Abstract:
A hybrid power system for a vehicle which may include an internal combustion engine and a supplemental energy system for converting the mechanical energy generated by the engine to electrical energy and storing it as opportunity provides; and using the stored electrical energy to augment engine output as necessary. The supplemental energy system may include a motor-generator engaged with a flywheel.

Description:
FIELD OF THE INVENTION 
     This invention relates to hybrid vehicles and, in particular, hybrid vehicles having removable supplemental electrical power sources. 
     BACKGROUND OF THE INVENTION 
     Hybrid work vehicles are becoming more and more prevalent in today&#39;s world as such vehicles tend to have significantly improved fuel efficiencies. However, the improved fuel efficiencies must be weighed against other less positive factors. For example, hybrid vehicles tend to be significantly more complex and expensive than non-hybrid vehicles. Moreover, available work vehicles on the market tend to be all or nothing choices, i.e., they are either hybrid vehicles or non-hybrid vehicles. Some users may want hybrid vehicles under certain circumstances and non-hybrid under other circumstances. 
     SUMMARY OF THE INVENTION 
     A system and method are presented for achieving a hybrid drive as an option on a work vehicle. The inventors demonstrate now to accomplish this by, for example, hybridizing the work vehicle via mechanical connection of a motor-generator to the flywheel ring gear of the vehicle using an access hole in the bell housing normally reserved for a starter and adding motor-generator control software to the vehicle&#39;s engine controller. Such an arrangement tends to reduce or minimize interference with other equipment on the vehicle, i.e., tends to favorably address space constraints on work vehicles. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an exemplary work vehicle utilizing the invention; 
         FIG. 2  illustrates a schematic for an exemplary embodiment of the invention; 
         FIG. 3  illustrates an exemplary mounting flange on which the motor-generator may be attached; and 
         FIG. 4  illustrates a schematic for an alternative exemplary embodiment of the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  illustrates an exemplary work vehicle which may benefit from the invention. The vehicle illustrated is a four wheel drive (4WD) loader  1  having: a cab  10 ; a rear body portion  20  with rear wheels  22 ; a front body portion  30  with front wheels  32 , a bucket  33 , a linkage  34  for working the bucket  33 , and hydraulic cylinders  34   a  and  34   b  to power the linkage  34 , and an articulation joint  35  allowing angular change between the front body portion  30  and the rear body portion  20 . Hydraulic cylinders  35   a ,  35   b  enable angular changes between the front and rear body portions  30 ,  20  under hydraulic power derived from conventional hydraulic pumps (not shown). 
       FIG. 2  illustrates an exemplary schematic of a first embodiment of removable or optional supplemental energy system (SES)  100  after integration with an exemplary conventional work vehicle energy system. The conventional energy system illustrated may include: an engine  40 ; an engine controller  50 ; a starter  60 ; conventions vehicle loads  70 ; and a vehicle controller  80  for power management. The exemplary supplemental energy system  100  may include: a bidirectional electric machine  110  having a motor-generator  110   a  and a bidirectional AC-DC converter  110   b  where AC is alternating current and DC is direct current; a rechargeable electrical storage system (RESS)  120 ; a converter controller  130 ; and the vehicle controller  80 . The particular RESS  120  illustrated is a capacitor but may be a battery or any other workable storage system designed to store electrical energy. 
     As illustrated, the vehicle controller  80  may be operatively connected to the engine controller  50  and the converter controller  130  for power management via control of the engine  40  and the supplemental energy system  100 . As illustrated, the connections between the vehicle controller  80  and the engine and converter controllers  50 ,  130  may be accomplished via a conventional means such as for example, a CAN bus  81 . Conventional vehicle loads may include, among other things, an alternator  71 , a hydraulic pump  72 , a water pump  73 , and a transmission  74  for powering the front and rear wheels  32 ,  22 . 
