SYSTEM AND METHOD FOR MANAGING A POWERTRAIN IN A VEHICLE

• US 20070193808A1
• Filed: 02/21/2006
• Published: 08/23/2007
• Est. Priority Date: 02/21/2006
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Rodrigues, Ashok, Perakes, Andreas
• Granted Patent: US 7,870,925 B2
• Time in Patent Office: Days
• US Class Current: 180/242
• CPC Class Codes: B60K 17/356 having fluid or electric motor, for driving one or more wheels disposition of motor in, or adjacent to, traction wheel B60K7/00
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/10 Controlling the power contribution of each of the prime movers to meet required power demand
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2552/40 Coefficient of friction
• CPC Class Codes: Y02T 10/62 Hybrid vehicles

Abstract

A system and method for managing a powertrain in a vehicle determines a number of vehicle conditions, and compares them to predetermined conditions to determine whether a secondary axle of the vehicle should be automatically connected to or disconnected from the powertrain. In general, if the speed of the vehicle is above some predetermined speed threshold, the secondary axle is disengaged to increase fuel economy. Conversely, if the speed of the vehicle is below some predetermined threshold, the secondary axle is typically engaged to help maximize the capture of regenerative braking energy during a braking event. Additional vehicle conditions may be examined, and exceptions to the general rule utilized, to further enhance the control strategy.

Claims

1. A method for managing a powertrain in a vehicle including a front drive wheel and a rear drive wheel, the vehicle being operable in at least a first driving mode in which the front and rear drive wheels are selected to drive the vehicle, at least one of the drive wheels having a changeable connection status to the powertrain such that it is selectively connectable to and disconnectable from the powertrain, the method comprising:

determining at least one vehicle condition, including at least one of a speed of the vehicle and whether the vehicle is operating in the first driving mode;

comparing at least one of the determined vehicle conditions to a respective predetermined condition; and

changing the connection status of at least one of the drive wheels based on the comparison of the at least one determined vehicle condition to its respective predetermined condition.

2. The method of claim 1, wherein the step of changing the connection status of the at least one drive wheel includes disconnecting the at least one drive wheel from the powertrain when the speed of the vehicle is above a predetermined speed threshold, the vehicle is not operating in the first driving mode, and the at least one drive wheel is connected to the powertrain.

3. The method of claim 1, wherein the step of changing the connection status of the at least one drive wheel includes connecting the at least one drive wheel to the powertrain when the speed of the vehicle is above a predetermined speed threshold, the vehicle is operating in the first driving mode, the vehicle is operating on a surface having a coefficient of friction less than a predetermined coefficient of friction, and the at least one drive wheel is not connected to the powertrain.

4. The method of claim 1, wherein the step of changing the connection status of the at least one drive wheel includes connecting the at least one drive wheel to the powertrain when the speed of the vehicle is not above a predetermined speed threshold, the vehicle is operating in the first driving mode, and the at least one drive wheel is not connected to the powertrain.

5. The method of claim 1, the powertrain including an electric motor arrangement operable to supply torque to at least one of the drive wheels, the vehicle including a power supply for storing electrical energy and for providing electrical energy to the motor arrangement, and wherein the step of changing the connection status of the at least one drive wheel includes connecting the at least one drive wheel to the powertrain when the speed of the vehicle is not above a predetermined speed threshold, the vehicle is not operating in the first driving mode, a state of charge of the power supply is not above a predetermined state of charge threshold, and the at least one drive wheel is not connected to the powertrain.

6. The method of claim 1, the powertrain including an electric motor arrangement operable to supply torque to at least one of the drive wheels, the vehicle including a power supply for storing electrical energy and for providing electrical energy to the motor arrangement, and wherein the step of determining at least one vehicle condition includes determining if the vehicle is being operated in a city driving mode characterized by at least one of a predetermined number of speed changes of the vehicle over time, changes in a state of charge of the power supply over time, a function of power supply output over time, or vehicle position information, and

wherein changing the connection status of the at least one drive wheel includes connecting the at least one drive wheel to the powertrain when the speed of the vehicle is not above a predetermined speed threshold, the vehicle is not operating in the first driving mode, a state of charge of the power supply is above a predetermined state of charge threshold, the vehicle is being operated in the city driving mode, and the at least one drive wheel is not connected to the powertrain.

7. The method of claim 1, the powertrain including an electric motor arrangement operable to supply torque to at least one of the drive wheels, the vehicle including a power supply for storing electrical energy and for providing electrical energy to the motor arrangement, and wherein the step of determining at least one vehicle condition includes determining if the vehicle is being operated in a city driving mode characterized by at least one of a predetermined number of speed changes of the vehicle over time, changes in a state of charge of the power supply over time, a function of power supply output over time, or vehicle position information, and

wherein changing the connection status of the at least one drive wheel includes disconnecting the at least one drive wheel from the powertrain when the speed of the vehicle is not above a predetermined speed threshold, the vehicle is not operating in the first driving mode, a state of charge of the power supply is above a predetermined state of charge threshold, the vehicle is not being operated in the city driving mode, and the at least one drive wheel is connected to the powertrain.

8. A method for managing a powertrain in a vehicle, the powertrain including an electric motor arrangement operable to provide torque to at least a first pair of drive wheels proximate one end of the vehicle, the vehicle including a second pair of drive wheels proximate another end of the vehicle, the second pair of drive wheels having a changeable connection status to the powertrain such that it is selectively connectable to and disconnectable from the powertrain, the vehicle further including a selection device for selectively placing the vehicle in a four-wheel-drive mode or a two-wheel-drive mode, the method comprising:

determining a speed of the vehicle;

determining whether the vehicle is in the two-wheel-drive mode or the four-wheel drive mode; and

disconnecting the second pair of drive wheels from the powertrain when it is determined that the speed of the vehicle is above a predetermined speed threshold, the vehicle is in the two-wheel-drive mode, and the second pair of drive wheels is connected to the powertrain.

