Suspension Control Device, Vehicle Comprising Said Device, Production Method Thereof and Associated Program

• US 20080319609A1
• Filed: 09/13/2006
• Published: 12/25/2008
• Est. Priority Date: 09/22/2005
• Status: Active Grant

• Current Assignee: Peugeot Citroen Automobiles SA (Stellantis NV)
• Original Assignee: Peugeot Citroen Automobiles SA (Stellantis NV)
• Inventors: Poilbout, Francois
• Granted Patent: US 8,190,327 B2
• Time in Patent Office: Days
• US Class Current: 701/38
• CPC Class Codes: B60G 17/0165 to an external condition, e.g. rough road surface, side wind
• CPC Class Codes: B60G 17/018 characterised by the use of a specific signal treatment or control method
• CPC Class Codes: B60G 17/01933 Velocity, e.g. relative velocity-displacement sensors
• CPC Class Codes: B60G 2400/0521 Roll rate
• CPC Class Codes: B60G 2400/0522 Pitch rate
• CPC Class Codes: B60G 2400/0531 Roll acceleration
• CPC Class Codes: B60G 2400/0532 Pitch acceleration
• CPC Class Codes: B60G 2400/102 vertical
• CPC Class Codes: B60G 2400/202 Piston speed; Relative velocity between vehicle body and wheel
• CPC Class Codes: B60G 2400/252 vertical
• CPC Class Codes: B60G 2500/10 Damping action or damper
• CPC Class Codes: B60G 2800/91 Suspension Control
• CPC Class Codes: B60G 2800/912 Attitude Control; levelling control
• CPC Class Codes: B60G 3/04 the arm being essentially transverse to the longitudinal axis of the vehicle
• CPC Class Codes: B60G 3/20 all arms being rigid

Abstract

The invention relates to a device for controlling the suspension of the body shell of a motor vehicle. The inventive device comprises a calculator (CSS) which can calculate a control value (ER) for an actuator (M) of a shock absorber (AM) of the suspension (S) as a function of at least one modal body shell speed calculated from a modal body shell acceleration.

The invention is characterised by a sensor (CAP-DEB) for sensing wheel (A, B, C, D) travel in relation to the body shell, which is connected to a first means (CAL) for calculating the modal body shell acceleration from the travel measurement (DEB) provided by the sensor (CAP-DEB).

Claims

1. Suspension control device with variable damping for a motor vehicle body on its wheels, having a computer adapted to calculate a control magnitude of an actuator of at least one damper with variable damping of the suspension as a function of at least one body modal speed, calculated from at least one body modal acceleration determined on the vehicle, wherein the device further comprises at least one sensor of the displacement of a wheel with respect to the vehicle body, connected to a first means for calculating the body modal acceleration from the displacement measurement provided by the displacement sensor.

2. Control device according to claim 1, wherein the first means for calculating the body modal acceleration comprises an estimator of at least one force exerted by the suspension of said wheel on the body as a function of at least the displacement measurement provided by the displacement sensor, and a second means for calculating the body modal acceleration as a function of at least the suspension force provided by said suspension force estimator.

3. Control device according to claim 2, wherein the suspension force estimator comprises:

a derivator module calculating a displacement speed from a displacement measurement (DEB) provided by the displacement sensor,

an estimator of a damping force of the damper as a function of the displacement speed provided by the derivator module and the memorized current damping law of the damper,

an estimator of a dry friction force as a function of the displacement speed,

an estimator of a flexion force of suspension springs and stops of the damper as a function of the displacement value and a determined static attitude of the body.

4. Control device according to claim 3, wherein the estimator of the dry friction force is a hyperbolic tangential or circular tangent function of the displacement speed divided by a fixed value, this function being multiplied by a prescribed multiplying factor.

