Magnetorheological fluid damper tunable for smooth transitions

• Main Authors: HOPKINS PATRICK N, LUKUC MICHAEL R, LISENKER IIYA
• Format: Patent
• Language: English
• Published: 20.11.2001
• Edition: 7
• Subjects: BLASTING; ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVEFUNCTIONING OF MACHINES OR INSTALLATIONS; HEATING; LIGHTING; MEANS FOR DAMPING VIBRATION; MECHANICAL ENGINEERING; PERFORMING OPERATIONS; SHOCK-ABSORBERS; SPRINGS; THERMAL INSULATION IN GENERAL; TRANSPORTING; VEHICLE SUSPENSION ARRANGEMENTS; VEHICLES IN GENERAL; WEAPONS

An improved magnetorheological fluid damper is provided which effectively provides a smooth transition, without a sharp break in the damper force/velocity curve, between very low damping forces near zero damper velocity to higher damping forces at higher piston velocities while maintaining desirable maximum force levels. The damper includes a piston assembly, including a magnet assembly and a flow gap extending through the piston assembly to permit fluid flow between the chambers. The force/velocity optimization feature includes a groove or passage open to the flow gap, positioned in series with a part of the flow gap in a magnetic circuit generated by the magnet assembly and dimensioned/sized to permit fluid flowing the passage to experience a magnetorheological effect less than a magnetorheological effect experienced by fluid flowing through the flow gap but not through the groove. Preferably, the passage is formed in an inner annular surface of a flux ring positioned around a piston core. The passage may be a single passage or multiple passages and may be formed, for example, by a curvilinear surface, a modified rectangular surface and/or a triangular surface or combinations of surfaces.