Patent ID: 7001299

Claim:
An automatic transmission including plural friction engaging elements configures plural shift ranges based on combinations of each friction engaging element being in engaging or disengaging condition and a controlling unit for controlling the friction engaging elements to be in engaging or disengaging condition by controlling a hydraulic pressure applied thereto, comprising: a switching means for switching the condition of the controlling unit to a learning mode for learning a pre-charge time at a predetermined pre-charge pressure; a means for determining the pre-charge time activated upon the leaning mode based on input values indicating at least a turbine rotation number, wherein the means for determining the pre-charge time on condition that a vehicle is not traveling and the controlling unit is switched to the learning mode, includes: a means for moving the friction engaging element toward engaging side by controlling the hydraulic pressure applied to the friction engaging element to be at the predetermined pre-charge pressure by the controlling portion while an input shaft rotating number of the automatic transmission is constant; a means for measuring and memorizing the input values with predetermined intervals in a predetermined determining cycle; a means for learning and setting a current time as the pre-charge time when a change of the input value due to a decline of the turbine rotation number within the determining cycle fulfills a predetermined noise eliminating condition and a differential between a current input value and a former input value and a differential between the former input value and an input value preceding the former input value exceed a predetermined threshold.