Hydraulic control device and hydraulic control method for vehicle automatic transmission

A hydraulic control device for a vehicle automatic transmission in which a plurality of hydraulic friction engagement devices are selectively engaged to establish a plurality of speeds having different speed ratios, comprising:

• a hydraulic control unit that uses an electromagnetic valve device to control engagement hydraulic pressures supplied to the respective hydraulic friction engagement devices by setting a driving current corresponding to the engagement hydraulic pressures;
• and
• an estimated torque calculation unit that calculates an input torque related value of the vehicle automatic transmission, wherein
• during a non-shift operation in which a predetermined speed of the vehicle automatic transmission is kept, the hydraulic control unit sets the engagement hydraulic pressure applied to the hydraulic friction engagement device associated with formation of the predetermined speed to a hydraulic pressure based on the input torque related value to thereby place the electromagnetic valve device in a regulated state, while
• during a shift operation of the vehicle automatic transmission, prior to a start of releasing control of a release-side hydraulic friction engagement device of the hydraulic friction engagement devices, the hydraulic control unit sets the driving current to temporarily increase, by a predetermined hydraulic pressure with respect to the engagement hydraulic pressure during the non-shift operation, the engagement hydraulic pressure applied to the release-side hydraulic friction engagement device for a predetermined period of time, and
• the release-side hydraulic friction engagement device is an engaged hydraulic friction engagement device of the hydraulic friction engagement device.