METHOD TO CONTROL TOE ANGLE AND CAMBER ANGLE IN ACTIVE REAR SUSPENSIONS OF CARS

• US 20130190980A1
• Filed: 01/04/2013
• Published: 07/25/2013
• Est. Priority Date: 01/05/2012
• Status: Active Grant

• Current Assignee: Ferrari S. P. A.
• Original Assignee: Ferrari SPA (Stellantis NV)
• Inventors: Ramirez Ruiz, Isabel
• Granted Patent: US 9,216,625 B2
• Time in Patent Office: Days
• US Class Current: 701/38
• CPC Class Codes: B60G 17/0162 mainly during a motion involving steering operation, e.g. cornering, overtaking B60G17/0164 takes precedence
• CPC Class Codes: B60G 17/0163 the control involving steering geometry, e.g. four-wheel steering
• CPC Class Codes: B60G 17/0164 mainly during accelerating or braking
• CPC Class Codes: B60G 17/0182 involving parameter estimation, e.g. observer, Kalman filter
• CPC Class Codes: B60G 2200/46 camber angle
• CPC Class Codes: B60G 2200/4622 Alignment adjustment
• CPC Class Codes: B60G 2204/62 Adjustable continuously, e.g. during driving
• CPC Class Codes: B60G 2401/16 GPS track data
• CPC Class Codes: B60G 2401/28 Gyroscopes
• CPC Class Codes: B60G 2800/22 Braking, stopping
• CPC Class Codes: B60G 2800/24 Steering, cornering
• CPC Class Codes: B60G 2800/962 Four-wheel steering
• CPC Class Codes: B60G 7/003 of adjustable length
• CPC Class Codes: B62D 17/00 Means on vehicles for adjusting camber, castor, or toe-in

Abstract

A control method of the toe and camber angles of rear active suspensions of a vehicle; the control method includes the steps of:

• • detecting when the vehicle follows a curved trajectory; conferring negative toe angles combined with zero camber angles to the rear active suspensions, when starting the curved trajectory and when the vehicle enters the curved trajectory; and conferring positive camber angles combined with negative toe angles to the rear active suspensions, while following the curved trajectory and when the vehicle is inscribed in the curved trajectory.

Claims

1. ) A control method of the toe and camber angles of rear active suspensions (12) or a vehicle (1);

the control method comprises the steps of;

detecting when the vehicle (1) follows a curved trajectory (T); and

conferring negative camber angles to the rear active suspensions (12), while following the curved trajectory (T) and when the vehicle (1) is inscribed in the curved trajectory (T);

the control method is characterized in that it comprises the further steps of;

conferring negative toe angles combined with zero camber angles to the rear active suspensions (12), when starting the curved trajectory (T) and when the vehicle (1) enters the curved trajectory (T); and

conferring positive camber angles combined with negative toe angles to the rear active suspensions (12), while following the curved trajectory (T) and when the vehicle (1) is inscribed in the curved trajectory (T).

2. ) A control method according to claim 1 and comprising the further step of differentiating, when the vehicle (1) follows a curved trajectory (T), the toe and/or camber angles of the inner rear suspension (12i) of the corner from the toe and/or camber angles of the outer rear suspension (12e) of the corner.

3. ) A control method according to claim 2 and comprising the further steps of:

conferring, when the vehicle (1) follows a curved trajectory (T), negative values close to zero to the camber angle of the inner rear suspension (12i) of the corner; and

conferring, when the vehicle (1) follows a curved trajectory (T), second negative values, higher in absolute terms that the first negative values, to the camber angle of the outer rear suspension (12i) of the corner.

4. ) A control method according to claim 1 and comprising the further steps of:

gradually decreasing, while following the curved trajectory (T) and when the vehicle (1) is inscribed in the curved trajectory (T), the absolute value of the positive toe angles of the rear active suspensions (12) little-by-little as the tires approach their grip limit; and

gradually increasing, while following the curved trajectory (T) and when the vehicle (1) is inscribed in the curved trajectory (T), the absolute value of the negative camber angles of the rear active suspensions (12) as the corresponding tires approach their grip limit.

5. ) A control method according to claim 1 and comprising the further steps of:

gradually decreasing, while following the curved trajectory (T) and when the vehicle (1) is inscribed in the curved trajectory (T), the absolute value of the positive toe angle of the outer rear suspension (12e) of the corner as the tire approaches the grip limit; and

gradually increasing, while following the curved trajectory (T) and when the vehicle (1) is inscribed in the curved trajectory (T), the absolute value of the negative camber angle of the outer rear suspension (12e) of the corner as the corresponding tire approaches the grip limit.

6. ) A control method according to claim 5 and comprising the further step of maintaining essentially constant, while following the curved trajectory (T) and when the vehicle is inscribed in the curved trajectory (1), the toe and camber angles of the inner rear suspension (12i) of the corner as the corresponding tire approaches the grip limit.

7. ) A control method according to claim 1 and comprising the further step of:

detecting when the vehicle (1) follows a curved trajectory (T) for performing a change of trajectory on a straight line;

determining the sideslip angle (β

) of the vehicle (1), i.e. the angle comprised between the longitudinal axis of the vehicle (1) and the direction of the velocity (V) of the vehicle (1) in its centre of gravity (B), which is positive when the tail-end of the vehicle (1) is inside the trajectory of the centre of gravity (B) and is negative when the tail-end of the vehicle (1) is outside the trajectory of the centre of gravity (B); and

conferring, when the vehicle (1) follows a curved trajectory (T) to perform a change of trajectory on a straight line and the sideslip angle (β

) is positive, negative values such as to cancel the positive sideslip angle (β

) of the vehicle (1) to the toe angle of the rear active suspensions (12).

8. ) A control method according to claim 1 and comprising a further step of conferring, when exiting from the curved trajectory (T) and when the vehicle (1) is accelerating, zero toe angles combined with negative camber angles to the rear active suspensions (12).

9. ) A control method according to claim 1 and comprising the further step of conferring, when the vehicle (1) brakes on a straight line, nearly zero toe angles combined with negative camber angles to the rear active suspensions (12).

10. ) A control method according to claim 1 and comprising the further step of conferring, when the vehicle (1) accelerates on a straight line, positive, low value toe angles combined with zero camber angles to the rear active suspensions (12).