Brake servo unit control device, -method and -vehicle

The invention relates to a brake servo unit (101), a method of operating said unit and a vehicle mounted with said unit, wherein said unit having a boost function including a master cylinder (102), a pressure sensor (103) for detecting the pressure of the master cylinder (102), a current source (104) for supplying the solenoid current to the servo unit (101), a pressure-increase control function (107) for controlling the liquid pressure-increasing of the master cylinder (102) and a learning function (113) for learning and recording a pressure-increase starting current command. The solenoid current increases at low temperatures and decreases at high temperatures because the modulus of elasticity of an elastically deformable valve body and the slide resistance of an elastically deformable seal member vary with temperatures. Therefore the solenoid current for opening the valve mechanism from a closed position is required to be changed with low and high temperatures.