Method and Sytem for Controlling Start-Up of a Motor Vehicle by Dialogue of the Engine Controlling Computer with the Piloted Mechanical Gearbox, During Restart of the Vehicle in Stop and Start Mode

• US 20080318731A1
• Filed: 03/31/2006
• Published: 12/25/2008
• Est. Priority Date: 04/06/2005
• Status: Active Grant

• Current Assignee: Peugeot Citroen Automobile SA (Stellantis NV)
• Original Assignee: Peugeot Citroen Automobile SA (Stellantis NV)
• Inventors: Denis, Jean-Christophe
• Granted Patent: US 7,881,835 B2
• Time in Patent Office: Days
• US Class Current: 477/99
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/11 Stepped gearings
• CPC Class Codes: B60W 2510/0652 Speed change rate
• CPC Class Codes: B60W 2510/0676 Engine temperature
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2540/103 Accelerator thresholds, e.g. kickdown
• CPC Class Codes: B60W 30/18018 Start-stop drive, e.g. in a traffic jam
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

The invention concerns a method and a system for controlling start-up of a motor vehicle by dialogue of the engine controlling computer with the piloted mechanical gearbox, during a restart of the vehicle in stop and start mode. A “start-up authorization” is transmitted to the gearbox at a time t when the following three conditions are fulfilled: a) verifying the position of the accelerator pedal relative to a predetermined “threshold” position; b) the engine is in sequential injection phase; c) verifying a so-called “autonomous condition”, calculated on the basis of the engine speed and of an engine speed gradient compared to a predetermined threshold value. The invention is applicable to motor vehicles.

Claims

1. Start-off control method for a motor vehicle using dialogue between the engine control computer and the electronically controlled mechanical gearbox when restarting the vehicle in stop-and-start mode, wherein said method comprises the following steps:

verifying whether the position of the accelerator pedal (Alpha pedal) is higher than a predetermined “

threshold”

position (Threshold S_Alpha);

verifying whether the engine is in sequential injection mode;

verifying whether the engine speed gradient with respect to time (dN/dt) at instant t is higher than a predetermined threshold value (Grad_N_dem) based on the engine speed, this condition being called the “

autonomous condition”

;

and if the three conditions are fulfilled, a “

start-off authorization”

is transmitted to the gearbox.

2. Method according to claim 1, wherein during the verification step for the autonomous condition, if this condition is not met, the method includes the step of controlling fuel injection for a time interval until said autonomous condition is met.

3. Method according to claim 1, wherein verifying said autonomous condition at an instant entails the following steps:

calculating the engine speed (N) at instant t;

calculating the value of the engine speed gradient with respect to time (dN/dt) at instant t;

and comparing the value of said engine speed gradient with respect to time with a predetermined engine speed gradient threshold value (Grad_N_dem) based on the engine speed;

the autonomous conditions being met if the value of the engine speed gradient with respect to time (dN/dt) is higher than said predetermined engine speed gradient threshold value (Grad_N_dem) based on the engine speed.

4. Method according to claim 3, wherein said predetermined engine speed gradient threshold value (Grad_N_dem) based on the engine speed is obtained by the following formula:

K_Grad_N_dem(T_WATER)*Grad_N_dem(K_N_dem(T_WATER)*N_common),

in which;

Grad_N_dem is a predetermined threshold value based on the engine speed;

K_Grad_N_dem is a gain factor based on water temperature;

K_N_dem(T_WATER) is a correction factor based on water temperature;

T_WATER is water temperature;

and N_common is the average speed over a half-rotation of the engine, calculated by the engine control computer.

5. Method according to claim 1, wherein the result of comparing the value of the engine speed gradient with respect to time with a predetermined threshold value based on the engine speed is validated after a time delay (Tempo_cond_dem).

6. Method according to claim 1, wherein the engine speed gradient with respect to time (dN/dt) is determined from the current engine speed and the engine speed at time step (n−

1), initialized at zero.