9. The method of claim 8, further comprising:

determining a coefficient of friction between the vehicle and a road surface;

disconnecting the second pair of drive wheels from the powertrain when the speed of the vehicle is above the first predetermined speed threshold, the vehicle is in the four-wheel-drive mode, the coefficient of friction is not less than a predetermined coefficient of friction, and the second pair of drive wheels is connected to the powertrain; and

connecting the second pair of drive wheels to the powertrain when the speed of the vehicle is above the first predetermined speed threshold, the vehicle is in the four-wheel-drive mode, the coefficient of friction is less than a predetermined coefficient of friction, and the second pair of drive wheels is not connected to the powertrain.

10. The method of claim 8, further comprising connecting the second pair of drive wheels to the powertrain when the speed of the vehicle is not above the predetermined speed threshold, the vehicle is in the four-wheel-drive mode, and the second pair of drive wheels is not connected to the powertrain.

11. The method of claim 10, the vehicle further including a power supply for storing electrical energy and for providing electrical energy to the motor arrangement, the method further comprising connecting the second pair of drive wheels to the powertrain when the speed of the vehicle is not above the predetermined speed threshold, the vehicle is in the two-wheel-drive mode, a state of charge of the power supply is not above a predetermined state of charge threshold, and the second pair of drive wheels is not connected to the powertrain.

12. The method of claim 11, further comprising:

determining whether the vehicle is being operated in a city driving mode, the city driving mode being characterized by at least one of a predetermined number of speed changes of the vehicle over time, changes in a state of charge of the power supply over time, a function of power supply output over time, or vehicle position information; and

connecting the second pair of drive wheels to the powertrain when the speed of the vehicle is not above the predetermined speed threshold, the vehicle is in the two-wheel-drive mode, a state of charge of the power supply is above a predetermined state of charge threshold, the vehicle is being operated in the city driving mode, and the second pair of drive wheels is not connected to the powertrain.

13. The method of claim 12, further comprising disconnecting the second pair of drive wheels from the powertrain when the speed of the vehicle is not above the predetermined speed threshold, the vehicle is in the two-wheel-drive mode, a state of charge of the power supply is above a predetermined state of charge threshold, the vehicle is not being operated in the city driving mode, and the second pair of drive wheels is connected to the powertrain.

14. A system for managing a powertrain in a vehicle, the powertrain including an electric motor arrangement operable to provide torque to at least a first drive wheel proximate one end of the vehicle, the vehicle including a second drive wheel proximate another end of the vehicle, and a power supply for storing electrical energy and for providing electrical energy to the motor arrangement, the vehicle being operable in at least a first driving mode in which the first and second drive wheels are selected to drive the vehicle, the system comprising:

a disconnect disposed between the second drive wheel and the powertrain and operable to selectively connect the second drive wheel to, and disconnect the second drive wheel from, the powertrain; and

a control system including at least one controller, the control system being in communication with the disconnect, the control system being configured to determine a speed of the vehicle and whether the vehicle is operating in the first driving mode, and further configured to effect operation of the disconnect to disconnect the second drive wheel from the powertrain when the speed of the vehicle is above a predetermined speed threshold, the vehicle is not operating in the first driving mode, and the second drive wheel is connected to the powertrain.

15. The system of claim 14, wherein the control system is further configured to receive signals related to a coefficient of friction between the vehicle and a road surface, and to effect operation of the disconnect to disconnect the second drive wheel from the powertrain when the speed of the vehicle is above a predetermined speed threshold, the vehicle is operating in the first driving mode, the coefficient of friction is not less than a predetermined coefficient of friction, and the second drive wheel is connected to the powertrain.

16. The system of claim 15, wherein the control system is further configured to effect operation of the disconnect to connect the second drive wheel to the powertrain when the speed of the vehicle is above a predetermined speed threshold, the vehicle is operating in the first driving mode, the coefficient of friction is less than a predetermined coefficient of friction, and the second drive wheel is not connected to the powertrain.

17. The method of claim 14, wherein the control system is further configured to effect operation of the disconnect to connect the second drive wheel to the powertrain when the speed of the vehicle is not above a predetermined speed threshold, the vehicle is operating in the first driving mode, and the second drive wheel is not connected to the powertrain.

18. The method of claim 17, wherein the control system is further configured to effect operation of the disconnect to connect the second drive wheel to the powertrain when the speed of the vehicle is not above a predetermined speed threshold, the vehicle is not operating in the first driving mode, a state of charge of the power supply is not above a predetermined state of charge threshold, and the second drive wheel is not connected to the powertrain.

19. The method of claim 18, wherein the control system is further configured to receive signals related to whether the vehicle is operating in a city driving mode, the city driving mode being characterized by at least one of speed changes of the vehicle over time, changes in a state of charge of the power supply over time, a function of power supply output over time, or vehicle position information, the control system being further configured to effect operation of the disconnect to connect the second drive wheel to the powertrain when the speed of the vehicle is not above a predetermined speed threshold, the vehicle is not operating in the first driving mode, a state of charge of the power supply is above a predetermined state of charge threshold, the vehicle is being operated in the city driving mode, and the second drive wheel is not connected to the powertrain.

20. The method of claim 19, wherein the control system is further configured to effect operation of the disconnect to disconnect the second drive wheel from the powertrain when the speed of the vehicle is not above a predetermined speed threshold, the vehicle is not operating in the first driving mode, a state of charge of the power supply is above a predetermined state of charge threshold, the vehicle is not being operated in the city driving mode, and the second drive wheel is connected to the powertrain.