Hydraulische Steuerung für ein automatisches Fahrzeuggetriebe mit einer Kupplung mit zwei Schaltzuständen und zwei parallelen Druckversorgungsleitungen dafür.

摘要

For an automatic transmission for a vehicle including a speed stage shifting device such as shown in Fig. 1 in which the clutch C1 is adapted to be engaged when the 2nd speed stage and the 3rd speed stage are set up and disengaged when the 4th speed stage is set up, the engagement of the clutch C1 being essential for setting up the 2nd speed stage while the engagement of the clutch C1 is not essential for setting up said second speed stage unless engine brake availability is required, a hydraulic control device includes a first passage 235 and a second passage 329 for supplying a hydraulic pressure to the clutch C1 in parallel with one another, the first passage having a substantially less fluid flow resistance than the second passage, and a fluid flow switching over means including a 1-2 shift valve 210 and a C1 control valve 300 for alternatively communicating the first or the second passage while interrupting the second or the first passage according to whether the 2nd speed stage or the 3rd speed stage is set up. An accumulator 450 may be provided in the second passage 329. Further, a one way valve 469, or more desirably a parallel connection of the one way valve 469 and an orifice 467 may be provided between the accumulator and the clutch C1.