Fluid filled active vibration damping device

1. A fluid filled active vibration damping device comprising:

a first mounting member;

a second mounting member;

a rubber elastic body elastically connecting the first and second mounting members;

a pressure receiving chamber having a non-compressible fluid sealed therein and undergoing input of vibration, the pressure receiving chamber being defined at one part by the rubber elastic body, and at another part by an excitation plate capable of displacement;

an electromagnetic actuating assembly disposed on an opposite side from the pressure receiving chamber with the excitation plate being located therebetween; and

an output member;

wherein:

the excitation plate is subjected to actuating force of the output member actuated by application of electrical current to a coil member in the electromagnetic actuating assembly, thereby exciting the excitation plate in order to control a pressure in the pressure receiving chamber;

the output member projects out towards the excitation plate from the electromagnetic actuating assembly, and a permanent magnet is disposed in at least one of the output member and the excitation plate, the permanent magnet generating an attractive magnetic force that couples the output member and the excitation plate; and

the permanent magnet is disposed on one of the output member and the excitation plate, and a magnetic member comprising ferromagnetic material is disposed on an other of the output member and the excitation plate, while the output member and the excitation plate are coupled by means of superimposing a magnetic pole produced by the permanent magnet, against the ferromagnetic material.

2. A fluid filled active vibration damping device according to claim 1 , wherein the output member and the excitation plate have respectively faces superimposed against each other and coupled utilizing magnetic force, each face being designed as a flat surface extending orthogonal to a direction of displacement of the output member.

3. A fluid filled active vibration damping device according to claim 2 , wherein one of the flat surface of the output member or the flat surface of the excitation plate is constituted as a magnetic pole face at which is positioned a magnetic pole produced by the permanent magnet; and an other one of the flat surface of the output member and the flat surface of the excitation plate side is constituted as a magnetic force acting face composed of ferromagnetic material, the magnetic force acting face having a larger flat shape than the magnetic pole face.

4. A fluid filled active vibration damping device according to claim 1 , further comprising: a variable volume equilibrium chamber partially defined by a flexible film and having the non-compressible fluid sealed therein; and an orifice passage formed to connect the equilibrium chamber to the pressure receiving chamber.

5. A fluid filled active vibration damping device according to claim 4 , wherein the flexible film is fastened fluid tightly at an outer peripheral edge portion thereof to the second mounting member; and a coupling portion is disposed perforating fluid tightly through a center portion of the flexible film from the excitation plate and projecting towards the output member of the electromagnetic actuating assembly, and coupled with the output member.

6. A fluid filled active vibration damping device according to claim 1 , wherein:

a yoke member is disposed around the permanent magnet, and

both of two magnetic poles of the permanent magnet are located at an interface where a surface of the output member contacts a surface of the excitation plate.