Abstract:
An automotive vehicle having improved fuel economy is equipped with a drive system having a primary internal combustion engine and an auxiliary internal combustion engine of smaller size and better fuel economy than the primary engine. The primary engine is adapted to take the vehicle to its cruising speed, at which point the auxiliary engine is activated and interacts by way of an automatic clutch system to power the vehicle while the primary engine is disconnected from the drive system and throttled down.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention concerns fuel-efficient vehicles, and more particularly relates to automobiles having multiple power sources which are continuously interactive in a manner to serve the operational needs of the automobile in acceleration, cruising and hill-climbing. 
   2. Description of the Prior Art 
   Considerable attention has been directed in recent years toward the development of “hybrid” vehicles having improved fuel efficiency. Such hybrid vehicles generally have an internal combustion engine, and an electric motor adapted to augment the output of the internal combustion when additional power is needed. Re-chargeable storage batteries on the vehicle energize the electric motor. 
   The hybrid vehicles generally require severe down-sizing of the internal combustion engine to achieve the sought fuel efficiency for cruising operation, namely travel of the vehicle at substantially constant speed on a reasonably non-hilly road. The batteries must be of high amperage capacity with associated control components in order to adequately power the motor. Such requirements result in high initial cost and high maintenance costs as well as problems related to availability of repair and other services. These added costs are often not fully offset by the savings attributable to fuel efficiency. For instance, the additional cost of the batteries alone is often not yet fully offset by the savings in fuel costs before these expensive batteries reach the end of their useful life and would need to be replaced. Non-hybrid fuel-efficient vehicles also have problematic balances between operating costs and purchase price. 
   U.S. Pat. No. 6,179,078 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, then either engine is used for economical cruising. One disadvantage of this system is the limited power capacity and speed range of current continuously variable ratio torque converters, especially when used for acceleration and hill-climbing. 
   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. It does not improve its 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 particular 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 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. 
   None of the aforesaid disclosures provide a simpler and more cost-effective way to improve the fuel efficiency of automotive vehicles, particularly for long distance travel on the highways. 
   It is accordingly a primary object of this invention to provide a simple mechanical alternative to the complex and expensive hybrid system as means for improving the fuel efficiency of automotive vehicles. 
   It is another object of the present invention to provide a fuel-efficient vehicle through maximal use of the existing power train of current motor vehicles and making only those changes that are minimally necessary to permit the vehicle to travel economically at cruising speeds over long distances. 
   Yet another object of this invention is to provide a fuel-efficient vehicle of the aforesaid nature employing a minimum of modifications of the power train and integral structure of current motor vehicles, so that the invention can be employed not only in the manufacture of new vehicles, but can also be offered as after-market “add-on” modification of existing motor vehicles. 
   These objects and other objects and advantages of the invention will be apparent from the following description. 
   SUMMARY OF THE INVENTION 
   The fundamental feature of this invention is the reversal of the roles played by the primary engine and the auxiliary engine. Whereas in the prior art the primary engine is generally used for long distance travel and has, therefore, to be downsized for fuel-efficiency, and whereas the auxiliary engine is generally used to provide additional power for acceleration and hill-climbing, etc., in this invention their roles are reversed. Thus, in this invention the primary engine is mostly used only for acceleration and hill-climbing, etc., and the auxiliary engine is used mainly to maintain the vehicle at optimum cruising speeds in order to travel economically over long distances on the highway. As a result, the primary engine and power train can remain essentially intact, and the auxiliary engine can be of any desired size and power to provide the vehicle with the most satisfactory balance of fuel economy and performance, particularly for long distance cruising. In the most simple embodiment, the auxiliary engine need not even be equipped with a speed change transmission. 
