Investigation of Eddy Current Brakes for Improvement of Braking Torque Reduction at High Speeds

Currently, contact-type disc brakes are usually adopted for aircraft, but frequent maintenance are required due to wear of brake-pads. The wear debris also give negative impact on the environment. There is a growing demand for practical use of non-contact type brake mechanisms for aircraft. In this study, the authors focused on eddy current brakes (retarders) used in large vehicles and examined the possibility to apply them to aircrafts. Braking characteristics of the eddy current brake at the landing speed range of an aircraft were investigated by experiments and finite element method. According to the investigation, braking torque goes up by increasing speed but goes down in high speed range. Some results suggested that magnetic flux bias in the conductor disk may be involved in the reduction of braking torque. In this report, the magnetic flux bias is tried to be controlled by taking the following two methods: (1) configuration of three magnets with different strength which gives spatial bias in the magnetic force, and (2) a structure of conductor in which the conductor is divided into two parts and thin permanent magnet is inserted.