VEHICLE TORQUE MANAGEMENT

• US 20110106388A1
• Filed: 11/04/2009
• Published: 05/05/2011
• Est. Priority Date: 11/04/2009
• Status: Active Grant

• Current Assignee: Daimler Trucks North America LLC (Mercedes-Benz Group AG)
• Original Assignee: Daimler Trucks North America LLC (Mercedes-Benz Group AG)
• Inventors: Duraiswamy, Shivkumar, Boeckenhoff, Elmar, Reckels, Dieter, Rotz, Derek James
• Granted Patent: US 9,020,726 B2
• Time in Patent Office: Days
• US Class Current: 701/70
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 2552/15 Road slope, i.e. the inclination of a road segment in the longitudinal direction
• CPC Class Codes: B60W 2552/20 Road profile, i.e. the change in elevation or curvature of a plurality of continuous road segments
• CPC Class Codes: B60W 2556/10 Historical data
• CPC Class Codes: B60W 2710/0666 Engine torque
• CPC Class Codes: B60W 30/1882 characterised by the working point of the engine, e.g. by using engine output chart
• CPC Class Codes: B60W 40/072 Curvature of the road
• CPC Class Codes: B60W 40/076 Slope angle of the road
• CPC Class Codes: B60W 40/13 Load or weight
• CPC Class Codes: B60W 50/12 Limiting control by the driver depending on vehicle state, e.g. interlocking means for the control input for preventing unsafe operation

Abstract

A torque management system and method is described by which the torque provided by an engine can be controlled based on a mass of the vehicle and, if available, instantaneous and/or predictive slope information. Also, in some modes of operation, torque can be controlled based on speed limit information for upcoming road segments to be traveled by a vehicle. In addition to controlling the maximum allowable torque, optionally the minimum allowable torque can also be controlled to prevent inadvertent decelerations of the vehicle. A driver/operator can optionally override the torque control and the history of override requests can optionally be used to adjust overrides of the system. A plurality of torque control approach sub-methods can be made available with the appropriate sub-mode being selected depending, for example, upon the extent of the available information.

Claims

1. A computer implemented method of establishing the maximum allowable engine torque for a vehicle comprising:

determining the mass of the vehicle;

determining the slope of the upcoming road on which the vehicle is to travel;

calculating a maximum allowable engine torque for the engine of the vehicle using longitudinal dynamics equations for the vehicle and based at least in part upon the mass of the vehicle and the slope of the road on which the vehicle is to travel; and

selectively limiting the maximum torque of the vehicle engine to the calculated maximum allowable torque under engine operating conditions wherein the engine is not under the control of a vehicle cruise control system.

2. A method according to claim 1 wherein the act of determining the slope comprises determining the slope of the road where the vehicle is to travel utilizing a 3-dimensional map database.

3. A method according to claim 1 wherein the act of determining the slope comprises predictively determining the slope of the road for a plurality of upcoming road segments where the vehicle is to travel and in the expected direction of travel by the vehicle.

4. A method according to claim 3 comprising the act of repeatedly determining the slope of the road for upcoming road segments as the vehicle is traveling.

5. A method according to claim 3 comprising the act of determining the respective speed limits for a plurality of upcoming road segments where the vehicle is to travel and in the expected direction of travel by the vehicle and wherein the act of calculating a maximum allowable engine torque is based at least in part upon the respective speed limits for the upcoming road segments.

6. A method according to claim 5 comprising the act of repeatedly determining the slope of the road for upcoming road segments and repeatedly determining the speed limits for respective upcoming road segments as the vehicle is traveling and wherein the act of calculating a maximum allowable engine torque is based at least in part upon the determined slope and speed limits for the upcoming road segments.

7. A method according to claim 1 wherein the maximum allowable engine torque is calculated at least in part based upon a plurality of vehicle parameters.

8. A method according to claim 7 wherein the vehicle parameters comprise:

9. A method according to claim 7 wherein the vehicle parameters comprise:

10. A method according to claim 1 comprising the act of determining the engine speed and wherein the act of selectively limiting the maximum allowable engine torque is restricted to times when the engine speed is in a non-fuel efficient portion of an engine torque speed map for the engine and when the engine speed is greater than a low engine speed threshold.

11. A method according to claim 1 further comprising not limiting the maximum torque of the vehicle engine and allowing the maximum torque permitted by a maximum allowable torque curve for a vehicle with a gross vehicle weight rated load for an acceleration override time in response to a maximum acceleration request input.

12. A method according to claim 11 comprising changing the duration of the acceleration override time based upon the history of maximum acceleration request inputs.

13. A method according to claim 12 comprising the act of storing the number of maximum acceleration request inputs to create a history of maximum acceleration request inputs in an override evaluation time interval, the method also comprising the act of reducing the duration of the acceleration override time in the event the number of maximum acceleration request inputs in an override evaluation time interval have exceeded a threshold.

