Extension of operating range of feedback in CVT ratio control

A method of extending operating range of feedback in ratio control in a continuously variable transmission (CVT) for a motor vehicle, comprising:

• providing a first pulse train signal by an input speed sensor of an input speed sensor system including one rotating wheel with a rotating input member of the CVT;
• providing a second pulse train signal by an output speed sensor of an output speed sensor system including another rotating wheel with a rotating output member of the CVT;
• repeating updating of an old value of rotational speed of the input member to a new value thereof, which results from computation using the pulses of the first pulse train signal, at intervals governed by the first pulse train;
• repeating updating of an old value of rotational speed of the output member to a new value thereof, which results from computation using the pulses of the second pulse train, at intervals governed by the second pulse train;
• repeating updating of an old value of a ratio between the latest value of the rotational speed of the input member and the latest value of the rotational speed of the output member to a new value thereof each time immediately after the values of the rotational speeds of the input and output members have been updated since the latest updating of an old value of the ratio;
• and
• using the new values of the ratio as an actual value of ratio between rotational speed of the input member of the CVT and rotational speed of the output member of the CVT in conducting a feedback in ratio control in the CVT during a predetermined operational range of the CVT.

A system for extending operating range of feedback in ratio control in a continuously variable transmission (CVT) for a motor vehicle, the CVT including a rotating input member and a rotating output member, the system comprising:

• an input speed sensor system including one rotating wheel with the rotating input member of the CVT and an input speed sensor providing a first pulse train signal;
• an output speed sensor system including another rotating wheel with the rotating output member of the CVT and an output speed sensor providing a second pulse train signal;
• an actual ratio-computing (ARC) component,
• the ARC component including a rotational speed computing section, a synchronous & smoothing filter and CVT ratio computing section,
• the rotational speed computing section being operable to repeat updating of an old value of rotational speed of the input member to a new value thereof, which results from computation using the pulses of the first pulse train signal, at intervals governed by the first pulse train,
• the rotational speed computing section being operable to repeat updating of an old value of rotational speed of the output member to a new value thereof, which results from computation using the pulses of the second pulse train, at intervals governed by the second pulse train,
• the synchronous & smoothing filter and CVT ratio computing section being operable to repeat updating of an old value of a ratio between the latest value of the rotational speed of the input member and the latest value of the rotational speed of the output member to a new value thereof each time immediately after the values of the rotational speeds of the input and output members have been updated since the latest updating of an old value of the ratio,
• the ARC component being operable to use the new values of the ratio as an actual value of ratio between rotational speed of the input member of the CVT and rotational speed of the output member of the CVT;
• a desired ratio-computing (DRC) component operable to provide a desired value of ratio between rotational speed of the input member of the CVT and rotational speed of the output member of the CVT;
• and
• a controller conducting feedback control in ratio control of the CVT based on the actual value of ratio between rotational speed of the input member of the CVT and rotational speed of the output member of the CVT and the desired value thereof during a predetermined operational range of the CVT.

A system for deriving an actual value of a ratio between rotational speed of an input member of a continuously variable transmission (CVT) and rotational speed of an output member of the CVT from a first pulse train signal and a second pulse train signal, the first pulse train signal being provided by an input speed sensor of an input speed sensor system including one rotating wheel with the input member, the second pulse train signal being provided by an output speed sensor of an output speed sensor system including another rotating wheel with the output member, the system comprising:

• means for repeating updating of an old value of rotational speed of the input member to a new value thereof, which results from computation using the pulses of the first pulse train signal, at intervals governed by the first pulse train;
• means for repeating updating of an old value of rotational speed of the output member to a new value thereof, which results from computation using the pulses of the second pulse train, at intervals governed by the second pulse train;
• and
• means for repeating updating of an old value of a ratio between the latest value of the rotational speed of the input member and the latest value of the rotational speed of the output member to a new value thereof each time immediately after the values of the rotational speeds of the input and output members have been updated since the latest updating of an old value of the ratio.