Method and device for controlling hydraulic pressure for automatic transmission for vehicle


PURPOSE: To prevent a shock on changing gears and a striking sound by varying the overlapping of the pressure-lowering curve of a hydraulic pressure with the pressure-rising curve of said hydraulic pressure, being related to the output condition of an engine. CONSTITUTION: When the output torque of an engine is negative and as a solenoid value 314 is unexcited in relation to the operating parameter of a vehicle, the spool 350 of a selector valve 348 is moved against the energizing force of a spring 352, causing the port 288 of a shift valve 274 to be connected to a rapid discharge oil passage 346. And, a working fluid in the hydraulic operating part 322 of a brake for a low-speed gear stage is discharged not only through a discharge oil passage 286 but also through the rapid discharge oil passage 346. Thereby, the overlapping of a pressure-lowering curve in the hydraulic operating part 322 with a pressure-rising curve in a clutch 72 for a high-speed gear stage can be reduce, nearly eliminating an area in which the output torque of a subsidiary transmission becomes negative, reducing its width of variation. COPYRIGHT: (C)1987,JPO&Japio




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    US-4955852-ASeptember 11, 1990Toyota Jidosha Kabushiki KaishaPlanetary gear mechanism having means for accurate alignment of sun gear