14. A method according to claim 11 comprising the act of limiting the torque to the calculated allowable maximum engine torque in the absence of one or more of the following exceptions:

a maximum acceleration request input, or the engine speed is below a low speed threshold.

15. A method according to claim 1 wherein the act of calculating the maximum allowable engine torque comprises:

calculating the torque required to maintain the vehicle at the current velocity of the vehicle;

calculating the torque available for acceleration of the vehicle;

calculating the maximum possible acceleration;

computing the percentage reduction in maximum acceleration based upon a prediction using the upcoming road grade;

calculating the maximum allowable acceleration (MAA);

based on the MAA, calculating the maximum allowable torque (MAT);

determining whether a vehicle operator has requested a torque that is greater than the MAT and if no, allow the vehicle operator requested torque and if yes, selectively limit the maximum allowable torque to the MAT.

16. A method according to claim 15 wherein if the operator requested torque is greater than the MAT, limiting the maximum allowable torque to the MAT in the absence of an acceleration override request.

17. A method according to claim 1 comprising the act of selectively limiting the minimum torque of the vehicle engine under engine operating conditions wherein the engine is not under the control of a vehicle cruise control system.

18. A method according to claim 17 comprising the act of calculating a minimum allowable engine torque of the engine of the vehicle based at least in part upon the mass of the vehicle and the slope of the road on which the vehicle is to travel, and comprising the act of selectively limiting the minimum torque of the vehicle engine to the minimum allowable engine torque under engine operating conditions wherein the engine is not under the control of a vehicle cruise control system.

19. A method of establishing the maximum allowable engine torque for a vehicle comprising selecting from and applying at least one torque limiting sub-methods from a plurality of available torque limiting sub-methods, the available torque limiting sub-methods comprising at least sub-methods A, B, and C below:

A. establishing the maximum allowable engine torque to be equal to the torque under a Max Torque Curve for the vehicle at the maximum gross vehicle weight rated load for the vehicle;

B. determining the instantaneous slope of the road on which the vehicle is to travel;

calculating a maximum allowable engine torque for the engine of the vehicle based at least in part upon the mass of the vehicle and the instantaneous slope of the road on which the vehicle is to travel;

selectively limiting the maximum torque of the vehicle engine to the calculated maximum allowable engine torque if the engine is not being controlled by a vehicle cruise control system;

C. predictively determining the slope of the road for a plurality of upcoming road segments where the vehicle is to travel and in the expected direction of travel by the vehicle;

calculating a maximum allowable engine torque for the engine of the vehicle based at least in part upon the mass of the vehicle and the slope of the upcoming road segments on which the vehicle is to travel;

selectively limiting the maximum torque of the vehicle engine to the calculated maximum allowable engine torque if the engine is not being controlled by a vehicle cruise control system; and

20. A method according to claim 19 wherein the available torque limiting sub-methods also comprise sub-method D below:

D. predictively determining the slope of the road for a plurality of upcoming road segments where the vehicle is to travel and in the expected direction of travel by the vehicle;

calculating a maximum allowable engine torque for the engine of the vehicle based at least in part upon the mass of the vehicle and the slope of the upcoming road segments on which the vehicle is to travel;

selectively limiting the maximum torque of the vehicle engine to the calculated maximum allowable engine torque if the engine is not being controlled by a vehicle cruise control system;

determining the respective speed limits for a plurality of upcoming road segments where the vehicle is to travel and in the expected direction of travel by the vehicle and wherein the act of calculating a maximum allowable engine torque is based at least in part upon the respective speed limits for the upcoming road segments.

21. A method according to claim 19 wherein the sub-method A is followed in the event other available sub-methods are not followed.

22. A method according to claim 20 wherein the sub-method A is followed in the event other available sub-methods are not followed, and wherein the sub-method B is followed if there is sufficient information to follow sub-method B and insufficient information to follow sub-methods C or D;

the sub-method C is followed if there is sufficient information follow sub-method C and insufficient information to follow sub-method D; and

the sub-method D is followed if there is sufficient information to follow sub-method D.

23. A method according to claim 19 wherein the available torque limiting sub-methods further comprise sub-method F as set forth below:

F. storing data corresponding to a set of plural different maximum engine torque curves for a plurality of masses of the vehicle, each maximum torque curve being a torque curve associated with a respective one of the plurality of masses of the vehicle;

selecting a maximum engine torque curve corresponding to the mass of the vehicle; and

selectively limiting the maximum torque of the vehicle engine to the selected maximum engine torque for the curve under engine operating conditions wherein the engine is not under the control of a vehicle cruise control system.

24. A computer implemented method of establishing the maximum allowable engine torque for a vehicle comprising:

storing data corresponding to a set of plural different maximum engine torque curves for a plurality of masses of the vehicle, each maximum torque curve being a torque curve associated with a respective one of the plurality of masses of the vehicle;

determining the mass of the vehicle;

selecting a maximum engine torque curve in response to the determined mass of the vehicle; and

selectively limiting the maximum torque of the vehicle engine to the selected maximum engine torque curve under engine operating conditions wherein the engine is not under the control of a vehicle cruise control system.

