Active damper

1. An active damper interposed between a vibrating source and a vibration-receiving part that receives vibrations of the vibrating source, comprising:

an elastic support body connected to the vibrating source;

a first wall section which is provided at the elastic support body and defines a first liquid chamber;

a second wall section which is provided on an opposite side of the first liquid chamber than the first wall section and defines a second liquid chamber;

a partition wall section which separates the first liquid chamber from the second liquid chamber;

an orifice which is disposed at the partition wall section and through which liquid passes between the first liquid chamber and the second liquid chamber; and

a damping unit configured to attenuate the vibrations transmitted from the vibrating source to the vibration-receiving part,

the damping unit comprising:

an excitation coil configured to generate a magnetic field, a strength of which depends on an amplitude of a current supplied;

a unit of magnetic members configured to form a circular closed magnetic circuit, which is a path for the magnetic field generated by the excitation coil, the unit having an annular member and a central member facing each other in diametrical directions; and

a magneto-viscoelastic elastomer, a viscoelasticity of which changes depending on the strength of the magnetic field generated by the excitation coil and which is provided in the closed magnetic circuit formed of the unit of magnetic members, ends of the magneto-viscoelastic elastomer are connected to the annular member and the central member of the unit, respectively, so that the magnetic field is applied to the magneto-viscoelastic elastomer in the diametrical directions, wherein

at least one of the second wall section and the partition wall section is provided with the damping unit.

2. The active damper according to claim 1 , wherein

one of the magnetic members of the unit of magnetic members of the damping unit includes a portion extending in a direction crossing an input direction of vibrations inputted from the vibrating source and

the magneto-viscoelastic elastomer of the damping unit is provided in an opening portion created at an extended portion between the magnetic members.

3. The active damper according to claim 2 , wherein

the opening portion created between the magnetic members has an annular shape; and

the magneto-viscoelastic elastomer of the damping unit is disposed radially so as to occupy the opening portion.

4. The active damper according to claim 2 , wherein

the partition wall section is provided with the damping unit; and

the magneto-viscoelastic elastomer of the damping unit is provided to a part of the magnetic members facing the first liquid chamber in the opening portion.

5. The active damper according to claim 2 , wherein

the second wall section is provided with the damping unit; and

the magneto-viscoelastic elastomer of the damping unit is provided to a part of the magnetic members facing the second liquid chamber in the opening portion.

6. An active damper interposed between a vibrating source and a vibration-receiving part that receives vibrations of the vibrating source, comprising:

an elastic support body connected to the vibrating source;

a first wall section which is provided at the elastic support body and defines a first liquid chamber;

a second wall section which is provided on an opposite side of the first liquid chamber than the first wall section and defines a second liquid chamber;

a partition wall section which separates the first liquid chamber from the second liquid chamber;

an orifice which is disposed at the partition wall section and through which liquid passes between the first liquid chamber and the second liquid chamber; and

a damping unit configured to attenuate the vibrations transmitted from the vibrating source to the vibration-receiving part,

the damping unit comprising:

an excitation coil configured to generate a magnetic field, a strength of which depends on an amplitude of a current supplied;

magnetic members configured to form a circular closed magnetic circuit, a path for the magnetic field generated by the excitation coil; and

a magneto-viscoelastic elastomer, a viscoelasticity of which changes depending on the strength of the magnetic field generated by the excitation coil and which is provided in the closed magnetic circuit formed of the magnetic members,

wherein

at least one of the first wall section, the second wall section, and the partition wall section is provided with the damping unit,

the damping unit comprises first and second damping units;

the partition wall section is provided with the first damping unit and the second wall section is provided with the second damping unit, the first and second damping units having substantially the same configuration;

each of the first and second damping units has a portion of the magnetic members extending in a direction crossing an input direction of the vibrating source-derived vibrations; and

a first magneto-viscoelastic elastomer of the first damping unit is provided to a part of the magnetic members of the first damper facing the first liquid chamber in the opening portion, and the second magneto-viscoelastic elastomer of the second damping unit is provided to a part of the magnetic members of the second damper facing the second liquid chamber in the opening portion.

7. The active damper according to claim 6 , wherein

a strength of a magnetic field acting on the first magneto-viscoelastic elastomer differs from a strength of a magnetic field acting on the second magneto-viscoelastic elastomer.

8. The active damper according to claim 1 , wherein

the damping unit is provided with a mass weight member for adjusting a specific value for the vibrations.

9. The active damper according to claim 1 , wherein

the vibrating source is an engine installed in a vehicle;

the vibration-receiving part is a vehicle body frame of the vehicle; and

the active damper is used when the engine is mounted on the vehicle body frame.