Slip loss reduction control system for improving driveline efficiency

• US 20060173603A1
• Filed: 12/12/2005
• Published: 08/03/2006
• Est. Priority Date: 02/02/2005
• Status: Abandoned Application

• Current Assignee: Magna Powertrain Incorporated (Magna International Incorporated)
• Original Assignee: Magna Powertrain Incorporated (Magna International Incorporated)
• Inventors: Mohan, Sankar K., Sharma, Anupam, Bansbach, Eric A.
• Application Number:
  US11/301,084
• Publication Number:
  US 20060173603A1
• Time in Patent Office: Days
• US Class Current: 701/71
• CPC Class Codes: B60K 28/16 responsive to, or preventing, skidding of wheels brake control systems for vehicle drive stability B60T8/1755; arrangements responsive to a speed condition for adjusting wheel braking force B60T8/32; control of vehicle driving stability otherwise than by controlling the propulsion unit only B60W30/02; preventing wheel slippage by reducing power in rail vehicles B61C15/00
• CPC Class Codes: B60T 2210/12 Friction
• CPC Class Codes: B60T 2240/06 Wheel load; Wheel lift
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence
• CPC Class Codes: B60T 8/1755 Brake regulation specially adapted to control the stability of the vehicle, e.g. taking into account yaw rate or transverse acceleration in a curve road vehicle drive control systems for control of driving stability otherwise than by controlling a particular sub-unit B60W30/02
• CPC Class Codes: B60T 8/17616 Microprocessor-based systems
• CPC Class Codes: B60W 2520/26 Wheel slip
• CPC Class Codes: B60W 2530/20 Tyre data
• CPC Class Codes: B60W 2720/30 Wheel torque

Abstract

A method is provided for reducing slip loss experienced by the tires of a vehicle. The method includes: determining a longitudinal force associated with each tire; determining an optimal slip coefficient for each tire based in part on the corresponding longitudinal force for the tire; and determining a torque to be applied to each tire based in part on the optimal slip coefficient, thereby reducing the slip loss experienced by the tires of the vehicle. This method is typically employed in the absence of other control algorithms used by a vehicle'"'"'s traction control system.

Claims

1. A method for reducing slip loss experienced by the tires of a vehicle, comprising:

determining a longitudinal force associated with each tire;

determining an optimal slip coefficient for each tire based in part on the corresponding longitudinal force for the tire; and

determining a torque to be applied to each tire based in part on the optimal slip coefficient, thereby reducing the slip loss experienced by the tires of the vehicle.

2. The method of claim 1 wherein determining a longitudinal force further comprises:

estimating a friction coefficient between the tires of the vehicle and a driving surface being traversed by the vehicle;

determining a vertical force exerted on each tire; and

multiplying the friction coefficient by the vertical force for a given tire to determine the longitudinal force for the given tire.

3. The method of claim 2 wherein the friction coefficient is estimated using a Pacejka tire model.

4. The method of claim 1 wherein slip efficiency for the tires of the vehicle is defined by a function as

$\eta$

= 1 - ∑

1 4 ⁢

F xi ⁢

σ

i 1 - σ

i ∑

1 4 ⁢

F xi 1 - σ

i

where F_x is the longitudinal force associated with a given tire and σ

is a slip coefficient for the given tire, such that minimizing the function yields the optimal slip coefficient for the given tire.

5. The method of claim 1 wherein determining a torque for a given wheel, T_i, is calculated in accordance with

T_i=σ

_ih_iK_iF_ziμ

_max

where σ

_i is the optimal slip coefficient for the given wheel, h_i is the load radius for the tire on the given wheel, K_i correlates to elastic properties of the tire of the given wheel, F_zi is the vertical force on the given wheel, and μ

_maxi is an actual value of the road friction coefficient at the tire patch of the given wheel.

6. A method for improving driveline efficiency of a vehicle having an active traction control system, comprising:

monitoring driving conditions during vehicle operation;

performing a vehicle safety action using the traction control system in response to a hazardous driving conditions; and

reducing slip loss experienced by the tires of the vehicle during non-hazardous driving conditions.

7. The method of claim 7 wherein reducing slip loss further comprises

determining a longitudinal force associated with each tire;

determining an optimal slip coefficient for each tire based in part on the corresponding longitudinal force for the tire; and

determining a torque to be applied to each tire based in part on the optimal slip coefficient, thereby reducing the slip loss experienced by the tires of the vehicle.

12. The method of claim 7 wherein the vehicle safety action is further defined as maximizing tractive force at each tire patch without compromising lateral stability.

13. The method of claim 7 wherein the vehicle safety action is further defined as varying tractive force at each tire to provide a yaw moment correction needed to maintain a driver'"'"'s intended vehicle direction.

8. The method of claim 8 wherein determining a longitudinal force further comprises:

estimating a friction coefficient between the tires of the vehicle and a driving surface being traversed by the vehicle;

determining a vertical force exerted on each tire; and

multiplying the friction coefficient by the vertical force for a given tire to determine the longitudinal force for the given tire.

10. The method of claim 8 wherein slip efficiency for the tires of the vehicle is defined by a function as

$\eta$

= 1 - ∑

1 4 ⁢

F xi ⁢

σ

i 1 - σ

i ∑

1 4 ⁢

F xi 1 - σ

i

where F_x is the longitudinal force associated with a given tire and σ

is a slip coefficient for the given tire, such that minimizing the function yields the optimal slip coefficient for the given tire.

11. The method of claim 8 wherein determining a torque for a given wheel, T_i, is calculated in accordance with

T_i=σ

_ih_iK_iF_ziμ

maxi

where σ

_i is the optimal slip coefficient for the given wheel, h_i is the load radius for the tire on the given wheel, K_i correlates to elastic properties of the tire of the given wheel, F_zi is the vertical force on the given wheel, and μ

_maxi is an actual value of the road friction coefficient at the tire patch of the given wheel.

9. The method of claim 9 wherein the friction coefficient is estimated using a Pacejka tire model.