Patent ID: 7578743

Claim:
A torsional vibration dampener for dampening torsional vibrations of a rotationally driven shaft, comprising: a hub that is adapted to be coaxially connected to said shaft relative to an axis of rotation thereof so as to rotate with said shaft; a rubber elastic ring connected to said hub; and a rotationally symmetrical body of inertia that is connected to said rubber elastic ring and acts as a vibrational mass, wherein said body of inertia comprises a primary part and a secondary part, wherein said secondary part is coaxial relative to said primary part and is pivotable about a given angle relative to said primary part, wherein displacement chambers are formed by and are disposed between said primary part and said secondary part, wherein at least two of said displacement chambers communicate with one another via at least one flow control gap, wherein relative movement between said primary part and said secondary part alters the volumes of each two displacement chambers that communicate with one another via said flow control gap such that the volume of one of said displacement chambers decreases by the same amount by which the volume of the other of said displacement chambers increases, wherein said displacement chambers are filled with a hydraulic fluid such that a fluid coupling is formed between said primary part and said secondary part, wherein upon a relative movement between said primary and said secondary part, due to the resulting change in volume of said displacement chambers hydraulic fluid flows from the one displacement chamber into the other displacement chamber via said flow control gap, wherein said displacement chambers are provided with supply means and discharge means for said hydraulic fluid, wherein via said supply means, hydraulic fluid under pressure is continuously supplied from a storage reservoir, wherein excess hydraulic fluid flows back from said displacement chambers, via said discharge means, into said storage reservoir, and wherein said supply means to said displacement chambers, and said discharge means from said displacement chambers, are embodied such that upon relative movement between said primary part and said secondary part hydraulic fluid predominantly flows only between said displacement chambers that communicate with one another via said at least one flow control gap.