Abstract:
A regenerative braking control system includes at least one sensor adapted to sense a front tire impact event and transmit a sensor signal responsive to the front tire impact event during vehicle braking and a regenerative powertrain interfacing with the at least one sensor and adapted to reduce regenerative braking torque responsive to receiving the sensor signal from the at least one sensor. A regenerative braking control method is also disclosed.

Description:
FIELD 
       [0001]    Illustrative embodiments of the disclosure generally relate to regenerative braking. More particularly, illustrative embodiments of the disclosure relate to a regenerative braking control system and method which facilitate enhanced control of regenerative braking without compromising vehicle stability during front tire impact events. 
       BACKGROUND 
       [0002]    To improve fuel economy, hybrid electric vehicles (HEVs) may utilize regenerative (regen) braking, in which kinetic energy is converted by an electric machine into storable energy during braking and then made available for vehicle propulsion. During front tire impact events as occur when one or both front tires of the vehicle encounter a bump, pothole, patch of ice or the like, regenerative braking may not be modified accordingly, potentially compromising regenerative braking efficiency. 
         [0003]    Accordingly, a regenerative braking control system and method which facilitates enhanced control of regenerative braking without compromising vehicle stability during front tire impact events is needed. 
       SUMMARY 
       [0004]    Embodiments of the disclosure are generally directed to a regenerative braking control system. An illustrative embodiment of the regenerative braking control system includes at least one sensor adapted to sense a front tire impact event and transmit a sensor signal responsive to the front tire impact event during vehicle braking and a regenerative powertrain interfacing with the at least one sensor and adapted to reduce regenerative braking torque responsive to receiving the sensor signal from the at least one sensor. 
         [0005]    Embodiments of the disclosure are further generally directed to a regenerative braking control method. An illustrative embodiment of the regenerative braking control method includes determining whether a front tire impact event is occurring during vehicle braking and reducing application of regeneration torque if the front tire impact event is occurring. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    Illustrative embodiments of the disclosure will now be described, by way of example, with reference to the accompanying drawings, in which: 
           [0007]      FIG. 1  is a schematic block diagram of an illustrative embodiment of the regenerative braking control system; and 
           [0008]      FIG. 2  is a block diagram of an alternative illustrative embodiment of a regenerative braking control method. 
       
    
    
