Continuously variable transmission for motor vehicle, has ratio control subsystem that limits speed ratio of variator by commanding speed ratio that is higher than actual speed ratio in overdrive direction

摘要

The transmission has a ratio control subsystem connected to a variator (12) i.e. toroidal race rolling type variator. The ratio control subsystem (14) limits speed ratio of the variator by commanding a speed ratio that is higher than actual speed ratio in an overdrive direction. The ratio control subsystem includes a piston (38) connected to a shaft and arranged in a chamber (40) of a housing (52). The piston divides the chamber into two subchambers (40A, 40B) that communicate with a sleeve (50) coupled to a motor (54). The piston is coupled to a spool (46) arranged in the sleeve.