The clutch system relates to an automatic friction clutch with a hydrostatically actuator-controlled clutch withdrawal. In such clutch release systems, a slave cylinder pressurized by a master cylinder in an engaged state is in connection with a reservoir (tank) via a connection opening uncovered by the master cylinder piston. To determine the opening deviations and location of the connection opening, it is proposed that actuation of master cylinder be velocity-dependent and pressure patterns of the hydrostatic clutch release system be evaluated.
1. A clutch system with friction clutch automatically actuated by an actuator having a hydrostatic clutch withdrawal system, comprising:
a control unit activating the actuator;
a slave cylinder; and
a master cylinder connected with and pressurizing said slave cylinder through a line, the master cylinder including a resting state, wherein a master cylinder piston is positioned to uncover a connection opening to a reservoir, and the master cylinder piston is actuated according to a pressure pattern to cover and uncover the connection opening at different actuation travels,
wherein pressure patterns of the clutch withdrawal system are determined and dependent upon an actuation velocity of the master cylinder piston, and
wherein, in the pressure pattern of the master cylinder piston, starting from the resting state, cycles of fast and slow actuations of the master cylinder piston are performed in an actuation direction with increasing displacement from a starting point in the actuation direction, in order to determine closure of the connection opening through a distance that tends to zero relative to an actuation travel.
2. The clutch system according to claim 1 , wherein the master cylinder piston is actuated at least at two different velocities when actuated according to the pressure pattern such that the connection opening is transformed from an uncovered state and a covered state by the master cylinder piston.
3. The clutch system according to claim 2 , wherein the pressure patterns are evaluated by means of a pressure sensor disposed on the clutch withdrawal system.
4. The clutch system according to claim 2 , wherein the pressure patterns are determined by comparison of locations of a sensing point on the friction clutch after the master cylinder passes over the connection opening at different velocities.
5. The clutch system according to claim 1 , wherein the connection opening is opened and closed by means of a snifting groove located on one side of the master cylinder piston and in connection with a U-seal fixed on a housing and dependent on distance covered by the master cylinder piston.