UNITA' DI COMANDO PER UNA TRASMISSIONE, IN PARTICOLARE PER AUTOVEICOLI

摘要

A power train for use in a motor vehicle has an infinitely variable transmission with two sheaves and a belt which is trained over the sheaves. The sheaves have fixed and axially movable flanges, and one of the sheaves is driven by the engine through a torque sensor. A first hydraulic circuit has a first pump which can supply pressurized oil to the hydraulic motors for the axially movable sheaves at a pressure determined by the torque sensor. A second hydraulic circuit has a second pump serving to supply pressurized oil to a further motor which varies the ratio of the transmission and to two friction clutches between the second sheave and an output member. The pressure of oil in the second circuit is determined by a pressure regulating valve which is adjustable by a control unit in dependency on one or more parameters of the engine. A first distributing valve can connect the second pump with the further motor and/or with one of the two clutches, and a second distributing valve can connect the first distributing valve with the one or the other clutch. One of the clutches can drive the output member in a first direction, and the other clutch can drive the output member by way of a planetary in a second direction counter to the first direction.