Method for controlling a rolling or coasting function of a vehicle

A method of controlling either a rolling or a coasting function of a vehicle for a drive train comprising a drive motor, either an automatic or an automated transmission, that is controllable by transmission controls with controllable shifting for interrupting a flow of power in the drive train, a brake device, a drive speed control device, a current roadway incline(α_Fb), vehicle speed (v_F) and vehicle acceleration (a_F) are determined, and the vehicle speed (v_F) being regulated by the speed control device, and the brake device being controllable for actuation when driving on a downhill gradient section (2), the method comprising the steps of:

• checking either rolling or a coasting condition for a downhill gradient taper (3) when driving on the downhill gradient section (2);
• interrupting the flow of power in the drive train, with the transmission controls, before entering a flat area (4) at least one of when the rolling or the coasting condition is satisfied and before an engine torque is requested from the driving speed control device;
• and
• interrupting the flow of power close to the deactivation of the braking device once either the rolling or the coasting condition is fulfilled.

A method of controlling either a rolling or a coasting function of a commercial vehicle (1) having a drive train comprising a drive motor, either an automatic or an automated transmission, which is controllable by transmission controls with controllable shifting devices for interrupting a flow of power in the drive train, an auxiliary braking system, and a drive speed control device, the method comprising the steps of:

• determining current roadway incline (α_Fb), a vehicle speed (v_F) and a vehicle acceleration (a_F);
• regulating the vehicle speed (v_F) with the drive speed control device;
• controlling the auxiliary braking system to actuate the auxiliary braking system when driving on a downhill gradient section (2);
• checking either a rolling or a coasting condition for a downhill gradient taper (3) when driving on the downhill gradient section (2);
• interrupting the flow of power in the drive train, via the transmission controls, when either the rolling or the coasting function is satisfied and before at least one of entering a flat area (4) and receiving an engine torque request from the driving speed control device;
• and
• considering either the rolling or the coasting condition satisfied when the driving speed control device is active and at least one of:
• a) the braking device is deactivated,
• b) a set difference (Δv_B_T), between a upper speed regulated by a Bremsomat (v_B) and a lower speed regulated by a Tempomat (v_T), is greater than a threshhold,
• c) the current vehicle speed (v_F) is close to a set Bremsomat speed (v_B) and is higher than a threshold of a set Tempomat speed (v_T),
• d) the current vehicle acceleration (a_F), is identified as being either a deceleration toward zero, or a threshold close to zero (a_F_lim),
• e) the current roadway incline (α_Fb) lies above a threshold, and
• f) a time derivative (α′_Fb) of the roadway incline (α′_Fb)is either above zero or above a threshold close to zero.