Fluid-filled elastic mount having orifice passages tuned to damp input vibrations in respective different frequency ranges

A fluid-filled elastic mount comprising:

• a first and a second mounting member which are spaced apart from each other;
• an elastic body elastically connecting said first and second mounting members and partially defining a pressure-receiving chamber which receives an input vibrational load and which is filled with a non-compressible fluid;
• a flexible diaphragm which partially defines an equilibrium chamber filled with said fluid, said flexible diaphragm being displaceable to permit a change in volume of said equilibrium chamber;
• means for defining a first orifice passage for effecting fluid communication between said pressure-receiving and equilibrium chambers, said first orifice passage being tuned to a first frequency range;
• a movable member disposed between said pressure-receiving and said equilibrium chambers, said movable member being displaceable or deformable so as to permit relative volume changes of said pressure-receiving and said equilibrium chambers;
• means for defining a second orifice passage and a third orifice passage formed between said movable member and one of said pressure-receiving and said equilibrium chambers for permitting fluid flows therethrough based on displacement or deformation of said movable member, said second orifice passage being tuned to a second frequency range which is higher than said first frequency range while said third orifice passage is tuned to a third frequency range which is higher than said second frequency range;
• and
• first control means for permitting or inhibiting the fluid flows through said third orifice passage.