     DETAILED DESCRIPTION 
       [0009]    The following detailed description is merely exemplary in nature and is not intended to limit the described embodiments or the application and uses of the described embodiments. As used herein, the word “exemplary” or “illustrative” means “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” or “illustrative” is not necessarily to be construed as preferred or advantageous over other implementations. All of the implementations described below are exemplary implementations provided to enable persons skilled in the art to practice the disclosure and are not intended to limit the scope of the claims. Moreover, the illustrative embodiments described herein are not exhaustive and embodiments or implementations other than those which are described herein and which fall within the scope of the appended claims are possible. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. 
         [0010]    Referring initially to  FIG. 1 , an illustrative embodiment of the regenerative braking control system, hereinafter system, is generally indicated by reference numeral  100 . The system  100  may include a vehicle  102 . In some embodiments, the vehicle  102  may include a hybrid electric vehicle (HEV) or a plug-in hybrid electric vehicle (PHEV), for example and without limitation. The vehicle  102  may have a front axle  104  with a pair of front wheels  105  and a rear axle  106  with a pair of rear wheels  107 . In some embodiments, the vehicle  102  may be driven by the rear wheels  107 . 
         [0011]    A regenerative powertrain  108  may interface with at least one of the front axle  104  and the rear axle  106  of the vehicle  102 . In some embodiments, the regenerative powertrain  108  may interface with one or more front wheels  105  and/or one or more rear wheels  107  of the vehicle  102 . The regenerative powertrain  108  may be adapted to apply regenerative braking torque to the front axle  104  and/or the rear axle  106  during braking of the vehicle  102 , typically in the conventional manner. The regenerative powertrain  108  may be adapted to convert mechanical power from the rotating front axle  104  and/or rear axle  106  into electrical power. The electrical power may be stored in a battery or other suitable electrical storage facility  110  which electrically interfaces with the regenerative powertrain  108 . The electrical power which is stored in the electrical storage facility  110  may be used in propulsion of the vehicle  102  such as in the conventional manner. 
         [0012]    At least one wheel slip sensor  112  may interface with the regenerative powertrain  108 . The wheel slip sensor  112  may interface with the front wheels  105  and/or the rear wheels  107  of the vehicle  102  as is known by those skilled in the art. During operation of the vehicle  102 , the wheel slip sensor  112  may be adapted to detect wheel slip events of the front wheels  105  and/or the rear wheels  107  of the vehicle  102  using a limited slip control detection algorithm such as in the conventional manner. The wheel slip sensor  112  may be further adapted to transmit a wheel slip sensor signal  114  which indicates the wheel slip events to the regenerative powertrain  108 . In some embodiments, the wheel slip sensor  112  may be adapted to detect wheel slip events at the front wheels  105  and responsively transmit the wheel slip sensor signal  114  to the regenerative powertrain  108  in the event that the front wheels  105  encounter a front tire impact event such as a bump, pothole, ice patch or the like. 
         [0013]    In some embodiments, at least one vehicle motion sensor  120  may interface with the regenerative powertrain  108 . The vehicle motion sensor  120  may include at least one wheel speed sensor and/or at least one acceleration sensor (such as a longitudinal acceleration sensor, a lateral acceleration sensor, etc.) or deceleration sensor, for example and without limitation. The vehicle motion sensor  120  may be adapted to transmit a motion sensor signal  122  which indicates the wheel speed of at least one of the front wheels  105  and the rear wheels  107  and/or acceleration or deceleration of the vehicle  102  to the regenerative powertrain  108 . In some embodiments, the vehicle motion sensor  120  may be adapted to detect wheel speed and/or vehicle acceleration or deceleration and responsively transmit the motion sensor signal  122  to the regenerative powertrain  108  in the event that the front wheels  105  encounter the front tire impact event such as a bump, pothole, ice patch or the like. 
         [0014]    The regenerative powertrain  108  may be adapted to reduce the regenerative braking torque which is applied to the front wheels  105  and/or the rear wheels  107  in the event that the regenerative powertrain  108  receives the wheel slip sensor signal  114  and/or the motion sensor signal  122  responsive to the front tire impact event. The magnitude of regenerative braking torque reduction may be proportional to the magnitude of wheel slip which is detected at the front wheels  105  during the front tire impact event. 
         [0015]    In exemplary application of the system  100 , the regenerative powertrain  108  applies regenerative braking torque to the front axle  104  and/or the rear axle  106  during braking of the vehicle  102 . The regenerative powertrain  108  generates electrical power which may be stored in the electrical storage facility  110  and may be used in propulsion of the vehicle  102 . 
         [0016]    In the event that the front wheels  105  encounter a front tire impact event during vehicle braking, the wheel slip sensor  112  may detect wheel slippage at the front wheels  105  and responsively transmit the wheel slip sensor signal  114  to the regenerative powertrain  108 . Additionally or alternatively, the vehicle motion sensor  120  may detect acceleration, deceleration and/or other vehicle motion and responsively transmit the motion sensor signal  120  to the regenerative powertrain  108 . The regenerative powertrain  108  may use the wheel slip and/or vehicle motion data to reduce regenerative braking torque at the rear wheels  107 . The magnitude of the reduction in regenerative braking torque at the rear wheels  107  may be in proportion to the magnitude of wheel slippage which is detected by the wheel slip sensor  112  at the front wheels  105  and/or the magnitude of vehicle motion which is detected by the vehicle motion sensor  120 . Therefore, the regenerative powertrain  108  may utilize the motion sensor signal  122  from the vehicle motion sensor  120  and/or the drive shaft position sensor signal  114  from the drive shaft position sensor  112  to inhibit regenerative braking torque during braking of the vehicle  102  and maintain stability of the vehicle  102  during the front tire impact event. 
         [0017]    Referring next to  FIG. 2  of the drawings, a block diagram  200  of an illustrative embodiment of a regenerative braking control method is shown. The method  200  begins at block  202 . At block  204 , a determination may be made as to whether vehicle braking is being applied. If vehicle braking is not being applied, then the method may end at block  206 . If vehicle braking is being applied at block  204 , then at block  208  a determination may be made as to whether a front tire impact event is occurring. The front tire impact event may be detected based on wheel slip data and/or vehicle motion data. 
         [0018]    If a front tire impact event is not occurring at block  208 , then the method may end at block  206 . If a front tire impact event is occurring, then regenerative braking torque at the rear wheels may be reduced at block  210 . The magnitude of regenerative braking reduction may be proportional to the magnitude of slip which is detected at the front wheels and/or the magnitude of vehicle motion which is detected during the front tire impact event. 
         [0019]    Although the embodiments of this disclosure have been described with respect to certain exemplary embodiments, it is to be understood that the specific embodiments are for purposes of illustration and not limitation, as other variations will occur to those of skill in the art.