   The above and other beneficial objects and advantages are accomplished in accordance with the present invention by an improved automotive vehicle having a chassis, a car body mounted on said chassis, vehicle control means within said car body, power train means consisting of a primary engine, speed change transmission, propeller shaft and differential, front and rear wheels, suspension means and steering means, the improvement comprising:
     a) an auxiliary internal combustion engine of smaller size and better fuel efficiency than said primary engine, yet having sufficient power to maintain the vehicle at an acceptable cruising speed,   b) a power output shaft associated with said auxiliary engine, clutch means interactive with said power output shaft, and a power take-off shaft associated with said clutch means, and   c) power transfer means for transferring power laterally between said power take-off shaft and said differential, whereby   d) power from said auxiliary engine may be selectively conveyed to said take-off shaft, thence to said power transfer means and to said differential,   e) said conveyance of power occurring after said vehicle has been accelerated to cruising speed by said primary engine, and said speed change transmission means is shifted to “neutral” to disengage said primary engine from said differential, thereby placing the vehicle in a free wheeling state, after which   f) said auxiliary engine is accelerated to operational speeds, thereby automatically causing engagement of said clutch means and transfer of power to said differential, thus achieving two desirable results, namely:   g) enabling said auxiliary engine to maintain the vehicle at cruising speed with reduced fuel consumption per unit of distance traveled, and   h) enabling the power train means including said primary engine to remain ready to be activated whenever increased power is needed.   

   Said clutch means is a releasable coupling means such as a frictional clutch, centrifugal clutch or continuously variable torque converter. Said power transfer means may be an endless chain connected to sprockets, or spur gears, or combinations thereof. An over-riding sprag clutch may optionally be disposed between said take-off 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 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 magnified partially cutaway view of a portion of the embodiment shown in  FIG. 5 . 
       FIG. 7  is a schematic top view of a fifth alternative embodiment of the fuel-efficient vehicle of the present invention. 
       FIG. 8  is a schematic top view of a sixth alternative embodiment of the fuel-efficient vehicle of the present invention. 
       FIG. 9  is a schematic top view of a seventh 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 EMBODIMENTS 
   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 . 
   Primary engine  16  is mounted on chassis  11  and coupled to speed change transmission  17  whose output shaft  18  is connected through front universal joint  19  to propeller shaft  20  which is connected through rear universal joint  21  to pinion drive  22  to differential  23 . Transmission  17  is either manual or automatic, and is of the type that can be shifted to “neutral” while the vehicle is in motion. Differential  23  drives the rear wheels  15 . Thus far this vehicle may be described as a standard front engine, rear wheel drive vehicle capable of satisfactory performance, particularly for acceleration and hill climbing. 
   Auxiliary engine  24  is mounted on chassis  11  within the engine compartment of the vehicle. The power output of auxiliary engine  24  is matched to the size and weight of the vehicle so that said engine  24  is capable of maintaining the vehicle at optimum cruising speeds on the highways while it is operated at maximum thermal efficiency, i.e., at speeds where it achieves maximal fuel economy per distance traveled. 
   Clutch means, in the form of continuously variable torque converter drive pulley  25 , is mounted on the output shaft of auxiliary engine  24  and is connected to CVT driven pulley  26  by drive belt  27 . Driven pulley  26  is mounted on front jack shaft  28  which is rotatively mounted on front jack shaft bearing  29  and is connected to a take-off shaft in the form of auxiliary propeller shaft  30  by front auxiliary universal joint  31 . Auxiliary propeller shaft  30  is connected to rear jack shaft  32  by rear auxiliary universal joint  33 . Rear jack shaft  32  is rotatably mounted on rear jack shaft bearing  38 . Rear jack shaft sprocket  34  is fixedly mounted on rear jack shaft  32  and is connected by power transfer means in the form of endless chain  35  to transmission output shaft sprocket  36  which is fixedly mounted on transmission output shaft  18 . 
