Steuergerät für Automatikgetriebe

摘要

It is an object of the present invention to provide an automatic transmission with a simple and compact control apparatus for controlling clutch-to-clutch transmission-ratio shift involving a fourth brake (band brake). During the clutch-to-clutch shift, the fourth brake (band brake) is used in a self-loosening direction in which an engaging force thereof is not sensitive to variations in hydraulic pressure and a second regulated hydraulic pressure generated by a second pressure regulating valve (B-4 control valve) in accordance with a control hydraulic pressure generated by a second (throttle-pressure-control) linear solenoid valve in a margin control region thereof is supplied to a hydraulic servo of the fourth brake (band brake). In this clutch-to-clutch shift, a first regulated hydraulic pressure generated by a first pressure regulating valve (a shift-pressure control valve) in accordance with a control hydraulic pressure generated by a first (pressure-regulation) linear solenoid valve is supplied to a hydraulic servo of a third (UD direct) clutch. In addition, as a stand-alone element, the fourth brake (band brake) is also used in a self-tightening direction in which the engaging force is sensitive to variations in hydraulic pressure. At that time, the first regulated hydraulic pressure generated by the first pressure regulating valve (the shift-pressure control valve) is supplied to the hydraulic servo of the fourth brake (band brake).