Improvements to hydraulic antivibratory supports

Claim 1

An antivibratory device for insertion for support and shock absorbing purposes between two rigid elements, comprised by a sealed case having a rigid base which may be fixed to one of the two rigid elements, a rigid ring securable to the other rigid element, a resilient annular support wall sealingly connecting the base to the ring and a flexible membrane sealingly joined to the ring, the inside of this case being divided, by a rigid sealed dividing wall connected to the ring between the annular wall and the membrane, into two chambers, namely a work chamber on the annular wall side and a compensation chamber on the membrane side, these two chambers communicating together through a restricted passage with an adjustable aperture, and a liquid mass filling the two chambers as well as the restricted passage, the restricted passage defined at both ends by two fixed orifices opening respectively into the two chambers, for at least the maximum degree of opening of said passage, said passage being defined over at least a portion of its lateral periphery by a face of a rigid rotary valve housed between the two orifices and connected angularly to the rotor of a drive member for rotation about an axis to vary the cross-section of the passage, said valve being in the form of a relatively axially, thick, flat sector centered on the axis of rotation of the valve and housed in a cylindrical case which surrounds the valve and is of an inside shape which mates with the lateral outer periphery of the valve, the thickness of the valve, taken in the direction of alignment of the two orifices being equal to at least 10 mm, and wherein if "S" is the maximum opening cross-section of the restricted passage, the ratio between the thickness of the valve, taken in the direction of alignment of the two orifices and √S is at least equal to 0.3.