Patent ID: 6755761
Filing Date: 2004-06-29
Classification: F15C,F16H,F16K,Y10T

Abstract:
An electronically controlled automatic transmission, comprising:an input shaft; an output shaft; a plurality of gears providing driving connection between said input shaft and said output shaft; one of a hydraulically operated brake band and a hydraulically operated clutch which is operable to effect a change in the gear reduction provided by said gears between said input shaft and said output shaft; a source of pressurized hydraulic fluid; and a microvalve device selectively operable to control passage of pressurized hydraulic fluid from said source to said one of a hydraulically operated brake band and a hydraulically operated clutch to operate said one of a hydraulically operated brake band and a hydraulically operated clutch wherein said microvalve device includes a microvalve movable between a pressure increase position wherein the microvalve device increases the pressure applied to said one of said brake band and said clutch, a pressure maintain position wherein the microvalve holds the pressure at a generally constant level to said one of said brake band and said clutch, and a pressure decrease position wherein the microvalve device decreases the pressure applied to said one of said brake band and said clutch, to control passage of pressurized fluid from said source to said one of a hydraulically operated brake band and a hydraulically operated clutch.