Abstract: A rotary damper assembly comprises a housing extending along a center axis. The housing includes an upper portion and a lower portion. The lower portion defines a fluid chamber. The upper portion defines a compartment in communication with the fluid chamber. The magnetic field generator includes a magnetic core located between the upper portion and the lower portion. The magnetic core extends along the center axis between the upper portion and the lower portion. At least one coil extends about the magnetic core. A shaft extends along the center axis through the upper portion and the magnetic core and into the fluid chamber to facilitate magnetorheological fluid flow from the compartment to the fluid chamber. The magnetic field generator includes an insert, containing a permanent magnetic material, for generating a permanent magnetic field to change viscosity of the magnetorheological fluid.

Abstract: A rotary damper assembly comprises a housing extending along a center axis. The housing includes an upper portion and a lower portion. The lower portion defines a fluid chamber. The upper portion defines a compartment in communication with the fluid chamber. The magnetic field generator includes a magnetic core located between the upper portion and the lower portion. The magnetic core extends along the center axis between the upper portion and the lower portion. At least one coil extends about the magnetic core. A shaft extends along the center axis through the upper portion and the magnetic core and into the fluid chamber to facilitate magnetorheological fluid flow from the compartment to the fluid chamber. The magnetic field generator includes an insert, containing a permanent magnetic material, for generating a permanent magnetic field to change viscosity of the magnetorheological fluid.