Brakes and clutches using ER fluids

Abstract

If an electro-rheological (ER) fluid is used in viscous coupling devices, such as clutches or brakes, then the possibility to control the output capacity of this device exists. The imposition of an electric field between the input and output parts alters the viscosity of the fluid and consequently the output torque for brakes or angular velocity for the clutches. In this paper the experimental investigation of a multiple disk electro-rheological viscous device, that can for experimental purposes be used as both brake and clutch, is presented. The device used has 10 pairs of rotating and stationary (or rotated) disks with 1 mm disk spacing. The apparatus is filled with ER fluid and an electric field of 0–2.1 kV\\mm is applied. The ER fluid used is zeolite with oil. The input shaft speed can be changed from 0–2400 rpm using a 3 kW variable speed motor. In this paper, the driven shaft with its fixed disks is clamped with the aid of a beam on a spring measuring system in order to measure the resulting torque. As a consequence of this experimental configuration, the energy dissipation is high. As the temperature is increased, the viscosity is decreased. On the other side, as the applied electric field is increased the viscosity is also increased. So properties such as the torque capacity of the device, the wall shear stress and relative viscosity are experimentally determined and presented as functions of the two main parameters, electric field and temperature, as well as the input angular velocity.