuel to either the small engine alone or the integrated engines where both crankshafts rotate in unison. 
     Japanese Patent JP358026635A to Sakazaki discloses a vehicle having separate engines to drive the wheels of front and rear axles. Operator-manipulated individual accelerator pedals enable the operator to activate either or both engines. However, separate speed-change transmissions must be associated with each engine, thereby contributing to the cost and weight of the vehicle. 
     U.S. Pat. No. 6,637,283 to Belloso concerns a control apparatus for a continuously variable transmission, and is capable of accommodating two different power input sources. However, this is not commercially available, and said two power input sources must be received from opposite directions. 
     Accordingly, it is an object of this invention to provide a vehicle equipped with two engines for the purpose of achieving improved fuel efficiency through the use of a speed change transmission of commonplace design. 
     It is another object of the present invention to provide a vehicle of the aforesaid nature wherein the speed of each engine is separately controllable, and the output powers of said engines can be accumulated and fed to a speed change transmission. 
     It is another object of this invention to provide a vehicle of the aforesaid nature wherein the speed of each engine is controlled by adjustable supply of fuel to each engine. 
     These objects and other objects and advantages of the invention will be apparent from the following description. 
     SUMMARY OF THE INVENTION 
     The above and other beneficial objects and advantages are accomplished in accordance with the present invention by a motor vehicle having a chassis elongated upon a center axis between paired front and paired rear wheels, and a power train comprised of:
     a) primary and auxiliary internal combustion engines located one in front of the other adjacent said front wheels, each engine having a power output shaft extending in parallel juxtaposition with said center axis and both having the same direction of rotary motion,   b) separate fuel supply means for each engine,   c) releasible coupling and power transfer means associated with each output shaft,   d) a speed change transmission positioned rearwardly of said engines and having an input shaft, and   e) a jackshaft laterally spaced from said engines in parallel relationship to said center axis, and rotatably secured by said chassis to selectively receive and accumulate power from said engine output shafts and convey said accumulated power to the input shaft of said speed change transmission, whereby   f) economy of operation is achieved by deactivating one engine when lesser power is needed for propulsion of the vehicle.   

     Said releasable coupling and power transfer means may be a movable sheave torque converter unit (CVT) that produces continuously variable output rotational speeds, or may be a fluid torque converter. Still other specific embodiments of the releasible coupling and power transfer means include releasible automatic or manually activated clutches such as a centrifugal clutch, electromagnetic power clutch, cone clutch and friction plate clutch. 
     Said jackshaft may be divided into sections, each section being interactive with a separate engine, with each section releasibly coupled to the next contiguous section byway of a suitable coupling means such as a free wheeling clutch such as a sprag clutch. Such construction serves to ensure more complete decoupling of one engine from the other during low power operations such as when traveling at substantially constant cruising speeds on a highway. 
     The primary engine may be made to have about ½ to ⅓ the size and power capacity of the auxiliary engine to maximize fuel economy while cruising with minimum load, and to maximize performance in acceleration and other heavy duty capacity. Furthermore, each engine may be coupled to the jackshaft via a free-wheeling clutch, such as a sprag clutch, so that it becomes possible to choose to power the vehicle with only the primary engine for light duty operation (e.g., for cruising with minimum load), or with only the auxiliary engine for medium duty operation (e.g., for cruising when fully loaded), and with power from both the primary engine and the auxiliary engine for maximal acceleration or heavy duty operation. 
     In general, an internal combustion engine is most fuel-efficient when it is operated at about 60% to 90% of its rated capacity. It is generally less fuel-efficient when operated outside this range. Furthermore, an automobile weighing about 3000 lbs may need only about 30 horsepower (HP) to maintain cruising speed on the highway, but may need about 120 HP to accelerate within an acceptably short time to keep up with traffic. In a conventional automobile equipped with only one engine, this vehicle would have to be equipped with an engine having a rated capacity of at least 120 HP, yet when it is operated to produce only 30 HP for cruising it would be operating at only 25% of its rated capacity which is too far below the 60% to 90% range of its rated capacity for it to be fuel-efficient. It would be preferable, from the fuel efficiency standpoint, for the vehicle to be powered by a 40 HP engine for cruising, since this engine would then be operating at 75% of its rated capacity, i.e. at the middle of its most fuel efficient range. 
