An Anti-Fall Device of Construction Hoist Based on PM-ECB

Permanent magnet eddy current braking (PM-ECB) is a new type of non-friction braking technology. It uses the magnetic field generated by the permanent magnet to produce eddy current loss in the process of relative motion for braking. It does not need external excitation power supply. It has the advantages of compact structure, high reliability, no noise, no contact and so on. Based on the electromagnetic theory, the basic principle of permanent magnet eddy current brake is analyzed, and the calculation formula of eddy current brake force of annular magnet moving along the conductor tube is given; At the same time, combined with the specific construction elevator, the dynamic model of permanent magnet eddy current brake for cage falling without initial speed is established, and the influence of magnet array arrangement on magnetic flux density and the influence of air gap between magnet group and conductor tube on cage falling speed are studied. The simulation results show that the magnet group can achieve the braking effect when the load falls without initial speed or overload at rated speed, which provides the basis for the design of permanent magnet eddy current anti falling device of construction hoist.