   In operation, the vehicle is accelerated from a standing start to cruising speed by power from primary engine  16  transmitted through speed change transmission  17 , propeller shaft  20  and differential  23  to driving rear wheels  15 . To cruise economically, transmission  17  is shifted to neutral and the primary engine is reduced to idling speed. Auxiliary engine  24  is accelerated to cruising speed, which automatically engages CVT belt  27  on CVT drive pulley  25 , thereby transmitting power to CVT driven pulley  26 , thence through auxiliary propeller shaft  30  and through sprockets  34  and  36  and endless chain  35  to universal joint  19 , propeller shaft  20 , universal joint  21 , pinion shaft  22  and differential  23  to drive wheels  15 , thereby economically keeping the vehicle at cruising speeds. Whenever more power is needed, transmission  17  is simply shifted to “drive” and engine  16  is accelerated until the increased power is no longer needed, whereupon transmission  17  is again shifted to neutral and the vehicle is again kept at cruising speed using the smaller, more fuel-efficient auxiliary engine  24 . 
     FIG. 2  illustrates an alternative embodiment of the invention showing a vehicular chassis  39  upon which is mounted the standard layout of a front-engine rear-drive vehicle, with primary engine  40 , transmission  41 , front universal joint  42 , propeller shaft  43 , rear universal joint  44 , differential  45 , and rear wheels  46 . Auxiliary engine  47  is mounted at the rear of the vehicle. This facilitates retrofitting it on an existing vehicle. CVT drive pulley  48  is mounted on the output shaft of engine  47 , and is connected to CVT driven pulley  49  by drive belt so. Driven pulley  49  is mounted on rear jack shaft  51  which is rotatably journaled to rear jack shaft bearing  52  and connected to auxiliary propeller shaft  53  by rear auxiliary universal joint  54 . Auxiliary propeller shaft  53  is a two-part splined shaft to permit a degree of variation of its length to adjust for the movement of the differential  45  while the vehicle is in operation. 
   Auxiliary propeller shaft  53  is connected to front auxiliary jack shaft  55  by front auxiliary universal joint  56 . Front jack shaft  55  is rotatably journaled to front jack shaft bearing  57  which is fixedly mounted on differential  45 . Front jack shaft sprocket  58  is fixedly mounted on front jack shaft  55  and is connected to pinion drive sprocket  59  through drive chain  61 . Pinion drive sprocket  59  is fixedly mounted on pinion drive shaft  60  of differential  45 . 
   The vehicle is accelerated from a standing start by power from primary engine  40  which is transmitted through transmission  41 , propeller shaft  43 , pinion drive  60 , and differential  45  to the wheels  46 . Upon reaching the desired cruising speed, the transmission  41  is shifted to “neutral” and then engine  47  is speeded up to automatically engage torque converter belt  50  to CVT drive pulley  48  and transmit power to CVT driven pulley  49 , thence through rear jack shaft  51  to auxiliary propeller shaft  53  and front jack shaft  55 . Power is then transmitted further from front jack shaft  55  through sprockets  58  and  59  and chain  61  to pinion drive  60 , differential  45  and wheels  46 . The vehicle is now able to cruise economically on power from auxiliary engine  47 . 
     FIG. 3  illustrates a second alternative embodiment of the invention when used on a front wheel drive vehicle. Primary engine  62  is mounted on chassis  63  and is connected through transaxle  64  to front drive wheels  65  via universal joints  66  and drive shafts  67  in the conventional manner. A transaxle is a combination of two distinct parts coupled together and housed in an integrated casing, the transaxle casing. These parts are: 1) a speed change transmission, and 2) a differential. 
   Auxiliary engine  68  is mounted at the rear of the vehicle and is connected via CVT drive pulley  69 , CVT drive belt  70 , CVT driven pulley  71 , rear jack shaft  72 , propeller shaft  73 , front jack shaft  74 , drive sprocket  75 , drive chain  76 , driven sprocket  77  and pinion drive shaft  78  to rear differential  79 , which drives the drive wheels  80 . 
