An hydraulic control circuit for a continuously-variable-transmission

摘要

The present invention provides an hydraulic control circuit for a continuously-variable-ratio transmission An hydraulic control circuit for a CVT transmission includes a first hydraulic pressure control valve V1 for controlling the pressure of hydraulic fluid to be supplied to the roller control pistons of the variator and a second hydraulic pressure control valve V2 for controlling the pressure of hydraulic fluid to be supplied to a clutching arrangement of the transmission. Said valves V1, V2 are connected in flow series and by a first fluid directing valve means V3(S1, S2) for directing flow from each pump PL, PR to a first point P upstream of valve V1 or to a second point P downstream of valve V1 but upstream of valve V2. By adopting such an arrangement it is possible to control the clutches without affecting the roller position and vice versa.