     To permit selective use of either the primary engine or the auxiliary engine, or both, the fuel supply of each engine may be controlled through a separate gas pedal for each engine. Said gas pedals may be most conveniently operated by the operator&#39;s right foot if they are placed next to each other in the usual location of the gas pedal, with their size and position being adjusted so that either pedal may be independently depressed to control the operation of either engine, or both may be depressed together by the right foot to operate both engines at the same time. 
     Alternatively, load sensors associated with the power train may be used to send input data to a vehicle&#39;s power management computer to regulate selective use of either or both engines, as needed, to suit operating conditions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing forming a part of this specification and in which similar numerals of reference indicate corresponding parts in all the figures of the drawing: 
         FIG. 1  is a schematic top view of an embodiment of the vehicle of the present invention. 
         FIG. 2  is a schematic top view of a first alternative embodiment of the vehicle of the present invention. 
         FIG. 3  is a schematic top view of a second alternative embodiment of the vehicle of the present invention. 
         FIG. 4  is a schematic top view of a third alternative embodiment of the 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 internal parts of the transmission and differential, etc., have been omitted from the aforesaid drawings. Furthermore/details of the internal parts of CVT torque converters and sprag clutches, which are well known in the art and readily available in the standard texts on the subjects, are likewise omitted from the aforesaid drawings. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings wherein one character designates one feature of the invention,  FIG. 1  shows a vehicle of the present invention having a chassis  11  connected to front bumper  12  and rear bumper  13  by intervening elongated side portions  99 , and supported by paired front wheels  14  and paired rear wheels  15 . 
     A power train is shown comprised of primary “cruiser” engine  16  mounted on chassis  11 . Primary CVT driver pulley  17  is mounted on output shaft  18  of said primary engine, and is connected to primary CVT driven pulley  19  by drive belt  20 . Driven pulley  19  is fixedly mounted on jackshaft  21  which is rotatably journaled on bearings  22  anchored on side portion  99  of chassis  11 . Jackshaft  21  is connected to input shaft  23  of speed change transmission  24  via chain  25  and sprockets  26 . Power from speed change transmission  24  is conveyed via front universal joint  27 , propeller shaft  28 , rear universal joint  29 , pinion  30 , and differential  31  to the rear wheels  15  to drive the vehicle. 
     The size and power capacity of primary engine  16  is designed to be sufficient to keep the vehicle at cruising speed on a fairly level highway, but small enough so that it can maintain said cruising speed in the most fuel-efficient manner. 
     For heavy duty operation, such as for acceleration, towing, carrying heavy load, or climbing a steep grade, the vehicle is equipped with an auxiliary engine  32  whose size and power capacity is designed so that, when it is operated together with primary engine  16 , their combined power will be sufficient to power the vehicle during said heavy duty operations. 
     Auxiliary CVT drive pulley  33  is mounted on the output shaft  34  of auxiliary engine  32  and is connected to auxiliary driven pulley  35  by auxiliary drive belt  36 . Auxiliary driven pulley  35  is fixedly mounted on jackshaft  21  so that when both primary engine  16  and auxiliary engine  32  are operated at the same time, their combined power is conveyed by jackshaft  21  to speed change transmission  24  thence to said rear wheels. The two engines  16  and  32  are operated together for acceleration and other heavy duty operations. After the vehicle reaches cruising speed, auxiliary engine  32  is throttled down to idle speed or stopped to conserve fuel, and the vehicle is maintained at cruising speed by power from primary engine  16  alone. 