7. Method according to claim 1, wherein the “

threshold”

position of the accelerator pedal (Threshold S_Alpha) is a predetermined angular value that can be calibrated.

10. Method according to claim 2, wherein verifying said autonomous condition at an instant t entails the following steps:

calculating the engine speed (N) at instant t;

calculating the value of the engine speed gradient with respect to time (dN/dt) at instant t;

and comparing the value of said engine speed gradient with respect to time with a predetermined engine speed gradient threshold value (Grad_N_dem) based on the engine speed;

the autonomous condition being met if the value of the engine speed gradient with respect to time (dN/dt) is higher than said predetermined engine speed gradient threshold value (Grad_N_dem) based on the engine speed.

11. Method according to claim 10, wherein said predetermined engine speed gradient threshold value (Grad_N_dem) based on the engine speed is obtained by the following formula:

K_Grad_N_dem(T_WATER)*Grad_N_dem(K_N_dem(T_WATER)*N_common),

in which;

Grad_N_dem is a predetermined threshold value based on the engine speed;

K_Grad_N_dem is a gain factor based on water temperature;

K_N_dem(T_WATER) is a correction factor based on water temperature;

T_WATER is water temperature;

and N_common is the average speed over a half-rotation of the engine, calculated by the engine control computer.

12. Method according to claim 2, wherein the result of comparing the value of the engine speed gradient with respect to time with a predetermined threshold value based on the engine speed is validated after a time delay (Tempo_cond_dem).

13. Method according to claim 3, wherein the result of comparing the value of the engine speed gradient with respect to time with a predetermined threshold value based on the engine speed is validated after a time delay (Tempo_cond_dem).

14. Method according to claim 4, wherein the result of comparing the value of the engine speed gradient with respect to time with a predetermined threshold value based on the engine speed is validated after a time delay (Tempo_cond_dem).

15. Method according to claim 11, wherein the result of comparing the value of the engine speed gradient with respect to time with a predetermined threshold value based on the engine speed is validated after a time delay (Tempo_cond_dem).

16. Method according to claim 12, wherein the result of comparing the value of the engine speed gradient with respect to time with a predetermined threshold value based on the engine speed is validated after a time delay (Tempo_cond_dem).

17. Method according to claim 2, wherein the engine speed gradient with respect to time (dN/dt) is determined from the current engine speed and the engine speed at time step (n−

1), initialized at zero.

18. Method according to claim 3, wherein the engine speed gradient with respect to time (dN/dt) is determined from the current engine speed and the engine speed at time step (n−

1), initialized at zero.

19. Method according to claim 4, wherein the engine speed gradient with respect to time (dN/dt) is determined from the current engine speed and the engine speed at time step (n−

1), initialized at zero.

20. Method according to claim 11, wherein the engine speed gradient with respect to time (dN/dt) is determined from the current engine speed and the engine speed at time step (n−

1), initialized at zero.

8. Start-off control system for a motor vehicle using dialogue between the engine control computer and the electronically controlled mechanical gearbox when restarting the vehicle in stop-and-start mode, wherein said system additionally comprises:

means for verifying whether the accelerator pedal position (Alpha pedal) with respect to a predetermined “

threshold”

position (Seuil S_Alpha) is confirmed (C2);

means for verifying whether a so-called “

autonomous condition”

value, calculated from the engine speed (N) and the engine speed gradient with respect to time (dN/dt) and compared to a predetermined engine speed gradient threshold value (Grad_N_dem), is confirmed (C1);

means for verifying whether the engine is in sequential injection mode (C3);

said verifications (C1, C2, C3) being carried out by the engine control computer;

means for transmitting a start-off control signal or “

start-off authorization”

from said engine control computer to said electronically controlled mechanical gearbox if said verifications are confirmed (C1, C2, C3).

9. System according to claim 8, wherein said “

start-off authorization”

is a signal sent by the vehicle engine control computer to the electronically controlled mechanical gearbox in the form of a flag.