A method and apparatus for determining the engagement state of a clutch

摘要

A method and apparatus for determining the engagement state of a clutch 2 is disclosed in which the position of a slave cylinder piston 62 is measured by a sensor 63 and compared with a calculated displacement threshold value XTHRES. If the measured displacement of the slave cylinder piston 62 is less than the displacement threshold value then this is used as an indication that the clutch 2 is engaged and if the measured displacement of the slave cylinder piston 62 is greater than the displacement threshold value XTHRES then this is used as an indication that the clutch 2 is disengaged. This determination of clutch engagement state can be advantageously used in a stop-start system to permit the engine 10 to be started while a transmission 11 is in gear and it can also be used to prevent engine shutdown if the clutch 2 is not fully disengaged.