Patent ID: 7510060
Filing Date: 2009-03-31
Classification: F16F

Abstract:
1. A damper with a controllable variable damping force, the damper comprising: a piston having a piston body; a cylinder provided with a magnetic viscous fluid and the piston therein, wherein an entire outer radial peripheral surface of the piston body relative to a longitudinal axis of the piston body slidingly engages an inner peripheral surface of the cylinder, and wherein an interior of the cylinder is divided into a first fluid chamber and a second fluid chamber by the piston; a fluid passage that passes through the piston body and places the first fluid chamber in communication with the second fluid chamber; a coil provided in the piston body and which is energized for operation of the damper by an electric current supplied by a controller, wherein a viscosity of the magnetic viscous fluid in the fluid passage is changed by the coil being energized by the controller; an electric current supply circuit which supplies a predetermined constant electric current to the coil when the electric current supplied by the controller fails to be supplied to the coil; and a sub-coil provided in the piston body, wherein the sub-coil is disposed in parallel relative to the coil, and wherein the controller supplies a predetermined constant electric current to the sub-coil whenever the coil is not operating properly with the electric current supplied by the controller, wherein a magnetic flux generated by the sub-coil influences the slide movement of the piston in the cylinder in opposite directions in place of said coil.