     As illustrated in  FIG. 2 , the motor-generator  110   a  may directly engage the flywheel  45  via the flywheel teeth  45   a  and the motor-generator engagement teeth  110   c ′ of a motor-generator engagement gear  110   c  in the same manner as the starter  60  and the starter engagement teeth  61   a  of a starter engagement gear  61 . As with the conventional starter  60 , the motor-generator  110   a  may be attached to the bell housing  90 , via a standard mounting flange  91  which may form a part of the bell housing  90  (as illustrated in  FIG. 3 ). Such an arrangement may require a plurality of mounting flanges  91 . However, the starter  60  and motor-generator  110   a  may indirectly engage the flywheel  45  via a gearbox  140  directly attached to a mounting flange  91  as illustrated in  FIG. 4 . 
     In operation, the starter  60  may be disengaged from the flywheel  45 , via a conventional clutching arrangement (not shown) after engine startup. The bidirectional electric machine  110  may be continually engaged with the flywheel  45  and be directed to deliver electrical power received from the RESS  120  to the flywheel  45  in the form of torque; to receive power from the flywheel  45  in the form of torque and deliver it to the RESS  120  in the form of electrical power, or to float and run in neutral, neither generating nor delivering power to the flywheel  45 . The bidirectional electric machine  110  directs power to the flywheel  45  by receiving electrical energy in the form of direct current (DC) from the RESS  120  via conventional electrical lines, converting DC to alternating current (AC) at the AC-DC converter  110   b  and supplying the AC to the motor-generator  110   a  which has been directed to act as a motor. The bidirectional electric machine  110  directs power to the RESS  120  by receiving energy from the flywheel  45  in the form of torque, converting the torque to AC via the motor-generator  110   a  which has been directed to act as a generator, converting the AC to DC via the AC-DC converter  110   b  and supplying the DC to the RESS  120  via conventional electrical lines. 
     As indicated in  FIG. 2 , the vehicle controller  80  may direct the engine  40  and the bidirectional machine  110  to power the vehicle  1 , via signals to the engine controller  50  and the converter controller  130 , in accordance with a control scheme effected via installed software. The control scheme may take many forms. For example, the vehicle controller  80  may direct the supplemental energy system  100  to deliver power to the flywheel  45  upon sensing a demand for an increase in mechanical power to accelerate the vehicle  1  when a signal from a conventional speed sensor indicates the speed of the vehicle  1  is below a predetermined speed in the desired direction of travel. The vehicle controller  80  may also direct the supplemental energy system  100  to deliver power to the flywheel  45  when it receives a signal from a control device such as, for example, a joystick, indicating that a demand is being made on the hydraulic pump (not shown) for operation of the hydraulic cylinders  34   a ,  34   b  which power the exemplary linkage  34  and bucket  33 . The vehicle controller  80  may direct the supplemental energy system  100  to deliver power from the flywheel  45  to the RESS  120  during periods when the vehicle  1  is running at low demand. The vehicle controller  80  manages the direction of energy flow between the flywheel  45  and the RESS  120  by directing the AC-DC converter  110   b  via signals to the converter controller  130  which directly controls the AC-DC converter  110   b.    
     As illustrated in the schematic of  FIG. 4 , in a second embodiment, the starter  60  and the bidirectional machine  110  may be mechanically connected to the flywheel  45  via a conventional gearbox  240  engaging the flywheel  45  via the gearbox engagement teeth  241   a  of a gearbox engagement gear  241  and a gearbox transfer gear  242  in direct contact with the motor-generator engagement teeth  110   c ′ and the starter engagement teeth  61   a  via transfer gear engagement teeth  242   a  and, as such, may utilize the same starter mounting flange  91  for torque transference. This arrangement may require the gearbox  240  to be directly attached to a starter mounting flange  91 . In this second embodiment, the operation of the supplemental energy system  100  may remain the same as with the first embodiment of the invention. As with the first exemplary embodiment, the starter  60  may be disengaged after engine startup. The simple gearbox  240  illustrated is exemplary; it may take many forms and may, for example have reduction gearing and multiple transfer gears but must have at least two areas for output, i.e., at least an output area for the starter  60  and an output area for the bidirectional machine  110 . 
     Having described the embodiments above, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.