Abstract: A hydrodynamic friction clutch may include a rotatably mounted shaft, a drive disc non-rotatably fixed on the shaft, and an output body rotatably fixed on the shaft. The drive disc may include a radially extending annular transmission region for receiving a viscous fluid and via which the drive disc may be couplable to the output body for transmitting a torque, and an annular segment-shaped storage chamber for receiving the viscous fluid. The transmission region may be fluidically connected to the storage chamber via an inlet path and a drainage path. In the inlet path, a closable valve opening for controlling the quantity of the viscous fluid in the transmission region may be provided. The inlet path may include an annular segment-shaped communication passage, which may fluidically connect the storage chamber to the valve opening. The drainage path may fluidically connect to the inlet path at the valve opening.

Abstract: A hydrodynamic friction clutch may include a rotatably mounted shaft, a drive disc non-rotatably fixed on the shaft, and an output body rotatably fixed on the shaft. The drive disc may include a radially extending annular transmission region for receiving a viscous fluid and via which the drive disc may be couplable to the output body for transmitting a torque, and an annular segment-shaped storage chamber for receiving the viscous fluid. The transmission region may be fluidically connected to the storage chamber via an inlet path and a drainage path. In the inlet path, a closable valve opening for controlling the quantity of the viscous fluid in the transmission region may be provided. The inlet path may include an annular segment-shaped communication passage, which may fluidically connect the storage chamber to the valve opening. The drainage path may fluidically connect to the inlet path at the valve opening.

Abstract: A fluid friction clutch, in particular for a motor vehicle fan, having a rotatably mounted shaft wherein a reservoir for at least largely holding the fluid is provided radially inside an outer periphery of the drive body, and wherein at least one first flow path and at least one second flow path are provided, which are used to connect the reservoir to the coupling area, and wherein the drive body, at the outer periphery, has at least one flow resistance element which is arranged between the at least first flow path and the at least second flow path, and wherein furthermore there is a controllable device for closing and opening at least one of these flow paths.