Abstract:
A complementary regenerative torque system exists for a vehicle including an engine having an accelerator pedal position sensor; a transmission unit; and a drive shaft for driving a pair of wheels for propelling the vehicle. The regenerative torque system selectively stores and supplies energy to the drive train to provide on demand complementary torque thereto. The regenerative torque system may be either hydraulic or electric in nature and may be disposed upstream or downstream of the transmission relative to the engine. A regenerative torque control module is disposed between the accelerator pedal position sensor and the engine control module and intercepts the accelerator pedal position signal and modifies it in response to the mode of operation of the regenerative torque system and forwards the modified throttle signal to the engine control module. Likewise, the regenerative torque control module intercepts signals from the engine control module and modifies the same prior to broadcasting them to the rest of the vehicle&#39;s control modules.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention is directed to a controller for a complementary Regenerative Torque System (RTS) for a vehicle, the interface to the existing vehicle components, and the associated control thereof. 
   2. Description of the Related Art 
   Conventional vehicles have an internal combustion engine as a single source of torque.  FIG. 1  depicts a schematic flow chart of the signal and torque flow and associated control of a conventional four wheel drive vehicle. An Accelerator Pedal Position (APP) sensor is often employed to indicate desired engine torque while an Engine Control Module (ECM) controls the engine in response to the APP and other sensed conditions. The ECM communicates with a Transmission Control Module (TCM) which controls the transmission in accordance with APP, engine output torque, engine speed and vehicle speed, amongst other conditions. Such assemblies are well known in the art. These prior art systems do not have the ability to provide complementary or supplemental torque, or the ability to store or otherwise use the tremendous amount of energy wasted during vehicle deceleration. 
   The prior art has presented a wide variety of vehicular systems designed to capture and store a portion of the kinetic energy lost to brake heating in a decelerating vehicle, and to use the stored energy to re-accelerate the vehicle. Such systems often convert the torque of a drive shaft somewhere between the transmission and the axle of the vehicle drive wheels. Some systems employ electric hybrid components consisting of electric motor generators, batteries, and capacitors to convert kinetic energy while braking to electrical potential energy for driving the motor when torque is needed. Other systems employ hydraulic hybrid components consisting of pumps, motors and accumulators to convert kinetic energy while braking to hydraulic potential energy for driving the motor when torque is needed. 
   An example of a hydraulic RTS employs an integrated Pump Motor (P/M) which is driven by the drive train of the vehicle. The P/M shifts between a generative pump mode to charge a hydraulic accumulator and a motor mode which supplies torque to the drive train. Such pump motors are well known to those of ordinary skill on the art. Many such designs include a variable displacement P/M with a swash plate. When the swash plate is at zero angle, the pistons of the P/M are not reciprocating with respect to the cylinder block and the P/M is neither pumping nor motoring. The position of the swash plate is controlled in response to the mode of operation of the RTS. When braking, the P/M becomes a pump which charges a pressure accumulator. When accelerating, the pressure accumulator powers the P/M which then acts as a motor supplying torque the drive train. 
   All such prior devices and systems are costly and difficult to be installed with control systems of existing vehicles and are not especially adapted for simple integration with an existing control system and fail to provide the benefits associated with the assembly according to the present invention. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to a controller for a complementary RTS for a vehicle including an engine with associated controller; an APP sensor; a transmission unit with associated controller; a drive shaft for driving a pair of wheels for propelling the vehicle; and a regenerative torque unit. The regenerative torque unit selectively stores and supplies energy to the drive train to provide on-demand complementary torque thereto. The regenerative torque unit may be disposed upstream or downstream of the transmission relative to the engine. The Regenerative Torque Control Module (RTCM) is disposed between the existing vehicle wiring harness and the ECM, or other control modules as required, and intercepts pertinent signals entering and leaving the control modules and modifies the same signals in response to the mode of operation of the RTS. The invention allows the addition of a RTS to a vehicle without modification to the existing engine controller, transmission controller, or other system controllers. The invention also provides fail safe modes of operation in which the control signals revert to their original values in the event of a RTS failure. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic flow chart of the signal and torque flow and associated control thereof in a conventional four wheel drive vehicle. 
       FIG. 2  is a flow chart depicting the signal and torque flow and associated control thereof in a four wheel drive vehicle according to the present invention. 
       FIG. 3   a  is a schematic depiction of the RTS according to the present invention in a two-wheel drive vehicle, with the RTS between the engine and the transmission. 
       FIG. 3   b  is a schematic depiction of the RTS according to the present invention in a two-wheel drive vehicle, with the RTS between the transmission and the driveshaft. 
       FIG. 4  is a conventional internal combustion engine with a wire harness bundle connected to an engine&#39;s ECM. 
