Patent ID: 7954616

Claim:
A fluid friction clutch having a housing and having a clutch plate which is arranged so as to be rotatable relative to the housing and is rotationally fixedly arranged on an end of a shaft which is mounted centrally within the housing, which shaft supports, at its other end, an active element which is to be driven by the clutch, with a working chamber which can be pressurized with clutch fluid being formed between the housing and the clutch plate, having a reservoir chamber, which is formed in the housing, for the clutch fluid, and having a supply duct which leads from said reservoir chamber to the working chamber, and having a back-pumping system for returning the clutch fluid from the working chamber to the reservoir chamber with a valve arrangement for controlling the clutch fluid which is supplied to the working chamber being arranged in the supply duct characterized in that the housing is connected to a drive element, is arranged so as to be rotatable relative to a stationary clutch part and forms the primary side of the clutch, with clutch fluid flowing from the reservoir chamber, through the supply duct which runs substantially radially outward from the latter, to the working chamber as the driven housing rotates, in that a radial gap is formed between the housing and the outer edge of the clutch plate, and in that the back-pumping system comprises a scraping element, which is arranged on the stationary clutch part at that side of the clutch plate which faces away from the working chamber, for the clutch fluid, which scraping element has an accumulation edge member and a duct, said duct opening in said accumulation edge member and in communication with the reservoir chamber.