In this contribution a study is carried out for a defined variation of a moving mass based on magnetorheological fluids (MRF). Magnetorheological fluids consist out of a carrier fluid (synthetic-oil) with suspended carbonyl iron powder particles and additives. By magnetically induced volume forces the MRF can be controlled, moved, spatially placed and safely attached at moving parts in order to increase the moving mass on the hand. On the other hand it can be removed and placed in a resting position, like at a housing for example. Among other application this can be utilized in order to change the eigenfrequency of oscillating systems. After introducing appropriate concepts a simulation-based development of a demonstrating prototype for the movement of the MRF will be shown, considering certain designs of magnetic circuits consisting out of permanent magnets and electromagnets on the mover and on the stator. The magnetic designs allows the realization and by this the investigation of the before mentioned behaviors. For the determination of the movement of the MRF multiphysical simulations are carried out. In addition, the developed design is realized to investigate the approach experimentally, too.
In this contribution a design for the enhancement of the torque capacity of energy efficient MRF-based coupling elements will be presented. Magnetorheological fluids (MRF) are smart fluids, consisting of fine magnetic particles in an oil based carrier fluid, with the particular characteristics of changing their apparent viscosity significantly under the influence of a magnetic field. This property allows the design of mechanical devices for torque transmission, such as brakes and clutches, with a continuously adjustable torque generation. Applying the MR-fluid movement control viscous induced drag torques can be eliminated. In combination with a smart MRF-based sealing also losses due to the sealing can be significantly reduced above a well-defined rotational speed increasing the energy efficiency considerably. In addition, the serpentine flux guidance offers an attractive design saving space, weight and feeding energy. For a further enhancement of the torque density certain different possibilities arise. Beside a strengthening due to a combined squeeze and shear mode a design based on multiple axial shear gaps was shown before. Here the most appropriate design will be investigated in more detail. Simulations based on a multiphysic-FEA will be performed and a detailed investigation of the torque enhancement compared to a MRF-based coupling elements with a single shear gap and same outer dimensions will evaluate the degree of torque enhancement.
The requirements for transmission and coupling elements are rising continuously. Our previous investigations were focused on the elimination of viscous induced drag-torques in coupling elements based on magnetorheological fluids by a MR-fluid movement control. For a further reduction of weight and space requirements a design of a magnetic circuit with a serpentine flux guidance was introduced last year. For a further enhancement of the torque density a design based on multiple shear gaps is proposed in this contribution. Due to the MR-fluid movement control using partially filled shear gaps a simple arrangement of several coaxial shear gaps is not applicable. Instead, each shear gap has to be separated by a novel MR-fluid sealing, which allows also a drag- torque free operation above certain rotational speeds. Combining these features result in a MRF-based coupling element with an enhanced torque density at simultaneously reduced drag-torque.
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