   Power for acceleration and hill climbing, etc., is taken from primary engine  62  and coursed through transaxle  64  to front drive wheels in the usual manner. To cruise economically, transaxle  64  is shifted to “neutral” and engine  68  is speeded up to automatically engage CVT drive pulley  69  to drive belt  70  and CVT driven pulley  71 . Power is then transmitted from CVT driven pulley  71  to rear jack shaft  72 , thence to propeller shaft  73 , front jack shaft  74 , drive sprocket  75 , drive chain  76 , driven sprocket  77 , pinion drive  78 , differential  79  and rear drive wheels  80 . 
     FIG. 4  illustrates a third alternative embodiment of the invention, showing a different manner of using this invention in a front-engine front-wheel-drive vehicle. Primary engine  81  is connected to front drive wheels  82  via transaxle  83  and drive shafts  84  in the conventional manner. Auxiliary engine  85  is mounted in the front of the vehicle as well, preferably in the same engine compartment as primary engine  81 . This leaves space at the rear of the vehicle for the trunk, etc. 
   The vehicle is accelerated to cruising speed by power from primary engine  81  transmitted through transaxle  83  and drive shafts  84  to front drive wheels  82 . To cruise economically, transaxle  83  is shifted to “neutral” and primary engine  81  is slowed down to idle speed or stopped altogether. Auxiliary engine  85  is then speeded up to engage CVT drive pulley  86  on CVT drive belt  87  and transmit power to CVT driven pulley  88 . CVT driven pulley  88  is fixedly mounted on jack shaft  89  which is journaled on jack shaft bearing  90  and connected via front universal joint  91  to propeller shaft  92 , thence through rear universal joint  93  to pinion drive  94  and differential  95  which drives the rear drive wheels  96 . 
     FIGS. 5 and 6  illustrate a fourth alternative embodiment of the invention, showing how the invention may be employed in a front wheel drive vehicle through a simple modification of the transaxle. In this embodiment, the transaxle  97  is modified by adding an external pinion drive  98  geared to the crown wheel  131  of the differential  132  portion of transaxle  97 . External pinion drive  98  provides a second input port to the differential  132  in addition to the internal pinion drive  134  which transmits power from the speed change transmission portion of transaxle  97  to the differential  132 . 
   To accelerate to cruising speed, power from primary engine  99  is transmitted through the speed change transmission portion of transaxle  97  through internal pinion drive  134  to crown wheel  131  of differential  132  thence to drive shafts  100  to drive wheels  101 . After cruising speed is attained, transaxle  97  is shifted to “neutral” and primary engine  99  is slowed down to idle speed or stopped, to conserve fuel. Auxiliary engine  102  is then speeded up to engage CVT drive pulley  103  to drive belt  104  and driven pulley  105 . Driven pulley  105  is fixedly mounted to jack shaft  106  which is journaled to jack shaft bearing  107  and connected through universal joint  108  to the external pinion drive  98  of transaxle  97  from which power is then transmitted through crown wheel  131  thence through drive shafts  100  to wheels  101 . The vehicle then cruises economically on power from engine  102 . 
     FIG. 7  illustrates a fifth alternative embodiment showing how a differential with two pinion drives may be employed in a front-engine rear wheel drive vehicle with independent rear suspension. Here power from a front-mounted primary engine  135  is transmitted through speed change transmission  136 , front universal joint  137 , propeller shaft  138 , rear universal joint  139  thence through front pinion drive  140  and crown wheel  141  of differential  142  thence through drive shafts  143  to drive wheels—to accelerate the vehicle to cruising speed. Speed change transmission  136  is then shifted to “neutral” and primary engine  135  is slowed to idle speed or stopped to conserve fuel. Auxiliary engine  145  is then speeded up to engage drive pulley  146  on drive belt  147  and driven pulley  148 . Driven pulley  148  is fixedly mounted on jack shaft  149  which is journaled to jack shaft bearing  150  and connected to rear pinion drive  151  through auxiliary universal joint  152 . Power is then transmitted from auxiliary engine  145  to rear pinion drive  151  thence to crown wheel  141  of differential  142  thence to drive shafts  143  and wheels  144  to keep the vehicle at cruising speed, economically. 
