Electronic clutch control e.g. for vehicle automatic transmission - takes place in two stages with preparatory positioning of piston in hydraulic cylinder before pressure is increased

摘要

The input and output shafts are coupled together through two planetary gears with high, low and reverse clutches. The low clutch (50) is operated by an electronic control unit (74) with a timing magnetic valve (60) and a shifting magnetic valve (54). Subsequent to a first command, fluid is supplied to the hydraulic chamber (68) in sufficient quantity to move the piston (65) into a critical position ready to apply pressure to the clutch plates. A second command is followed by an increase in the pressure, which brings the plates into engagement. ADVANTAGE - The control does not require a complex and costly structure or an elaborate electronic control program.