Patent ID: 8874340

Claim:
A method of controlling an automated friction clutch, which is arranged as a starting and shifting clutch in a motor vehicle between a driveshaft ( 5 ) of a drive engine ( 4 ) and an input shaft ( 7 ) of a change-speed transmission ( 6 ), the friction clutch is passively engagable by a contact pressure spring ( 10 ) and which is disengagable and engagable by a simply acting pneumatic control cylinder ( 12 ), a control piston ( 13 ) of the control cylinder is in controlling connection with the contact pressure spring ( 10 ) and has a pressure chamber ( 14 ) that is connectable, via at least one controllable air inlet valve ( 15 ), to a compressed-air source ( 19 ), and, via at least one controllable air outlet valve ( 16 ), to a compressed-air sink ( 21 ), the method comprising the steps of: setting, via the contact pressure spring, a particular disengagement position of the friction clutch ( 3 ) in a regulating process as a function of a difference between a specified nominal position (x K — soll ) and an actual position (x K — ist ), determined by sensors, of either the control piston ( 13 ), or a transmission element arranged between the control piston ( 13 ) and the contact pressure spring ( 10 ), by alternatively opening the air inlet valve ( 15 ) and the air outlet valve ( 16 ), the air inlet valve ( 15 ) and the air outlet valve ( 16 ) are, in each case, opened in a sustained-pulse operating mode having a duration (Δt V ) that is calculated as a quotient of an air mass difference (Δm K ) between a nominal air mass (m K — soll ) present in the pressure chamber ( 14 ) of the control cylinder ( 12 ) when the control piston ( 13 ) is in the nominal position (x K — soll ) and the actual air mass (m K — ist ) present therein when the control piston ( 13 ) is in the actual position (x K — ist ) (Δm K =m K — soll −m K — ist ) and an air mass flow (m v ) passing through the inlet and the outlet valve ( 15 ; 16 ) concerned, which depends on an existing pressure situation and on flow characteristics of the open air inlet valve or the air outlet valve ( 15 , 16 ) (Δt V =Δm K /m V ).