Method for operating a motor vehicle
View Patent ↗In a motor vehicle having an internal combustion engine which has an automatic start/stop device, and a controllable brake device at the start of and during an automatic stop phase, the effect of a braking torque which is greater than a threshold value is ensured. For this purpose, the brake device can increase the braking torque. The threshold value is previously calculated in such a way that the motor vehicle is reliably prevented from rolling away. As a result, the internal combustion engine can be stopped frequently, and at the same time unintentional rolling away of the motor vehicle during the stop phase can be avoided.
1. A method for operating a motor vehicle having an internal combustion engine, an automatic start/stop device for the internal combustion engine, a controllable brake device by means of which a braking torque can be applied to the motor vehicle, and a brake pedal which can be activated by a vehicle driver; wherein the brake device is actuated by a control device in an automatic stop phase of the internal combustion engine as a function of a degree of activation of the brake pedal, and the control device can increase the braking torque independently of the degree of activation of the brake pedal; said method comprising:
determining a threshold value as a function of at least one of state variables and operating variables of the motor vehicle, before the brake device is actuated;
at the start of and during said automatic stop phase of the internal combustion engine, checking whether a currently acting braking torque is smaller than the threshold value; and
increasing the brake torque to a value which is greater than or equal to the threshold value when said currently acting braking torque is smaller than the threshold value.
2. The method as claimed in claim 1 , wherein the control device determines the threshold value as a function of environmental variables before the brake device is actuated.
3. The method as claimed in claim 1 , wherein the control device:
determines a specific braking torque (M Brake — stop ) which is necessary to stop the motor vehicle; and
sets the aforesaid threshold value to a value which is greater than or equal to the specific braking torque (M Brake — stop ).
4. The method as claimed in claim 2 , wherein the control device:
determines a specific braking torque (M Brake — stop ) which is necessary to stop the motor vehicle; and
sets the aforesaid threshold value to a value which is greater than or equal to the specific braking torque (M Brake — stop ).
5. The method as claimed in claim 1 , wherein the control device increases the braking torque before the internal combustion engine starts.
6. The method as claimed in claim 2 , wherein the control device increases the braking torque before the internal combustion engine starts.
7. The method as claimed in claim 3 , wherein the control device increases the braking torque before the internal combustion engine starts.
8. The method as claimed in claim 4 , wherein the control device increases the braking torque before the internal combustion engine starts.
9. A method for operating a motor vehicle having an internal combustion engine, an automatic start/stop device for the internal combustion engine, a controllable brake device by means of which a braking torque can be applied to the motor vehicle, and a brake pedal which can be activated by a vehicle driver; wherein the brake device is actuated by a control device in an automatic stop phase of the internal combustion engine as a function of a degree of activation of the brake pedal, and the control device can increase the braking torque independently of the degree of activation of the brake pedal; said method comprising:
the control device determining a threshold value as a function of at least one of state variables and operating variables of the motor vehicle, before the brake device is actuated;
at the start of and during an automatic stop phase of the internal combustion engine, the control device checking whether a currently acting braking torque is smaller than the threshold value; and
when there is a positive result of the check, the control device increasing the brake torque to a value which is greater than or equal to the threshold value;
wherein:
during the stop phase the control device monitors whether the motor vehicle is moving; and
in case of a movement, the control device actuates the brake device in such a way that the braking torque is increased.
10. A method for operating a motor vehicle having an internal combustion engine, an automatic start/stop device for the internal combustion engine, a controllable brake device by means of which a braking torque can be applied to the motor vehicle, and a brake pedal which can be activated by a vehicle driver; wherein the brake device is actuated by a control device in an automatic stop chase of the internal combustion engine as a function of a degree of activation of the brake pedal, and the control device can increase the braking torque independently of the degree of activation of the brake pedal; said method comprising:
the control device determining a threshold value as a function of at least one of state variables and operating variables of the motor vehicle, before the brake device is actuated;
at the start of and during an automatic stop phase of the internal combustion engine, the control device checking whether a currently acting braking torque is smaller than the threshold value;
when there is a positive result of the check, the control device increasing the brake torque to a value which is greater than or equal to the threshold value;
wherein:
the control device determines the threshold value as a function of environmental variables before the brake device is actuated;
during the stop phase the control device monitors whether the motor vehicle is moving; and
in case of a movement, the control device actuates the brake device in such a way that the braking torque is increased.
11. A method for operating a motor vehicle having an internal combustion engine, an automatic start/stop device for the internal combustion engine, a controllable brake device by means of which a braking torque can be applied to the motor vehicle, and a brake pedal which can be activated by a vehicle driver; wherein the brake device is actuated by a control device in an automatic stop phase of the internal combustion engine as a function of a degree of activation of the brake pedal, and the control device can increase the braking torque independently of the degree of activation of the brake pedal; said method comprising:
the control device determining a threshold value as a function of at least one of state variables and operating variables of the motor vehicle, before the brake device is actuated;
at the start of and during an automatic stop phase of the internal combustion engine, the control device checking whether a currently acting braking torque is smaller than the threshold value; and
when there is a positive result of the check, the control device increasing the brake torque to a value which is greater than or equal to the threshold value;
wherein:
the control device codetermines a specific braking torque (M Brake — stop ) which is necessary to stop the motor vehicle;
the control device sets the aforesaid threshold value to a value which is greater than or equal to the specific braking torque (M Brake — stop );
during the stop phase the control device monitors whether the motor vehicle is moving; and
in case of a movement, the control device actuates the brake device in such a way that the braking torque is increased.