A multi-gap magnetorheological clutch with permanent magnet

Abstract

This paper describes the design and testing of a novel Permanent Magnet (PM) clutch based on Magneto-Rheological Fluid (MRF). It was inspired by a prototype previously developed by the authors and contains a novel gap shape conceived to reduce the torque loss in the disengaged operating mode. Several geometries and material arrangements were investigated and the performance in terms of transmissible torque in different operating conditions were assessed by FE numerical models. The prototype was manufactured and some experimental tests were performed. The new prototype was rated on the basis of performance indices and the design effectiveness was proved by a higher value of efficiency in the disengaged operating mode.

An innovative multi-gap clutch based on magneto-rheological fluids and electrodynamic effects: magnetic design and experimental characterization

“…Anyhow, a detailed description is reported in [1,8]. As shown in figure 1 it was composed of a primary and a secondary shaft, of a a double cup-shaped gap, filled with MRF, and of a permanent magnets excitation system (PMs), which can slide axially in the housing chamber.…”

“…As described in [1], this configuration was designed to force the magnetic flux density B to pass through the inner and outer MRF gap, allowing a better field distribution inside the MR fluid itself.…”

“…magnetized state (and vice versa), the clutch actuation was within the time-response requirements. The device developed in [1] was investigated and designed by means a proper 3D FEM model. Furthermore it was experimentally characterized by performing a set of measurements on a dedicated test bench.…”

“…Although the developed prototype [1] operates quite well [7], its main drawback is the value of the transmissible torque in the starting phase, that is during the mechanical transient between the disengaged and the engaged condition. A shown in figure 3(b), the torque in the engaged condition is almost constant as a function of the relative speed (DW) between the two clutch shafts.…”

Controllable Magnetoactive Polymer Conduit

“…The influence of an external magnetic field can produce changes in Young's modulus of over 10 6 % (colossal magneto-rheological effect) [2]. In addition to dramatic changes in mechanical storage and loss moduli, changes in electrical properties are also measurable [3].…”