Method for Controlling a Hydrodynamic Retarder which can be Disengaged Mechanically Via a Separating Clutch

A method for controlling a hydrodynamic retarder which can be disengaged mechanically via a separating clutch in a motor vehicle, which comprises:

• a rotating bladed rotor and a bladed stator or a rotating bladed rotor and a bladed counter-rotor rotating in opposite direction thereto, which together form a working chamber filled with working medium in braking operation and emptied of working medium in non-braking operation, wherein the rotor is driven in braking operation via a drive train with a closed separating clutch and the working chamber is emptied when passing from the braking operation to the non-braking operation and the separating clutch opens, wherein the transition from the braking operation to the non-braking operation is initiated via a retarder switch-off request of a driver assistance system or via actuation of an input device by the vehicle driver;
• wherein:
• after determining the presence of a retarder switch-off request the separating clutch is kept closed for a preset time span and the working chamber of the retarder is emptied of the working medium by continuous actuation of the rotor and interruption of infeed of working medium into the working chamber, wherein the preset time span is varied according to at least one of the following parameters or at least one parameter correlated with one of the parameters and/or after determining the retarder switch-off request:
• the rotational speed of the rotor;
• an output pressure, against which the working medium is emptied from the working chamber;
• the filling level of the working chamber with working medium;
• the temperature of the working medium;
• the braking torque of the hydrodynamic retarder.

A method for controlling a hydrodynamic retarder which can be disengaged mechanically via a separating clutch in a motor vehicle, which comprises:

• a rotating bladed rotor and a bladed stator or a rotating bladed rotor and a bladed counter-rotor rotating in opposite direction thereto, which together form a working chamber filled with working medium in braking operation and emptied of working medium in non-braking operation, wherein the counter-rotor is driven in braking operation via a drive train with a closed separating clutch or the stator is supported stationary against a fixed component in braking operation with a closed separating clutch and the working chamber is emptied when passing from braking operation to non-braking operation and the separating clutch opens, wherein the transition from the braking operation to the non-braking operation is initiated via a retarder switch-off request of a driver assistance system or via actuation of an input device by the vehicle driver;
• wherein:
• after determining the presence of a retarder switch-off request the separating clutch is kept closed for a preset time span and the working chamber of the retarder is emptied of the working medium by continuous actuation of the rotor and interruption of infeed of working medium into the working chamber, wherein the preset time span is varied according to at least one of the following parameters or at least one parameter correlated with one of the parameters and/or after determining the retarder switch-off request:
• the rotational speed of the rotor;
• an output pressure, against which the working medium is emptied from the working chamber;
• the filling level of the working chamber with working medium;
• the temperature of the working medium;
• the braking torque of the hydrodynamic retarder.