       FIG. 5  is a wire harness schematic of the internal combustion engine of  FIG. 4 . 
       FIG. 6  is a wire harness schematic according to the present invention implemented with a single module interface. 
       FIG. 7  is a wire harness schematic according to the present invention implemented with a multiple module interface. 
       FIG. 8  is a schematic showing the typical pass-through failsafe wiring arrangement according to the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 2-3  depict an assembly according to preferred embodiments of the invention. An internal combustion engine  1  serves as a primary source of torque for driving a drive train which includes a transmission  3 , associated drive shafts, differentials between driven wheels, and in the case of four wheel drive vehicles, a transfer case  5  to provide torque split between front and rear axles. A regenerative torque source ( 12 ) is employed for supplying auxiliary torque on demand to the drive train and for storing energy during deceleration/vehicle braking. A torque summation device (Such as integrated pump/motor)( 10 ) is disposed between the engine and transmission in one preferred embodiment. 
   The present invention is particularly suited for delivering complementary torque to the drive train as needed. The amount of torque delivered to the transmission is the sum of the torque supplied by the engine and the torque supplied by the regenerative torque source. Depending on vehicle conditions, such as torque demand, and the amount of torque available from either the engine or the regenerative torque source  10 / 12 , the Regenerative Torque Control Module ( 20 ) RTCM serves to control the amount of torque delivered by the engine and regenerative torque source. The RTCM  20  computes how to split the delivery of torque between the engine  1  and regenerative torque source  10 / 12 . Torque supplied by the regenerative torque source may be either supplementary (additive) or complementary (replacement) to the engine torque. The percentage of torque supplied by the engine or regenerative torque source depends on the operating conditions of the vehicle, torque demand, and the available torque that can be supplied by either source at a given time. The resultant torque is the sum of the two torque sources. The RTCM  20  contains the necessary algorithms to control the regenerative torque source for selectively and appropriately supplying torque to the drive train as needed. The engine, on the other hand, is controlled by an (electronic control module) ECM  22 , usually supplied by the manufacturer of the engine. 
   Modern internal combustion engines are very complex. The engines are controlled in response to an array of sensed vehicle conditions. Sensors such as oxygen sensors, vehicle speed sensors, engine speed sensors, and a host of other inputs are all used by the ECM  22  to efficiently manage the engine&#39;s performance. Firing sequencing, control of injectors etc. are all dynamic parts of a modern working engine. One of the sensed parameters is the Accelerator Pedal position sensor  24  (APP). Sensing the position of the accelerator pedal provides the primary request for torque from the engine. However, when a regenerative torque source applies complementary torque to the drive line the engine will not be controlled accurately. This is because, for a given torque demand indicated by the APP sensor  24 , the engine  1  will attempt to supply the torque as requested by the APP  24  sensor without knowledge that a portion of the desired torque is being supplied by the regenerative torque source  10 / 12 . This may result in an inconsistent torque response from the accelerator pedal. This is undesirable as it makes driving unintuitive, creates a distraction for the driver, and requires a particular skill to handle the operation of the vehicle during regenerative torque delivery. To overcome these problems, the RTCM intercepts and modifies the APP signal. 
   As previously described, the APP is normally sent directly to the ECM  22 . However, in the arrangement of the present invention, the APP is intercepted by the RTCM  20 . The RTCM  20  then modifies this signal appropriately when supplying auxiliary torque via the regenerative torque source  10 / 12 . For example, when the driver depresses the accelerator pedal, the vehicle conditions may warrant supplying a large amount of torque via the regenerative torque source  10 / 12 . In such an instance, little torque may be required from the engine  1 . If the engine  1  were to receive the original APP signal  24 , it would deliver too much torque and the vehicle would not operate in accordance with the driver&#39;s expectations. To prevent such a scenario, the RTCM  20  modifies the APP  24  signal to artificially indicate a lesser accelerator pedal depression. This results in an ultimate torque delivery to the transmission  3  in accordance with the driver&#39;s desire. As the RTCM  20  requests less torque from the regenerative torque source  10 / 12 , the RTCM  2  modifies the APP  24  as seen by the ECM  22  to cause the engine  1  to increase its percentage of torque as needed. When conditions no longer require the application of any auxiliary torque, the actual APP  24  is sent unmodified to the ECM  22 . 
   In modern conventional vehicles, the ECM  22  also communicates with other system control modules, in particular the Transmission Control Module TCM  30 , through a communication bus or other means. The TCM  30  may use the APP  24 , engine torque signal or other signals generated by the ECM  22  to implement shift strategy. When complementary torque is being supplied by the regenerative torque source  10 / 12 , the transmission  3  would receive misleading signals from the ECM  22  and shift inappropriately. This is a result of the TCM  30  receiving signals representative of only the torque from the engine  1  when in fact is getting the sum of both engine torque and the torque supplied by the regenerative torque source  10 / 12 . To correct this drawback, the RTCM  20  intercepts the torque signal generated by the ECM  22  and modifies it accordingly as it supplies auxiliary torque from the regenerative torque source. The modified torque signal consists of a scaled sum of the percentage of engine torque and auxiliary torque. In this manner other control modules connected to the vehicle&#39;s communication bus are unaware of the torque split. For transmissions that utilize the APP  24  sensor, this signal may be modified by the RTCM  20  as well. 
