Design of Integrated Magnetic Springs for Linear Oscillatory Actuators

Spring-assisted oscillating actuators allow the overall energy consumption of a system to be reduced. The concept relies on springs that store and release energy into the system when required. Conventional mechanical springs impose some limitations on a system, mainly in terms of compactness, friction, material fatigue, and failure. Magnetic springs have the potential to overcome these issues, especially for long-stroke high-frequency operation. We report here on the investigation of a magnetic spring into a linear oscillatory motor without any changes to the permanent magnet arrangement on the mover. We focus on a compact and highly integrated design with maximum energy storage capacity. Our analytic equations define the relevant geometrical parameters that exploit the potential of the system best and are on a par with a finite-element-based optimization. We also investigated the expected losses and demonstrate the importance of correct choice of materials to efficient operation. We validated our results using measurements from a prototype linear oscillatory motor featuring the proposed integrated magnetic spring.