     The CVT torque converter, comprised of drive pulley  33 , drive belt  36  and driven pulley  35 , automatically becomes disengaged when auxiliary engine  32  runs below a minimum “engagement speed” such as when it is stopped or run at idle speed. Accordingly, when the vehicle is traveling at cruising speed, the slowed or stopped auxiliary engine  32  is automatically disengaged from the rest of the power train so that it will not exert a drag on primary engine  16 . If engine  32  runs at idle speed, its power is readily available when needed by simply increasing its fuel supply. If it is stopped, means for it to be quickly restarted to provide auxiliary power may be provided, in a manner similar to current hybrid vehicles. 
     Gas pedal  37  regulates fuel supply to primary engine  16  through fuel line  196 , and gas pedal  38  regulates fuel supply to auxiliary engine  32  through fuel line  197 . The driver, therefore, is able to selectively operate either engine  16  or engine  32  by selectively depressing its corresponding gas pedal,  37  or  38 . To operate both engines  16  and  32  at the same time, he simply depresses both pedals simultaneously. 
       FIG. 2  shows a first alternative embodiment of the vehicle  41  having a chassis  42 , front bumper  43 , rear bumper  44 , front wheels  45  and rear wheels  46 . Primary engine  47  is coupled to a fluid torque converter  48  on whose output shaft  49  is mounted drive sprocket  50 . Jackshaft  51  is mounted alongside primary engine  47  rotatably journaled on bearings  52  which are anchored on chassis  42 . Power from primary engine  47  is transmitted to jackshaft  51  via torque converter  48 , drive sprocket  50 , endless chain  53  and driven sprocket  54  which is fixedly mounted on jackshaft  51 . 
     The size and power capacity of primary engine  47  is selected to be sufficient to maintain the vehicle  41  at cruising speed, and yet be small enough to perform such function in the most fuel-efficient manner. 
     Auxiliary engine  55  is installed in vehicle  41  to provide additional power such as for acceleration and hill climbing. Auxiliary engine  55  is coupled to auxiliary fluid torque converter  56  on whose output shaft  57  is mounted auxiliary drive sprocket  58  which is connected by endless chain  59  to driven sprocket  60  which is fixedly attached to the outer race  61  of sprag clutch  62  whose inner race  63  is fixedly mounted on jackshaft  51 . Jackshaft  51  is connected to speed change transmission  64  via jackshaft drive sprocket  65 , endless chain  66  and driven sprocket  67  which is mounted on input shaft  68  of transmission  64 . 
     The power capacity and size of auxiliary engine  55  is selected so that its power output, when combined with the power output of primary engine  47  will be sufficient to give the vehicle  41  satisfactory performance in acceleration, climbing a grade and other heavy duty operations in which the vehicle is expected to be used. 
     To operate the vehicle, primary engine  47  and auxiliary engine  55  are started and speeded up. Power from primary engine  47  is conveyed via fluid torque converter  48 , thence through chain  53  and sprockets  50  and  54  to jackshaft  51 , thence via chain  66  and sprockets  65  and  67  to speed change transmission  64  which is shifted to “drive” thereby transmitting power to propeller shaft  69  and differential  70  to drive wheels  46 . Additional power from auxiliary engine  55  is conveyed via auxiliary fluid torque converter  56  through chain  59  and sprockets  58  and  60  thence via sprag clutch  62  and jackshaft  51  to chain  66 , sprockets  65  and  67  and transmission  64  to supply additional power to the wheels  46 . 
     After the vehicle  41  reaches cruising speed, auxiliary engine  55  is throttled down to idle speed or stopped altogether to conserve fuel. When auxiliary engine  55  is slowed down or stopped, sprag clutch  62  disengages outer race  61  automatically from inner race  63  thereby decoupling the auxiliary engine  55  completely from jackshaft  51  and preventing the auxiliary engine  55  from exerting a drag force on the vehicle. Vehicle  41  then continues to travel, fuel-efficiently, on power from primary engine  47  alone. 
