A damper system for a vehicle which is mounted on the vehicle and which comprises an electromagnetic damper configured to generate a damping force with respect to a motion of a sprung portion and an unsprung portion toward each other and a motion thereof away from each other,
- wherein the electromagnetic damper includes:
- an electromagnetic motor;
- a motion converting mechanism configured to convert the motions of the sprung portion and the unsprung portion toward and away from each other into a motion of the electromagnetic motor and vice versa;
- and
- an external circuit disposed outside the electromagnetic motor and including (A) a first connection passage in which an electric current is allowed to flow from a first terminal as one of two terminals of the electromagnetic motor to a second terminal as the other of the two terminals while an electric current is prohibited from flowing from the second terminal to the first terminal and (B) a second connection passage in which the electric current is allowed to flow from the second terminal to the first terminal of the electromagnetic motor while the electric current is prohibited from flowing from the first terminal to the second terminal,
- wherein the electromagnetic damper is configured to generate the damping force that depends on an electromotive force of the electromagnetic motor, with respect to the motion of the sprung portion and the unsprung portion toward each other by permitting a generated current by the electromagnetic motor to flow through the first connection passage and with respect to the motion of the sprung portion the unsprung portion away from each other by permitting the generated current by the electromagnetic motor to flow through the second connection passage,
- wherein the external circuit further includes:
- (C) a first-connection-passage-current adjuster provided in the first connection passage and configured to adjust the electric current that flows from the first terminal to the second terminal;
- and (D) a second-connection-passage-current adjuster provided in the second connection passage and configured to adjust the electric current that flows from the second terminal to the first terminal,
- wherein the damper system comprises an external-circuit controller configured to control an electric current that flows in the electromagnetic motor by controlling the external circuit,
- wherein the external-circuit controller is configured to control the generated current caused by the motion of the sprung portion and the unsprung portion toward each other by controlling the first-connection-passage-current adjuster and to control the generated current caused by the motion of the sprung portion and the unsprung portion away from each other by controlling the second-connection-passage-current adjuster, and
- wherein the external-circuit controller includes:
- (a) a main-adjuster control portion which is configured to designate the first-connection-passage-current adjuster as a main adjuster where a sprung-resonance-frequency-range component that is a component of a relative vibration of the sprung portion and the unsprung portion in a sprung resonance frequency range is a value indicative of the motion of the sprung portion and the unsprung portion toward each other, to designate the second-connection-passage-current-adjuster as the main adjuster where the sprung-resonance-frequency-range component is a value indicative of the motion of the sprung portion and the unsprung portion away from each other, and to perform, on one of the first-connection-passage-current adjuster and the second-connection-passage-current adjuster that is designated as the main adjuster, a first control for mainly damping the relative vibration of the sprung portion and the unsprung portion;
- and
- (b) an auxiliary-adjuster control portion which is configured to designate the second-connection-passage-current adjuster as an auxiliary adjuster where the sprung-resonance-frequency-range component is the value indicative of the motion of the sprung portion and the unsprung portion toward each other, to designate the first-connection-passage-current adjuster as the auxiliary adjuster where the sprung-resonance-frequency-range component is the value indicative of the motion of the sprung portion and the unsprung portion away from each other, and to perform, on one of the first-connection-passage-current adjuster and the second-connection-passage-current adjuster that is designated as the auxiliary adjuster, a second control for assisting the damping of the relative vibration of the sprung portion and the unsprung portion by the first control.