     FIG. 4  depicts a perspective view of a conventional engine with an ECM.  FIG. 5  shows an engine wiring harness connected to the ECM while a vehicle wiring harness connects the ECM to all the various systems throughout the vehicle. Because of the sophistication of modern engines and associated control modules, it not practical to replace the ECM or any other existing control module for every vehicle incorporating a RTS. Such would require a different RTCM  20  for each type of engine/transmission combination. Thus it is desirable to maintain the use of the original ECM  22  and employ a retrofit arrangement whereby the RTCM  20  employs a pass-through device to allow an easy and simple retrofit connection without jeopardizing the original ECM&#39;s  22  ability to receive all the various sensed conditions and signals and continue to control all of the various system components. The RTCM  20  controls the RTS and intercepts and modifies only those signals which would otherwise incorrectly influence other control modules or systems.  FIG. 6  depicts an implementation according to a preferred embodiment of the present invention. The RTCM  20  is connected to the vehicle wire harness bundle connector ordinarily connected to the ECM  22 . The connection mirrors that of the ECM  22 . For systems involving multiple signals to different modules ( FIG. 7 ), each wiring harness is duplicated in similar manner. For implementation across multiple engine/ECM  22  platforms, the RTCM  20  may employ an adapter between the RTCM  20  and the wire harness. The RTCM  20  intercepts the APP  24  and any other signal that it needs to modify prior to broadcast to other system controllers. A second wire harness is provided from the RTCM  20  to the ECM  22 . For a plurality of bundled wires within the wire harness carrying various signals, they are simply passed through the RTCM  20  unaltered and forwarded to the ECM  22 . 
   The output of the ECM  22  is also channeled back through the RTCM  20 . Most of the ECM  22  output signals are simply passed through to the remaining vehicle systems/components. However, the RTCM  20  intercepts the signals such as the engine torque signal. During delivery of complementary torque, the engine  1  is providing only a fraction of the total driveline torque. The RTCM  20  modifies the engine torque signal to reflect the total torque applied to the transmission  3 . This signal is sent to the TCM  30  and any other control modules in the vehicle. 
   During vehicle deceleration, the RTS acts as a storage device. It is known in the art that energy conversion devices, such as pump motors and motor generators, are most efficient at specific speeds and thus are tuned accordingly. Therefore, during deceleration, it is desirable to control the transmission  3  in an effort to rotate the drive shaft within a specified speed range thereby maximizing the efficiency of the energy conversion device and increasing stored energy. The RTCM  20  has full access to all the vehicle sensed parameters. The engine torque, APP  24  and other signals may be modified by the RTCM  20  before being sent to the TCM  30 , thus forcing the TCM  30  to maintain shift points beneficial to energy conversion device operation and energy storage. This is valid for the configuration where energy is extracted between the engine  1  and transmission  3 . For a RTS extracting torque below the transmission, a similar modification may benefit the energy recovery by maintaining a condition where engine braking is minimized. This mode of operation is a divergence from conventional down-shifting which is largely dependent on having the transmission shifted to make use of engine braking torque. The environment of a hybrid RTS is very much different from conventional drive trains. The invention allows modification of vehicle transmission  3  operation during deceleration, to optimize energy conversion device speed which is heretofore void in the art. 
   The RTCM  20  is configured such that in the event that the RTS is disabled or inoperative, the signals that are intercepted by the RTCM  20  are switched automatically so as to pass through the unmodified control signals.  FIG. 8  shows the typical mechanism for this failsafe circuit. Each signal entering and exiting the RTCM  20  is switched by a relay or other switching device. The switch defaults to bypass mode. When the RTCM  20  is powered and operating without fault conditions, the relay is switched on, which directs the control signal through the RTCM  20 . This arrangement allows the original ECM  22 , TCM  30  or other control modules to operate normally in the event of a failure or shutdown of the RTS. 
   For example, in the event of a power loss to the RTS, the RTS will be unable to store energy, and will be disabled. In this case, the failsafe relay circuitry will de-energize, and the engine, transmission, and other vehicle systems will continue to operate normally. The fail safe relay circuit can also respond to bypass input signals in response to other fault detected operating conditions. 
   While the foregoing invention has been shown and described with reference to a preferred embodiment, it will be understood by those possessing skill in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.