Bearing member, and vibration damping device using same

A vibration damping device serving as a variable damping force damper, the vibration damping device comprising:

• a cylinder;
• a piston rod inserted into the cylinder;
• a piston connected to the piston rod and disposed axially slidably in the cylinder;
• a first liquid chamber and a second liquid chamber partitioned in the cylinder by the piston and filled with a magneto-rheological fluid composition;
• a communication hole formed in the piston so as to communicate the first liquid chamber and the second liquid chamber;
• and
• an electromagnetic coil for applying a magnetic field to the magneto-rheological fluid composition flowing through the communication hole, wherein
• the piston rod is slidably supported by a bearing member disposed in the cylinder,
• the bearing member comprises a resin layer on a side defined as a friction sliding surface of a base member,
• the resin layer comprises polytetrafluoroethylene and a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin,
• the resin layer further comprises a solid lubricant and/or an inorganic filler,
• the base member is made of a steel material,
• the resin layer is impregnated and coated on a porous metal layer formed on the base member, and
• the bearing member is lubricated by the magneto-rheological fluid composition.