Curve-dependent engine drag-torque control

• US 20030221889A1
• Filed: 03/27/2003
• Published: 12/04/2003
• Est. Priority Date: 03/27/2002
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Sauter, Thomas
• Granted Patent: US 6,952,638 B2
• Time in Patent Office: Days
• US Class Current: 180/197
• 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 2201/09 Engine drag compensation
• CPC Class Codes: B60W 2540/18 Steering angle
• 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 2552/30 Road curve radius
• CPC Class Codes: B60W 2552/40 Coefficient of friction
• CPC Class Codes: F02D 2250/26 by applying a torque limit

Abstract

An engine drag-torque control, particularly for motor vehicles, in which the engine torque is increased by an EDC augmenting torque when the driven wheels drop below a slip threshold due to the braking action of the engine and exhibit a brake slip which is too high. To improve the vehicle control during cornering on a roadway having a low coefficient of friction, it is provided to increase the slip threshold for the driven wheels to thereby set the drag-torque control to be more sensitive.

Claims

1. An engine drag-torque control for a motor vehicle comprising:

means for detecting curves and coefficients of friction; and

an arrangement for increasing the torque of an engine when at least one driven wheel falls below a slip threshold due to a braking action of the engine, the arrangement increasing the slip threshold for at least one driven wheel in response to cornering on a roadway having a low coefficient of friction.

2. The engine drag-torque control according to claim 1, wherein, in response to wheel slip because of a downshift operation, the engine torque is increased by a boosted augmenting torque which is greater than an augmenting torque in response to releasing an accelerator.

3. The engine drag-torque control according to claim 1, wherein, in response to wheel slip because of a downshift operation, an amplified rotary acceleration moment of resistance is calculated.

4. The engine drag-torque control according to claim 3, wherein the amplified rotary acceleration moment of resistance is restricted to a maximum value.

5. The engine drag-torque control according to claim 1, wherein the engine torque is increased by at least a minimum augmenting torque.

6. The engine drag-torque control according to claim 1, wherein, after the driven wheel has exceeded the slip threshold again, the arrangement continues an engine-drag torque control for a predefined follow-up time, and during the follow-up time, a follow-up augmenting torque is generated.

7. The engine drag-torque control according to claim 2, wherein the augmenting torque added in response to wheel slip because of a downshift operation is calculated as a function of which gear was downshifted to.

8. A method for engine drag-torque control for a motor vehicle, the engine torque being increased when at least one driven wheel drops below a slip threshold due to a braking action of the engine and exhibits a brake slip which is too high, the method comprising:

determining whether the vehicle is cornering;

ascertaining a coefficient of friction of a roadway; and

raising the slip threshold for at least one driven wheel if cornering was detected on a roadway having a low coefficient of friction.

9. The method according to claim 8, further comprising calculating a boosted augmenting torque in response to wheel slip because of a downshift operation.

10. The method according to claim 8, wherein the engine torque is increased by at least a minimum augmenting torque.

11. The method according to claim 8, further comprising:

continuing an engine drag-torque control for a predefined follow-up time after the slip threshold has been exceeded; and

predefining a follow-up augmenting torque during the follow-up time.