Automatic transmission control system

摘要

An automatic transmission comprises a plurality of clutches 11 SIMILAR 15, which are provided to select power transmission paths, respectively, in a parallel shaft speed change mechanism TM and a plurality of shift valves 60 SIMILAR 68, which are used for controlling the supply and drain of hydraulic oil to and from these clutches. For this automatic transmission, a control system comprises a plurality of solenoid valves 81 SIMILAR 85, which are used for controlling the supply and drain of a line pressure so as to control the actuation of these shift valves. This system, when the shift lever is manipulated to set the neutral range, sets the transmission into either a first neutral mode or a second neutral mode depending upon the speed of the vehicle, the first neutral mode being set when the vehicle is driving at a speed equal to or more than a critical speed, and the second neutral mode being set when the vehicle speed is less than the critical speed. In this control, the combination of on/off operations of the solenoid valves for setting the first neutral mode is different from the combination for setting the second neutral mode.