Method to control a road vehicle with a microslip of the clutch

Patent metadata

Field	Value
Publication number	US-11248667-B2
Application number	US-202017026693-A
Country	US
Kind code	B2
Filing date	Sep 21, 2020
Priority date	Sep 30, 2019
Publication date	Feb 15, 2022
Grant date	Feb 15, 2022

Abstract

A method to control a road vehicle provided with a clutch, which connects an internal combustion engine to drive wheels and is arranged upstream of a servo-assisted transmission; the control method comprises the steps of: checking whether the tyres of the drive wheels are close to a grip limit; and opening the clutch so that the clutch transmits a torque to the drive wheels with a slip of the clutch that is constant and other than zero when the tyres of the drive wheels are close to the grip limit.

First claim

The invention claimed is:

1. A method to control a road vehicle ( 1 ) provided with a clutch ( 16 ), which connects an internal combustion engine ( 4 ) to drive wheels ( 3 ) and is arranged upstream of a servo-assisted transmission ( 7 ); the control method comprises the steps of:
checking whether tyres of the drive wheels ( 3 ) are close to a grip limit; and
opening the clutch ( 16 ) so that the clutch ( 16 ) transmits a torque to the drive wheels ( 3 ) with a slip of the clutch ( 16 ) that is constant and other than zero when the tyres of the drive wheels ( 3 ) are close to the grip limit;
wherein the tyres of the drive wheels ( 3 ) are considered close to the grip limit if: in the servo-assisted transmission ( 7 ), a gear is engaged, which belongs to a predetermined set of gears; and a torque (T E ) generated by the internal combustion engine ( 4 ) exceeds a torque threshold value.

2. The control method according to claim 1 , wherein, due to the slip, a driving disc ( 26 ) of the clutch ( 16 ) has a rotation speed (ω 1 ) which is greater than a rotation speed (ω 2 ) of a driven disc ( 27 ) of the clutch ( 16 ).

3. The control method according to claim 2 , wherein a difference between the rotation speed (ω 1 ) of the driving disc ( 26 ) and the rotation speed (ω 2 ) of the driven disc ( 27 ) ranges from 70 to 180 revolutions/minute.

4. The control method according to claim 2 , wherein a difference between the rotation speed (ω 1 ) of the driving disc ( 26 ) and the rotation speed (ω 2 ) of the driven disc ( 27 ) ranges from 0.5% to 1.2% of a rotation speed (ω E ) of the internal combustion engine ( 4 ).

5. The control method according to claim 1 , wherein the tyres of the drive wheels ( 3 ) are also considered close to the grip limit if a rotation speed (ω E ) of the internal combustion engine ( 4 ) is comprised in a predetermined range of speeds.

6. The control method according to claim 1 and comprising the further steps of:
determining a degree of grip of a road surface on which the road vehicle ( 1 ) rests; and
determining the torque threshold value depending on the degree of grip of the road surface.

7. The control method according to claim 1 and comprising the further steps of:
determining a target slip (S T ) of the clutch ( 16 );
detecting an engine torque (T E ) generated by the internal combustion engine ( 4 );
establishing a clutch torque (T C ), which has to be transmitted by the clutch ( 16 ); and
controlling the clutch ( 16 ) so as to transmit the clutch torque (T C ).

8. The control method according to claim 7 , wherein the target slip (ω E ) of the clutch ( 16 ) is read from a memory of a control unit ( 12 ) of the drivetrain ( 6 ).

9. The control method according to claim 7 and comprising the further steps of:
cyclically determining a real slip of the (S R ) of the clutch ( 16 );
establishing the clutch torque (T C ), which has to be transmitted by the clutch ( 16 ) and is smaller than the engine torque (T E ); and
cyclically changing the clutch torque (T C ) depending on a difference between the target slip (S T ) of the clutch ( 16 ) and the real slip of the (S R ) of the clutch ( 16 ).

10. The control method according to claim 9 , wherein the clutch torque (T C ) is changed so as to pursue the target slip (S T ) of the clutch ( 16 ).

11. The control method according to claim 9 , wherein the clutch torque (T C ) is modulated by means of a feedback control in which a control error (ε S ) is the difference between the target slip (S T ) of the clutch ( 16 ) and the real slip of the (S R ) of the clutch ( 16 ).

12. The control method according to claim 11 , wherein the clutch torque (T C ) is changed by a PID controller ( 29 ) which receives, as an input, the control error (ε S ).

13. The control method according to claim 7 and comprising the further steps of:
establishing the clutch torque (T C ), which has to be transmitted by the clutch ( 16 ) and is equal to the engine torque (T E );
detecting a rotation speed (ω 2 ) of a driven disc ( 27 ) of the clutch ( 16 );
determining a target rotation speed (ω 1-T ) of a driving disc ( 26 ) of the clutch ( 16 ) by adding the target slip (S T ) of the clutch ( 16 ) to the rotation speed (ω 2 ) of the driven disc ( 27 ) of the clutch ( 16 ); and
controlling the internal combustion engine ( 4 ) so as to change the engine torque (T E ) generated by the internal combustion engine ( 4 ) so as to pursue the target rotation speed (ω 1-T ) of a driving disc ( 26 ) of the clutch ( 16 ).

Assignees

• Ferrari Spa

Inventors

• Barone Alessandro
• Nannini Andrea
• Senserini Giacomo
• Marconi Stefano

Classifications

• B60W30/19 Primary

  Improvement of gear change, e.g. by synchronisation or smoothing gear shift · CPC title

• F16H57/0006

  Vibration-damping or noise reducing means specially adapted for gearings (devices for varying tension of belts, ropes or chains with damping means F16H7/0829; toothed members with construction providing vibration damping F16H55/14; reducing vibrations or noise of the gearbox casing F16H57/028; suppression of vibrations or noise of gear selectors F16H59/0208; control of hydrostatic fluid gearing preventing or reducing vibrations or noise F16H61/4183) · CPC title

• F16H2059/465

  Detecting slip, e.g. clutch slip ratio · CPC title

• B60W10/06

  including control of combustion engines · CPC title

• F16D48/06 Primary

  Control by electric or electronic means, e.g. of fluid pressure · CPC title