Method for operating a motor vehicle having a continuously variable transmission by continuously changing the transmission ratio or detecting if a braking operation is present and continuously adjusting the transmission

A method of operating a motor vehicle such as a passenger car, the motor vehicle being equipped with a motor and an electronically controlled, continuously variable transmission, the method comprising the steps of:

• detecting a driving state defined by downhill travel;
• detecting the speed of the vehicle at the start of the downhill travel and storing the vehicle speed;
• continuously changing the transmission in such a manner that said vehicle speed is substantially maintained while utilizing the braking action of the motor thereby defining a downhill travel motor braking mode of operation;
• making a controlled adjustment of the gear ratio in the downhill travel motor braking mode of operation;
• detecting the instantaneous motor rpm (NE.sub.act) or the transmission input rpm;
• comparing the instantaneous motor rpm (NE.sub.act) or the transmission input rpm as a control variable to a corresponding guide variable (NE.sub.des);
• and,
• in dependence upon this comparison result, changing the gear ratio (i) of the transmission in the sense of an approximation to the guide variable.

A method of operating a motor vehicle such as a passenger car, the motor vehicle being equipped with a motor and an electronically controlled, continuously variable transmission, the method comprising the steps of:

• detecting a driving state defined by downhill travel;
• detecting the speed of the vehicle at the start of the downhill travel and storing the vehicle speed;
• continuously changing the transmission in such a manner that said vehicle speed is substantially maintained while utilizing the braking action of the motor thereby defining a downhill travel motor braking mode of operation;
• using a controller having a proportional component and a differential component for controlling said transmission;
• and,
• making a controlled adjustment of the gear ratio in the downhill travel motor braking mode of operation.

A method of operating a motor vehicle such as a passenger car, the motor vehicle being equipped with a motor and an electronically controlled, continuously variable transmission, the method comprising the steps of:

• detecting a driving state defined by downhill travel;
• detecting the speed of the vehicle at the start of the downhill travel and storing the vehicle speed;
• continuously changing the transmission in such a manner that said vehicle speed is substantially maintained while utilizing the braking action of the motor thereby defining a downhill travel motor braking mode of operation;
• detecting the instantaneous vehicle speed V.sub.act ;
• low-pass filtering said instantaneous vehicle speed V.sub.act and applying the low-pass filtered instantaneous vehicle speed V.sub.actF as an actual variable to a controller for said transmission;
• and,
• making a controlled adjustment of the gear ratio in the downhill travel motor braking mode of operation.

A method of operating a motor vehicle such as a passenger car, the motor vehicle being equipped with a motor and an electronically controlled, continuously variable transmission, the method comprising the steps of:

• detecting a driving state defined by downhill travel;
• detecting the speed of the vehicle at the start of the downhill travel and storing the vehicle speed;
• continuously changing the transmission in such a manner that said vehicle speed is substantially maintained while utilizing the braking action of the motor thereby defining a downhill travel motor braking mode of operation;
• storing the detected motor vehicle speed as a desired speed V.sub.des at the start of downhill travel;
• detecting the instantaneous motor vehicle speed V.sub.act during said downhill travel;
• comparing said desired speed V.sub.des to the instantaneous motor vehicle speed V.sub.act during downhill travel;
• forming a new desired speed in the case where the deviation between the desired speed V.sub.des and the instantaneous vehicle speed V.sub.act exceeds a pregiven threshold T;
• low-pass filtering the instantaneous vehicle speed V.sub.act to obtain a low-pass filtered instantaneous V.sub.actF ;
• and,
• making the comparison by applying the low-pass filtered instantaneous vehicle speed V.sub.actF.

A method of operating a motor vehicle such as a passenger car, the motor vehicle being equipped with a motor and an electronically controlled, continuously variable transmission, the method comprising the steps of:

• detecting a driving state defined by downhill travel;
• detecting the speed of the vehicle at the start of the downhill travel and storing the vehicle speed;
• continuously changing the transmission in such a manner that said vehicle speed is substantially maintained while utilizing the braking action of the motor thereby defining a downhill travel motor braking mode of operation;
• making a controlled adjustment of the gear ratio in the downhill travel motor braking mode of operation;
• storing the detected motor vehicle speed as a desired speed V.sub.des at the start of downhill travel;
• detecting the instantaneous motor vehicle speed V.sub.act during said downhill travel;
• comparing said desired speed V.sub.des to the instantaneous motor vehicle speed V.sub.act during downhill travel;
• forming a new desired speed in the case where the deviation between the desired speed V.sub.des and the instantaneous vehicle speed V.sub.act exceeds a pregiven threshold T;
• and,
• increasing the instantaneous vehicle speed V.sub.act by the threshold T to form the new desired speed.

A method of operating a motor vehicle such as a passenger car, the motor vehicle being equipped with a motor and an electronically controlled, continuously variable transmission, the method comprising the steps of:

• detecting a driving state defined by downhill travel;
• detecting the speed of the vehicle at the start of the downhill travel and storing the vehicle speed;
• continuously changing the transmission in such a manner that said vehicle speed is substantially maintained while utilizing the braking action of the motor thereby defining a downhill travel motor braking mode of operation;
• storing the detected vehicle speed as desired speed V.sub.des at the start of the downhill travel;
• detecting the instantaneous vehicle speed V.sub.act and, by means of a controlled change of the gear ratio, causing the instantaneous vehicle speed V.sub.act to approximate the desired speed V.sub.des ;
• with a desired overrun force F.sub.des being determined from the deviation between the desired speed V.sub.des and the instantaneous speed V.sub.act ;
• and, with a desired motor rpm NE.sub.des being determined in dependence upon this desired overrun force F.sub.des ;
• making a controlled adjustment of the gear ratio in the downhill travel motor braking mode of operation.