Patent ID: 6030317
Filing Date: 2000-02-29
Classification: F16H,Y10T

Abstract:
A hydraulic control in an automatic transmission having at least first and second switching components (1, 2) with which is effected a gearshift from a neutral position (N) to a forward drive position (D), reverse drive position (R), parking position (P) or other switching positions for forward and reverse drive and having a hydraulic system with pressure lines and with the following features:a) said switching components (1, 2) are actuatable with pressure which is fed via pressure lines (24, 25) connected with a selector slide (15);b) said switching device (26) has a switching valves (27, 28) contained in valve housings (31, 31'), for each switching component (1, 2), said valve housings (31, 31') of said switching valves (27, 28) being supplied with pressurized medium via a respective pressure line (24, 25) and having a tank connection (37, 37') wherein:c) each of said switching valves (27, 28) is coordinated with a damper-switching and vent valve (29, 30);d) each of said switching valves (27, 28) has in the respective valve housing (31, 31'), a movable valve piston (33, 33') and a damper piston (40, 40') and a spring (38, 38') wherein said damper piston can be loaded with a control pressure which is supplied by the respective damper, switching and vent valve (29, 30) connectable with the particular switching valve (27, 28);e) said switching device (26) has a safety and vent device designed so that upon actuation of one of said switching components (1, 2) the other switching component is automatically disengaged; andwherein a control pressure which engages an active surface of said valve piston (33, 33') of the switching valve (28 or 27) belonging to the switching component (2 or 1) not selected, is supplied, via a control pressure line (44 or 45) in a manner such that respective tank connection (37, 37') is opened, said control pressure also discharges in the damper, switching and vent valve (29, 30) belonging to the selected switching component (1 or 2) in such a manner that said respective damper piston (40, 40') thereby loaded with pressure produces by continuous prestress of the respective spring (38, 38'), a pressure ramp needed for switching the corresponding switching component.