Fluid couplings

Claim 1

A fluid coupling comprising: a driving member and a driven member mounted for rotation relative to one another; means forming a drive chamber receiving one of said members and formed by at least a part of the other of said members. means forming a reservoir separate from said drive chamber, means forming a passage from said drive chamber to said reservoir, means forming an outlet port from said reservoir to said drive chamber, a viscous liquid contained within said reservoir, said liquid being adapted to pass through said port to said drive chamber for transmitting torque between said members and pass through said passage to said reservoir; a valve arm pivotally mounted on one of said members and having a closure member at one end thereof, said valve arm being displaceable between a closed position in which the closure member seats against said port to prevent flow of liquid into said drive chamber and an open position in which the closure member is spaced from said port in the direction of liquid flow from said reservoir, means for yieldably biasing said valve arm toward said closed position; means for displacing said valve arm toward said open position in response to a single variable parameter external to the coupling; the geometry of the valve arm and the pivotal mounting thereof being so arranged that centrifugal force generated upon rotation of the coupling acts to apply a turning moment on the valve arm urging it toward the closed position in opposition to the centrifugally created pressure force of liquid acting to urge the valve arm toward the open position; whereby the operation of said valve is rendered insensitive to the R.P.M. of said coupling.