     Whenever additional power is again needed, the operator simply feeds more fuel to auxiliary engine  55 , speeding it up, which will cause sprag clutch  62  to be automatically engaged, thereby transmitting the additional power to jackshaft  51  to help power the vehicle. 
       FIG. 2  shows auxiliary engine  55  to be substantially larger than primary engine  47 . This is to illustrate that for the purpose of maximizing fuel economy it may be advantageous to downsize the cruiser engine (in this case, primary engine  47 ) to about one-fourth of the total power capacity available to the vehicle. The literature suggests that the average automobile is able to cruise comfortably, on a relatively level highway, using as little as about 25 to 35 horsepower which is approximately one-fourth of the power output of the engine of an average automobile. Conversely, for maximal performance, the power of the auxiliary engine may be selected to be two to four times that of the primary engine. 
     Gas pedal  39  regulates fuel supply to primary engine  47  via fuel line  198  and gas pedal  40  regulates fuel supply to auxiliary engine  55  via fuel line  199 . The operator, therefore, is able to selectively operate either engine  47  or engine  55  by depressing corresponding gas pedals  39  or  40 , respectively. To operate both engines at the same time, he simply depresses both pedals simultaneously with one foot, which is easily done since the pedals are located side by side. 
     A second alternative embodiment, illustrated in  FIG. 3 , shows a vehicle  71  having a chassis  72 , front bumper  73 , rear bumper  74 , front wheels  75 , rear wheels  76 , primary engine  77  and auxiliary engine  78 . A centrifugal clutch  79  is mounted on the output shaft  80  of primary engine  77  and is coupled to jackshaft  81  by endless chain  82  and sprockets  83 . Jackshaft  81  is rotatably mounted on bearings  84 . Auxiliary centrifugal clutch  85  is mounted on the output shaft  86  of auxiliary engine  78 , and is connected to jackshaft  81  by endless chain  87  and sprockets  88 . 
     To operate the vehicle  71 , primary engine  77  and auxiliary engine  78  are started and speeded up. Centrifugal clutch  79  has a preset “engagement speed” and, when the rotational speed of output shaft  80  exceeds the engagement speed, centrifugal clutch  79  automatically engages and transmits power to jackshaft  81  via endless chain  82  and sprockets  83 . Similarly, auxiliary centrifugal clutch  85  has a preset engagement speed, and when the rotational speed of output shaft  86  exceeds this engagement speed the centrifugal clutch  85  automatically engages and transmits power to jackshaft  81  via endless chain  87  and sprockets  88 . Jackshaft  81  then transmits this combined power of the two engines  77  and  78  to transmission  89  via jackshaft sprocket  90 , endless chain  91  and transmission sprocket  92  which is mounted on transmission input shaft  93 . Power from transmission  89  is then conveyed through propeller shaft  94  and differential  95  to drive wheels  76  to propel the vehicle  71 . 
     When vehicle  71  reaches cruising speed, auxiliary engine  78  is slowed down to idle speed (or stopped altogether) to conserve fuel. When the rotational speed of output shaft  86  falls below the engagement speed of centrifugal clutch  85 , centrifugal clutch  85  automatically disengages so that auxiliary engine  78  will not exert any drag on the vehicle. Vehicle  71  then continues traveling economically on power from primary engine  77  alone. 
     When additional power is needed such as for accelerating to pass another vehicle, or to climb a grade, auxiliary engine  78  is simply speeded up to be re-engaged automatically via centrifugal clutch  85 , or, if it had been stopped, it is then restarted and speeded up to supply additional power as needed. 
     Although a centrifugal clutch is shown in this embodiment, other types of clutches can be used, such as an electromagnetic clutch, friction clutch, or toroidal torque converter. 
     Gas pedal  96  regulates fuel supply to primary engine  77 , and gas pedal  97  regulates fuel supply to auxiliary engine  78 . The operator, therefore, may selectively operate either engine  77  or engine  78  by selectively depressing its corresponding gas pedal,  96  or  97 . To operate both engines at the same time he simply depresses both pedals simultaneously. 
