Principle and application of new magnetic force control method using a composite element of two active materials

摘要

A new type of magnetic force control technique using a magnetostrictive element is proposed. This is based on the inverse magnetostrictive effect of giant magnetostrictive element and realized by composing a closed parallel magnetic circuit with a permanent magnet in magnetic yoke. The magnetic force between the yoke and armature can be adjusted by controlling the stress in the magnetostrictive element. In this paper, the feasibility of the technique is examined by a simple experimental system. For the purpose of controlling the strain in the magnetostrictive element efficiently, a composite element is proposed, in which two active materials, the magnetostrictive ring and the piezoelectric ring actuator are mechanically coupled via strain. This implies that the magnetization in the magnetostrictive ring can be controlled by adjusting the voltage of the piezoelectric actuator. The mechanical structure of the element is designed and found to work efficiently. Since the magnetic field in this composite element is controlled by voltage instead of current, it is effective in saving energy and avoiding heat generation.