Patent ID: 6527668
Filing Date: 2003-03-04
Classification: F16H,Y10T

Abstract:
A hydraulic system for a stepless automatic transmission of a vehicle driven by a motor, the hydraulic system having a variator with a drive side first conical disk pair and a power takeoff second conical disk pair and an endless belt drivingly engaging the first and second conical disk pairs, the first conical disk pair having a sliding primary conical disk which is moveable in an axial direction and the second conical disk pair having a sliding secondary conical disk which is moveable in an axial direction and positions of the primary and secondary conical disks being regulated by a hydraulic control apparatus, the hydraulic control apparatus having electromagnetic positioning members and hydraulic valves which are regulated by an electronic control apparatus, the hydraulic system includes a lubrication/cooling circuit with a cooler (11) located therein, and a line (14) leading from the cooler (11) to an oil sump (1);wherein an orifice (13) is inserted in the line (14) leading from the cooler (11) to the oil sump (1), and a cross-sectional flow opening of the orifice (13) is controllable between a first position, in which an opening of the orifice (13) is nearly closed, and a second position, in which the opening of the orifice (13) is substantially completely open, as a function of one of a rotational speed of the motor and a driving speed of the vehicle.