       FIG. 4  shows how additional alternative embodiments may be made by combining certain features of any of the foregoing embodiments with selected features of another. The embodiment shown in  FIG. 4  comprises a vehicle  131  having a chassis  132 , front bumper  133 , rear bumper  134 , front wheels  135 , rear wheels  136 , primary engine  137  and auxiliary engine  138 . CVT drive pulley  139  is mounted on output shaft  140  of primary engine  137  and is connected to CVT driven pulley  141  by drive belt  142 . CVT driven pulley  141  is mounted on jackshaft  143  comprised of two halves coupled by speed activated clutch  144 . Jackshaft  143  is connected to input shaft  145  of speed change transmission  146  via endless chain  147  and sprockets  148 . Power from speed change transmission  146  is conveyed to rear wheels  136  via propeller shaft  149  and differential  150 . 
     Auxiliary engine  138  is coupled to fluid torque converter  151  via torque converter sprocket  152 , endless chain  153  and sprag clutch sprocket  154  which is fixedly mounted on the outer race  155  of sprag clutch  156  whose inner race  157  is fixedly mounted on jackshaft  143 . Sprag clutch  156  is a freewheeling clutch whose outer race  155  automatically engages (and drives) the inner race  157  whenever the rate of rotation of the outer race  155  exceeds that of inner race  157 , and automatically disengages when the rate of rotation of outer race  155  is less than that of inner race  157 . 
     To operate vehicle  131 , primary engine  137  and auxiliary engine  138  are started and speeded up. When the rate of rotation of primary engine output shaft  140  exceeds the engagement speed of CVT drive pulley  139 , drive pulley  139  engages and drives driven pulley  141  via drive belt  142  which turns jackshaft  143 . Power from auxiliary engine  138  is conveyed to said jackshaft via torque converter  151 , sprocket  152 , endless chain  153 , sprag clutch sprocket  154  and sprag clutch outer race  155  which causes sprag clutch  156  to engage and cause inner race  157  to turn jackshaft  143 , thus combining the power of auxiliary engine  138  with that of primary engine  137  to turn said jackshaft. 
     Power from jackshaft  143  is then conveyed to speed change transmission  146  via endless chain  147  and sprockets  148 , and the power is in turn transmitted via transmission  146 , propeller shaft  149 , and differential  150  to rear wheels  136  to drive the vehicle  131 . After the vehicle  131  reaches cruising speed, the auxiliary engine may be throttled down to idle speed or stopped altogether to conserve fuel. When the speed of auxiliary engine  138  falls below that of primary engine  137 , sprag clutch  156  automatically disengages so that neither auxiliary engine  138  or associated torque converter  151  can exert drag on jackshaft  143 . The vehicle  131  will then continue to travel fuel-efficiently on power from primary engine  137  alone. 
     Fuel supply to primary engine  137  is regulated through gas pedal  158 , and fuel supply to auxiliary engine  138  is regulated through gas pedal  159  which is located alongside gas pedal  158  so that the operator may conveniently depress either pedal singly or depress both pedals at the same time with one foot. He may then easily elect to operate both engines for maximal power, or operate only said primary engine for maximal fuel economy. It should be noted that whenever primary engine  137  slows down below the engagement speed of CVT drive pulley  139 , the associated CVT torque converter automatically disengages. 
     Other embodiments of the invention may be made by using different combinations of clutches and torque converters to connect the primary and the auxiliary engines to the jackshaft, such as by using an electromagnetic power clutch or a centrifugal clutch to connect either engine to the jackshaft in combination with a CVT torque converter or a fluid torque converter for the other engine, or even the combination of an electric generator with associated electric motor. 
     Although preferred embodiments are described in detail, it is to be understood that various changes and modifications may be made therein without departing from the scope of the invention as described in the appended claims.