Fichtel & Sachs Ag

Werner Gob

Gerd Brunken

Dieter Neugebauer

Peter Anders

Oswald Reis

The fluid friction clutch for the cooling fan of an internal combustion engine carries, on the front of its housing, a bimetallic element on the longitudinal ends of which flexible retaining tabs are formed. The retaining tabs are bent over towards the front and riveted with the front. The securing of the bimetallic element is especially durable.

Fluid friction clutch

The fluid friction clutch, especially fan clutch, comprises for the temperature-dependent controlling of its shear fluid cycle a bimetallic element (35) which is to be displaced in its longitudinal direction for installation in a retaining fitting (37). A clip (63) fitted on to the retaining fitting (37) after the installation of the bimetallic element (35) blocks the path of introduction of the bimetallic element (35) and thus secures the bimetallic element (35) against unintentional release out of the retaining fitting (37).

A viscous fan coupling unit is controlled by a bimetallic strip. The bimetallic strip is subdivided by an elongate slot into two partial strips. The partial strips are interconnected by end portions of the bimetallic strip and by a cross-piece. The cross-piece acts on a control pin of the viscous fan coupling. This bimetallic stream reacts immediately on temperature changes of the air strip passing around the bimetallic strip. By the slot internal stresses are avoided such that the bimetallic strip can provide larger deflection paths and larger control forces in response to temperature changes.

Viscous fan coupling unit

The temperature-dependently controllable fluid friction clutch comprises a temperature-control device for the shear fluid circulation, with a bimetallic element (35) held on an end wall of the housing (7) and coupled, through a pin (39) freely displaceably guided in a bore (37), with a valve (25, 27) of the temperature-control device. To seal the pin (39) in relation to the housing (7) on the part of the pin (39) issuing from the housing (7) there is set a sealing element (41) which rests under axial stress through a sealing flange (43) of substantially annular disc form on a sealing surface (45) extending transversely of the axis (1) of rotation. The sealing flange (43) has substantially the form of a relatively shallow or flat frusto-conical shell widening towards the sealing surface (45) and is stressed substantially only to flex elastically. In this way friction forces between the pin (39) and the bore (37) can be reduced, which improves the accuracy of the temperature control.

Temperature-dependently controllable fluid friction clutch

The fluid friction clutch comprises a clutch input part drivable about a rotation axis and a clutch output part rotatable coaxially in relation to the clutch input part. The clutch output part together with the clutch input part defines at least one shear gap. A cover which forms a cavity enclosing at least the region of the shear gap is filled partially with viscous fluid and otherwise with gas. The gas-filled volume of the cavity contains less than 18 percent of oxygen by volume, preferably not more than 5 percent of oxygen by volume, in order to preclude a chemical reaction of the viscous fluid with the oxygen under thermal overloading which limits the utility of the viscous fluid. To reduce the proportion of oxygen either the cavity is evacuated or it is filled with a substantially oxygen-free protective or noble gas.

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Kurnach, Germany

Werner Gob