Speed ratio controller and control method of continuously variable transmission

A speed ratio controller of a continuously variable transmission for a vehicle, said continuously variable transmission continuously changing a speed ratio by displacement of a speed change medium in response to an actuator, said controller comprising:

• sensors for detecting a real speed ratio, and
• a microprocessor programmed to:
• calculate a target speed ratio i* of said transmission,
• calculate a control amount v of said actuator so that said real speed ratio i coincides with the target speed ratio i*,
• calculate a command value u by correcting said control amount v based on a non-linear relation between said displacement and said real speed ratio, and
• control said actuator based on the command value u,
• wherein said speed change medium comprises a power roller which varies said real speed ratio i according to a variation of a gyration angle .phi. of said power roller, said displacement is represented by said gyration angle .phi., said transmission comprises a control valve which varies said gyration angle .phi. hydraulically and a mechanical feedback mechanism which mechanically feeds back a variation of said gyration angle .phi. to said control valve, and said microprocessor is programmed to calculate a mechanical feedback amount due to said mechanical feedback mechanism based on said real speed ratio i, calculate a corrected control amount v' by adding said mechanical feedback amount to said control amount v, and calculate said command value u by applying an inverse function h.sup.-1 (i) of a first function h(.phi.) representing said real speed ratio i by said gyration angle .phi., to said corrected control amount v'.

A speed ratio controller of a continuously variable transmission for a vehicle, said continuously variable transmission continuously changing a speed ratio by displacement of a speed change medium in response to an actuator, said controller comprising:

• sensors for detecting a real speed ratio, and
• a microprocessor programmed to:
• calculate a target speed ratio i* of said transmission,
• calculate a control amount v of said actuator so that said real speed ratio i coincides with the target speed ratio i*,
• calculate a command value u by correcting said control amount v based on a non-linear relation between said displacement and said real speed ratio, and
• control said actuator based on the command value u,
• wherein said speed change medium comprises a pulley comprising a movable conical plate, said movable conical plate varying said real speed ratio i according to a variation of a conical plate displacement, and said microprocessor is programmed to calculate said command value u by correcting said control amount v based on a non-linear relation between said conical plate displacement and said real speed ratio,
• wherein said microprocessor is programmed to calculate said command value u by correcting said control amount v based on an inverse function h.sup.-1 of a function h, said function h representing said conical plate displacement by said real speed ratio i.

A speed ratio controller of a continuously variable transmission for a vehicle, said continuously variable transmission continuously changing a speed ratio by displacement of a speed change medium in response to an actuator, said controller comprising:

• sensors for detecting a real speed ratio, and
• a microprocessor programmed to:
• calculate a target speed ratio i* of said transmission,
• calculate a control amount v of said actuator so that said real speed ratio i coincides with the target speed ratio i*,
• calculate a command value u by correcting said control amount v based on a non-linear relation between said displacement and said real speed ratio, and
• control said actuator based on the command value u,
• wherein said microprocessor is programmed to calculate a feed forward control amount of said actuator based on said target speed ratio i*, and selectively apply said command value u or said feed forward control amount to control said actuator,
• wherein said speed change medium comprises a power roller which varies said real speed ratio i according to a variation of the gyration angle .phi. of said power roller, said displacement is represented by said gyration angle .phi., and said microprocessor is programmed to calculate said feed forward control amount based on an inverse function h.sup.-1 (i) of a first function h(.phi.), said first function h(.phi.) representing said real speed ratio i by said gyration angle .phi..

A speed ratio controller of a continuously variable transmission for a vehicle, said continuously variable transmission continuously changing a speed ratio by displacement of a speed change medium in response to an actuator, said controller comprising:

• sensors for detecting a real speed ratio, and
• a microprocessor programmed to:
• calculate a target speed ratio i* of said transmission,
• calculate a control amount v of said actuator so that said real speed ratio i coincides with the target speed ratio i*,
• calculate a command value u by correcting said control amount v based on a non-linear relation between said displacement and said real speed ratio, and
• control said actuator based on the command value u,
• wherein said microprocessor is programmed to calculate a feed forward control amount of said actuator based on said target speed ratio i*, and selectively apply said command value u or said feed forward control amount to control said actuator,
• wherein said microprocessor is programmed to calculate said control amount v based on a difference between said real speed ratio i and said target speed ratio i*, calculate a corrected control amount v' by correcting said control amount v based on a non-linear relation between said displacement and said real speed ratio, obtain said command value u by processing said corrected control amount v' by a low pass filter provided with a predetermined time constant .kappa., and increase said predetermined time constant .kappa. for a predetermined time when a change-over is made between application of said feed forward control amount and application of said command value u during control of said actuator.

A speed ratio controller of a continuously variable transmission for a vehicle, said continuously variable transmission continuously changing a speed ratio by displacement of a speed change medium in response to an actuator, said controller comprising:

• sensors for detecting a real speed ratio, and
• a microprocessor programmed to:
• calculate a target speed ratio i* of said transmission,
• calculate a control amount v of said actuator so that said real speed ratio i coincides with the target speed ratio i*,
• calculate a command value u by correcting said control amount v based on a non-linear relation between said displacement and said real speed ratio, and
• control said actuator based on the command value u,
• wherein said microprocessor is programmed to calculate a feed forward control amount of said actuator based on said target speed ratio i*, and selectively apply said command value u or said feed forward control amount to control said actuator,
• wherein said speed change medium comprises a power roller which varies said real speed ratio i according to a variation of a gyration angle .phi. of said power roller, said displacement is represented by said gyration angle .phi., said transmission comprises a control valve which varies said gyration angle .phi. hydraulically and a mechanical feedback mechanism which mechanically feeds back a variation of said gyration angle .phi. to said control valve, and said microprocessor is programmed to calculate a mechanical feedback amount b due to said mechanical feedback mechanism based on said real speed ratio i, calculate said control amount v by applying proportional integral control using a proportional gain c.sub.1 and integral gain c.sub.0 to a difference between said real speed ratio i and said target speed ratio i*, calculate a corrected control amount v' by adding said mechanical feedback amount b to said control amount v, and calculate said command value u by correcting said corrected control amount v' based on a non-linear relation between said displacement and said real speed ratio.