Torque control method of a road vehicle

• US 8,135,517 B2
• Filed: 07/24/2008
• Issued: 03/13/2012
• Est. Priority Date: 07/25/2007
• Status: Expired due to Fees

• Current Assignee: Magneti Marelli Powertrain S.p.A. (Magneti Marelli S.p.A.)
• Original Assignee: Magneti Marelli Powertrain S.p.A. (Magneti Marelli S.p.A.)
• Inventors: Lupo, Savino Luigi, Serra, Gabriele, Para, Filippo
• Primary Examiner(s): Tran, Khoi
• Assistant Examiner(s): Sample, Jonathan L
• Application Number:
  US12/179,292
• Publication Number:
  US 20090093937A1
• Time in Patent Office: 1,328 Days
• Field of Search: None
• US Class Current: 701/48
• CPC Class Codes: B60W 2050/0031 Mathematical model of the vehicle
• CPC Class Codes: B60W 2050/0041 of the drive line
• CPC Class Codes: B60W 30/20 Reducing vibrations in the driveline
• CPC Class Codes: F02D 2041/1433 using a model or simulation of the system
• CPC Class Codes: F02D 2200/1004 Estimation of the output torque
• CPC Class Codes: F02D 2250/18 Control of the engine output torque
• CPC Class Codes: F02D 2250/28 Control for reducing torsional vibrations, e.g. at acceleration
• CPC Class Codes: F02D 41/021 Introducing corrections for particular conditions exterior to the engine conjoint control of vehicle sub-units for propelling the vehicle B60W30/18
• CPC Class Codes: F02D 41/1497 With detection of the mechanical response of the engine
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

A control method of the torque of a road vehicle having a powertrain system provided with an engine and a driveline which transmits the torque generated by the engine to the road surface; the method contemplates the steps of: determining a target torque; modeling the powertrain system as a single physical component which presents a characteristic mechanical inertia and a characteristic torsional elasticity; determining a current load torque of the vehicle; determining a target torsion of the powertrain system according to the target torque and the current load torque; determining a current torsion of the powertrain system and a current torsion speed of the powertrain system; determining a requested torque on the basis of the energy balance according to the target torsion, the current torsion, the current torsion speed, and the current load torque; and using the requested torque on the basis of the energy balance to control the torque generation of the engine.

Claims

1. A control method of the torque of a road vehicle comprising a powertrain system provided with an engine presenting a drive shaft and a driveline which transmits the torque generated by the engine to the road surface through the drive wheels;

the method comprises the steps of;

determining a target torque (T_e-targ); and

controlling the generation of torque by the engine on the basis of the target torque (T_e-targ);

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

modeling the powertrain system as a single physical component which presents a characteristic mechanical inertia and a characteristic torsional elasticity and which must undergo a corresponding torsion to transmit a certain drive torque;

determining a current load torque (T_r) of the vehicle;

determining a target torsion (Δ

θ

_targ) of the powertrain system according to the target torque (T_e-targ) and the current load torque (T_r);

determining a current torsion (Δ

θ

) of the powertrain system and a current torsion speed (Δ

θ

′

) of the powertrain system;

determining a requested torque (T_e-EC) on the basis of the energy balance according to the target torsion (Δ

θ

_targ), the current torsion (Δ

θ

), the current torsion speed (Δ

θ

′

), and the current load torque (T_r); and

using the requested torque (T_e-EC) on the basis of the energy balance to control the torque generation of the engine.

2. A method according to claim 1, wherein the target torsion (Δ

θ

_targ) is calculated by means of the following equation;

3. A method according to claim 1, wherein the requested torque (T_e-EC) on the basis of the energy balance is calculated by means of the following equation:

4. A method according to claim 3, wherein the function E(Δ

θ

,Δ

θ

′

) which renders the total mechanical energy of the powertrain system is based on the following equation;

5. A method according to claim 3, wherein the requested torque (T_e-EC) on the basis of the energy balance is determined only when the difference between the target torsion (Δ

θ

_targ) is significantly different from the current torsion (Δ

θ

) and the current torsion speed (Δ

θ

′

) is significantly different from zero and thus outside the singularity zone (I) indicated by the following expression;

(Δ

θ

,Δ

θ

′

)ε

I,I≡

{(Δ

θ

,Δ

θ

′

);

|Δ

θ

_targ−

Δ

θ

|<

Θ

_switch,|Δ

θ

′

|<

Ψ

_switch}

Δ

θ

current torsion of the powertrain system transmitted to the drive shaft [rad];

Δ

θ

′

current torsion speed of the powertrain system transmitted to the drive shaft [rad/s];

Δ

θ

_targ target torsion of the powertrain system [rad];

Θ

_switch first threshold value;

Ψ

_switch second threshold value.

6. A method according to claim 5, and comprising the further steps of:

determining, within the singularity zone (I), a requested torque (T_e-CL) on the basis of the maximum damping; and

using the requested torque (T_e-CL) on the basis of the maximum damping to control the generation of engine torque (4).

7. A method according to claim 6, wherein the requested torque (T_e-CL) on the basis of the maximum damping is calculated by means of the following equation:

T_e-CL=T_e-targ−

G_i·

Δ

θ

′

T_e-CL requested torque on the basis of the maximum damping [Nm];

T_e-targ target torque [Nm];

G_i damping constant;

Δ

θ

′

current torsion speed of the powertrain system transmitted to the drive shaft [rad/s].

8. A method according to claim 6, and comprising the further steps of:

using the requested torque (T_e-EC) on the basis of the energy balance to control the torque generation of the engine during the first instants of a transient triggered during a change of the target torque (T_e-targ);

using the requested torque (T_e-EC) on the basis of the maximum damping to control the torque generation of the engine when the transient triggered by a change of the target torque (T_e-targ) is close to being exhausted; and

using the target torque (T_e-targ) for controlling the torque generation of the engine when the transient triggered by a change of the target torque (T_e-targ) is exhausted.

9. A method according to claim 1 and comprising the further step of determining the current torsion (Δ

θ

), the current torsion speed (Δ

θ

′

), and the current load torque (T_r) by means of an observer (23) which receives as input an effective torque (T_e) generated by the engine and a number (N) of revolutions of the engine.

10. A method according to claim 1 and comprising the further steps of:

determining a torque (T_e-rqst) requested by a driver or by an automatic cruise control;

limiting the requested torque (T_e-rqst) within a range, which comprises a minimum torque (T_min) and maximum torque (T_max) and takes the physical limits of the engine into account;

filtering the limited requested torque (T_e-rqst) by means of a low-pass type filter to obtain a requested and filtered torque (T_fil); and

determining the target torque (T_e-targ) as the maximum between the requested and filtered torque (T_fil) and an idling torque (T_idle).