Clutches and Brakes

Magnetorheological fluids (MRF) can be used to create clutches and brakes in which the transmittable torque can be infinitely adjusted by the magnetic field strength. The torque is transmitted from an input shaft via the stiffened MRF to the output shaft. An essential advantage is the low-wear transmission principle, as no fixed clutch discs rub against each other. This means that a soft coupling is always possible. The MRF transmission medium also has a damping effect. Due to the adjustability of the maximum transmittable torque, the principle is particularly suitable for safety clutches whose maximum torque is to be limited.

The design of an MRF coupling can be very versatile. This allows MRF couplings to be realized for both low and high torques. MRF couplings with transmittable torques of 500 Nm and more are possible. An MRF clutch with a high transmittable torque is shown in the figure below.

Competences:

  • Composition-property correlations of MRF
  • Conception and design of MRF clutches/brakes
  • Simulation of magnetic circuits, also with permanent magnets
  • Characterization of MRF clutches/brakes
     

Offer:

  • Development of customized MRF clutches/brakes
  • Development of special MRF for switchable clutches/brakes
  • Construction of demonstrators for MRF clutches/brakes
  • Magnetic circuit design for MRF clutches/brakes, also with permanent magnets
  • Design of MRF clutches/brakes
  • Development of application-oriented testing technology for MRF clutches/brakes
Test bench with MRF coupling.
© Fraunhofer ISC
Test bench with MRF coupling.
MRF clutch with high transmittable torque in test bench.
© Fraunhofer ISC
MRF clutch with high transmittable torque in test bench.
Transmittable torque of an MRF clutch with high transmittable torque as a function of the coil current.
© Fraunhofer ISC
Transmittable torque of an MRF clutch with high transmittable torque as a function of the coil current.