2 April 2015 Design of energy-efficient MRF-based clutches with defined fail-safe behavior for integration in hybrid powertrains
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Drag losses in the powertrain are a serious deficiency for any energy-efficient application, especially for hybrid electrical vehicles. A promising approach for fulfilling requirements like efficiency, wear, safety and dynamics is the use of an innovative MRF-based clutch design for the transmission of power that is based on magnetorheological fluids (MRF). MRF are smart fluids with the particular characteristics of changing their apparent viscosity significantly under influence of the magnetic field. Their characteristics are fast switching times and a smooth torque control in the powertrain. In this paper, a novel clutch concept is investigated that facilitates the controlled movement of the MRF from an active torque-transmitting region into an inactive region of the shear gap. This concept enables a complete disengagement of the fluid engaging surfaces in a way that viscous drag torque can be eliminated. Therefore, a simulation based design for such MRF-based clutches is used to design the required magnetic excitation systems for enabling a well-defined safety behavior by the fluid control. Based on this approach, an MRF-based clutch is developed in detail which provides a loss-reduced alternative to conventional disengagement devices in the powertrain. The presented MRF-based clutch enables a investigation of different systems in one design by changing the magnetic excitation. Especially, different possibilities for the fail-safe behavior of the MRF-based clutch are considered to ensure a well-defined condition in electrical or hybrid powertrains in case of a system failure.
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Vadim Erbis, Vadim Erbis, Christian Hegger, Christian Hegger, Dirk Güth, Dirk Güth, Jürgen Maas, Jürgen Maas, "Design of energy-efficient MRF-based clutches with defined fail-safe behavior for integration in hybrid powertrains", Proc. SPIE 9431, Active and Passive Smart Structures and Integrated Systems 2015, 94310A (2 April 2015); doi: 10.1117/12.2085117; https://doi.org/10.1117/12.2085117

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