5. Control device according to claim 3, wherein the estimator of the flexion force of suspension springs and stops comprises:

a module for calculating the static attitude of the vehicle as a function of the displacement value,

an adder for calculating a summed value of the displacement value and the static attitude,

a module for calculating an absolute flexion force of suspension springs and stops of the damper as a function of said summed value,

a module for calculating a static flexion force on said wheel as a function of the static attitude,

a subtractor providing said flexion force of suspension springs and stops by subtracting the static flexion force from the absolute flexion force of suspension springs and stops.

6. Suspension control device according to claim 5, wherein a displacement sensor is provided for each of the two front wheels and the two rear wheels, and the module for calculating the static attitude has a means for calculating the front static attitude and the rear static attitude of the vehicle, as being the mean displacement of the front wheel displacements and the rear wheel displacements, respectively, filtrated by a low-pass filter, a front attitude offset constant and a rear attitude offset constant, respectively, being added to this filtered mean displacement.

7. Control device according to claim 1, wherein the first calculation means further comprises an estimator of a roll torque and/or an estimator of a pitch torque.

8. Control device according to claim 7, wherein the first calculation means has:

a means for calculating a transverse acceleration reset value RECT,

a sensor of the vehicle body transverse acceleration ACCT;

the roll torque estimator calculating said roll torque c_θ

using the formula;

c_θ

=(ACCT−

RECT).(MTOT).d(G,CR)

where MTOT is the vehicle mass, and

d(G, CR) is the predetermined distance between the center of gravity (G) of the body and its roll center (CR).

9. Control device according to claim 7, wherein the first calculation means has:

a means for calculating a longitudinal acceleration reset value RECL,

a sensor of the longitudinal acceleration ACCL of the vehicle body,

the estimator of the pitch torque calculating said pitch torque c_φ

using the formula;

c_φ

=(ACCL−

RECL).(MTOT).hG+C<sub>φ

B</sub>,

where MTOT is the vehicle mass,

hG is the predetermined height between the center of gravity (G) of the body and its pitch center (CT), and

C<sub>φ

B</sub> is the component of the pitch torque attributable to the Brouilhet effect.

10. Control device according to claim 9, wherein the component c_φ

B of the pitch torque attributable to the Brouilhet effect is calculated as a function of a braking information unit provided by a determination module as a function of a master cylinder pressure value provided by a master cylinder pressure sensor.

11. Control device according to claim 1, which comprises a first filter that eliminates at least the low frequencies of the body modal acceleration provided by the first calculation means and a third means for calculating the body modal speed from the filtered body modal acceleration provided by the first filter.

12. Control device according to claim 11, wherein the low cutoff frequency of the first filter is greater than or equal to 0.1 Hz.

13. Control device according to claim 1, wherein the first means for calculating the body modal acceleration comprises a second filter that eliminates at least the low frequencies from the displacement measurement provided by the displacement sensor.

14. Control device according to claim 13, wherein the low cutoff frequency of the second filter is greater than or equal to 0.2 Hz.

15. Control device according to claim 1, wherein the control magnitude is a damping law determined from a plurality of different damping laws that impose the damper force as a function of its displacement speed.

16. Motor vehicle having a body, wheels, a suspension of the body on the wheels, and a suspension control device according to claim 1.

17. Production method for a motor vehicle,

the motor vehicle being equipped with wheels, a body, a suspension having at least one damper with variable damping of the body on the wheels, and a suspension control device, the control device having at least one computer adapted to calculate a control magnitude of an actuator of said at least one suspension damper,

the production method having a step in which the computer is mounted on the vehicle,

wherein the production method has

at least one computer programming step using at least one program having program instructions that employ the calculating means of the suspension control device according to claim 1.

18. Computer program for controlling a computer, having program instructions for calculating the body modal acceleration from the displacement measurement provided by the wheel displacement sensor, for calculating the body modal velocity as a function of at least this body modal acceleration, and for calculating the control magnitude of the actuator as a function of this body modal speed, when it is employed in a suspension control device according to claim 1.