     FIG. 8  illustrates how the invention may be employed in a rear-engine rear-drive vehicle with independent rear suspension, using the modified transaxle of the type shown in  FIGS. 5 and 6 . Power from primary engine  167  is transmitted through transaxle  168  to drive axles  109  and drive wheels  110  to accelerate the vehicle to cruising speed. Primary engine  167  is then slowed to idle speed or stopped altogether to conserve fuel. To maintain cruising speed, engine  111  is speeded up to cause CVT drive pulley  112  to engage drive belt  113  and drive driven pulley  114 . Driven pulley  114  is fixedly mounted on jack shaft  115  which is journaled to jack shaft bearing  116 . Jack shaft  115  is connected through universal joint  117  to external pinion drive  118  of transaxle  168 . Thus, the vehicle is maintained at cruising speed economically by power from engine  111  transmitted through drive pulley  112 , drive belt  113 , driven pulley  114 , jack shaft  115 , universal joint  117  and external pinion drive  118  to transaxle  168 , thence to drive shafts  109  and drive wheels  110 . 
   It is an essential feature of this invention that means are provided to prevent the operation or the “engine drag” of one engine from interfering with the operation of the other. Much of this is accomplished through the use of the movable-sheave continuously-variable-ratio torque converter used with the auxiliary engine in all of the above preferred embodiments. One reason for this choice is that this type of automatic transmission automatically disengages whenever the auxiliary engine is running below the “engagement speed.” It therefore remains disengaged while the vehicle is accelerating or climbing, etc., or even going in reverse using the primary engine, during which time the auxiliary engine is presumably running at slow “idle” speed or is not running at all. It only engages when the auxiliary engine is speeded up above the engagement speed to permit the vehicle to travel at cruising speed economically, and during this time the regular transmission is first shifted to “neutral” before the primary engine is slowed down to idle speed or stopped. There is nothing to prevent the driver from using power from both engines while going forward to achieve really fast acceleration. 
   Although all the foregoing embodiments employed movable sheave CVT torque converters to transmit power from the auxiliary engine to the differential powering the drive wheels, the invention is not limited to embodiments using this particular type of releasable coupling. Thus, other types of releasable couplings may be used instead of the CVT torque converter. Other such couplings include dry plate clutches, dog clutches, centrifugal clutches, cone clutches, electromagnetic clutches and others. A particularly preferred clutch means is a sprag clutch, described in some detail in U.S. patent application Ser. No. 11/032,672, and incorporated herein by reference. 
   For example,  FIG. 9  illustrates how a fluid coupling in combination with a sprag clutch may be used in a standard front engine-front wheel drive vehicle. Primary engine  120  transmits power through transaxle  121  and drive shafts  122  to front drive wheels  123  to accelerate the vehicle to cruising speed. Transaxle  121  is then shifted to “neutral” and the primary engine is slowed to idle speed or stopped to conserve fuel. Auxiliary engine  124  is then speeded up to operational speed to transmit power via fluid torque converter  125  thence through sprag clutch  126  to propeller shaft  127  and pinion drive  128  thence to differential  129  and to rear drive wheels  130 , and thus economically maintain the vehicle at cruising speed. The fluid coupling  125  essentially decouples engine  124  from drive wheels  130  while the vehicle is driven (presumably slowly) in reverse; while the sprag clutch  126  remains disengaged while the vehicle is accelerating, etc., using primary engine  120 , and engages only when engine  124  is speeded up to maintain cruising speed, during which time the transaxle  121  is shifted to neutral before the primary engine  120  is slowed down or stopped, as previously stated. 
   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 spirit and scope of the invention which is more fully defined in the appended claims.