25. A method according to claim 24 wherein the set of plural maximum engine torque curves comprise a first maximum engine torque curve that is equal to a maximum torque curve for the vehicle at a gross vehicle weight rated load for the vehicle and at least second and third additional maximum torque curves for the vehicle engine at second and third gross vehicle weights that are less than the first maximum engine torque curve.

26. A method according to claim 25 wherein the third maximum torque curve is a maximum torque curve for an unloaded vehicle and the second maximum torque curve is a maximum torque curve for a partially loaded vehicle.

27. A method according to claim 24 wherein the set of plural different maximum torque curves comprises a first maximum torque curve that is equal to a maximum torque curve for the vehicle at a gross vehicle weighted load for the vehicle and at least one other maximum torque curve for a vehicle having a determined mass corresponding to the vehicle being at a mass that is other than the gross vehicle weighted load for the vehicle, and wherein the act of selecting a maximum engine torque curve comprises selecting a maximum torque curve for the determined mass of the vehicle by interpolating or extrapolating between said maximum torque curves for which corresponding data has been stored in the event the determined mass of the vehicle is not indicative of the mass of the vehicle for one of the maximum torque curves for which corresponding data has been stored.

28. A method according to claim 24 comprising determining the slope of the upcoming road on which the vehicle is to travel and selectively adjusting the selected maximum engine torque curve based on the slope of the road and the determined mass of the vehicle.

29. A method according to claim 28 comprising selectively adjusting the selected engine torque curve upwardly to increase the maximum torque values of the selected maximum torque curve if the slope is increasing and the selected engine torque curve is not adjusted to be above the maximum engine torque curve for the gross vehicle weight rated load of the vehicle and downwardly to decrease the torque values of the selected torque curve if the slope is decreasing.

30. A method according to claim 24 further comprising allowing the maximum torque permitted by the maximum allowable torque curve for a vehicle with a gross vehicle weight rated load for an acceleration override time in response to a maximum acceleration request input, wherein the maximum acceleration request input is determined by the position of a driver controlled kickdown switch.

31. A method according to claim 30 comprising changing the duration of the acceleration override time based upon the history of maximum acceleration request inputs.

32. A method according to claim 31 comprising the act of storing the number of maximum acceleration request inputs to create a history of maximum acceleration request inputs in an override evaluation time interval, the method also comprising the act of reducing the duration of the acceleration override time in the event the number of maximum acceleration request inputs in an override evaluation time interval have exceeded a threshold.

33. A method according to claim 30 comprising the act of limiting the torque to the torque of the selected maximum engine torque curve occurs in the absence of one or more of the following exceptions:

a maximum acceleration request input, or the engine speed is below a low speed threshold.

34. An apparatus for establishing the maximum allowable engine torque for a vehicle comprising:

a processor programmed with computer executable instructions and responsive to a first signal corresponding to the mass of the vehicle, a second signal corresponding to the slope of the upcoming road on which the vehicle is to travel, to external parameter signals corresponding to parameters external to the vehicle and to internal parameter signals corresponding to parameter conditions internal to the operation of the vehicle, and operable in response to said first, second, external parameter and internal parameter signals to calculate a maximum allowable engine torque for the engine of the vehicle using longitudinal dynamics equations for the vehicle and based at least in part upon the mass of the vehicle and the slope of the road on which the vehicle is to travel; and

the processor being operable to produce an output that controls the fueling of the engine to selectively limit the maximum torque of the vehicle engine to the calculated maximum allowable torque under engine operating conditions wherein the engine is not under the control of a vehicle cruise control system.

35. An apparatus according to claim 34 comprising a GPS receiver and a 3-dimensional map database coupled to the processer to provide the second signal corresponding to the slope of the upcoming road.

36. An apparatus according to claim 35 wherein the processor is programmed to predictively determine the slope of the road for a plurality of upcoming road segments where the vehicle is to travel and in the expected direction of travel by the vehicle.

37. An apparatus according to claim 36 wherein the processor is programmed to be responsive to speed limit data corresponding to speed limits associated with the plurality of upcoming road segments where the vehicle is to travel and in the expected direction of travel by the vehicle and is operable to calculate a maximum allowable engine torque based at least in part upon the respective speed limit for the upcoming road segments.

38. An apparatus according to claim 34 wherein the internal and external parameter signals correspond to parameters comprising:

39. An apparatus for establishing the maximum allowable engine torque for a vehicle comprising:

means for determining the mass of the vehicle;

means for determining the slope of the upcoming road on which the vehicle is to travel;

means for calculating a maximum allowable engine torque for the engine of the vehicle using longitudinal dynamics equations for the vehicle and based at least in part upon the mass of the vehicle and the slope of the road on which the vehicle is to travel; and

means for selectively limiting the maximum torque of the vehicle engine to the calculated maximum allowable torque under engine operating conditions wherein the engine is not under the control of a vehicle cruise control system.