Patent ID: 6139469
Filing Date: 2000-10-31
Classification: F16H,Y10T

Abstract:
A hydraulic control system used in automatic transmissions comprising:a pressure regulator for controlling hydraulic pressure generated by an oil pump, the pressure regulator comprising a pressure regulator valve;a pressure reducer for maintaining pressure at a level lower than line pressure, the presure reducer comprising a reducing valve;a damper clutch controller for operating a damper clutch of a torque converter;a shift controller for forming shift modes, the shift controller comprising a manual valve indexed with a select lever operated by a user;a hydraulic pressure controller for providing shift quality and shift responsiveness to enable smooth shifting; anda hydraulic pressure distributor for supplying suitable hydraulic pressures to first, second, third, fourth and fifth friction elements operating as input and reaction elements in each shift stage, the hydraulic pressure distributor comprising a plurality of spool valves,wherein the hydraulic pressure controller comprises a first pressure control valve for controlling the hydraulic pressure supplied to the first friction element, a second pressure control valve for controlling the hydraulic pressure supplied to the second friction element, a third pressure control valve for controlling the hydraulic pressure supplied to the third friction element, and an N-R control valve which controls reverse pressure supplied to the fourth friction element;the hydraulic pressure distributor comprises: (a) a switch valve supplying a part of operational pressure of a third operational element to the pressure regulator valve for line pressure control, the third operational element operating in a third and fourth speed of a drive D range while being controlled by forward pressure supplied from the manual valve; (b) a first fail-safe valve controlled by part of the hydraulic pressure supplied to the first, third and fifth friction elements and control pressure supplied from the manual valve in the drive D range, and which supplies hydraulic pressure the second friction elements in a second and fourth speed of the drive D range or exhausts the hydraulic pressure supplied to the second friction element when a transmission control unit is malfunctioning; and (c) a second fail-safe valve controlled by control pressure supplied from the second pressure control valve and hydraulic pressure supplied from the manual valve via a low control valve in a low L range, and which supplies hydraulic pressure supplied to the third pressure control valve means to the third friction element in the third and fourth speeds of the drive D range and to the fourth friction element in the low L range, and supplies reverse pressure supplied through a reverse pressure line to the fourth friction element in a reverse R range; wherein the low control valve controls by the hydraulic pressure supplied to the third friction element, and controls the hydraulic pressure supplied to the second fail-safe valve from the manual valve in the low L range.