Patent ID: 6626793
Filing Date: 2003-09-30
Classification: F16H

Abstract:
An hydraulic control circuit for a CVT transmission having a variator and a plurality of regime change clutches comprising:first and second hydraulic supply pipes; first and second hydraulic pumps associated with said first and second supply pipes, respectively, for pumping hydraulic fluid therethrough and for raising its pressure; a first hydraulic pressure control valve for controlling the pressure of hydraulic fluid to be supplied to roller control pistons of the variator; a second hydraulic pressure control valve for controlling the pressure of hydraulic fluid to be supplied to said regime change clutches of the transmission, wherein said first and second hydraulic pressure valves are connected in flow series; and at least one fluid directing valve for selectively directing flow from each of said first and second hydraulic pumps, respectively, to a first point upstream of said first valve and to a second point downstream of said first valve but upstream of said second valve.