Portland State University

Jonathan Bird

Various examples of a variable stiffness magnetic spring with a linear stroke length are provided. The stiffness of the magnetic springs is varied through rotation of one or more magnets, and both positive and negative spring constants are achievable. In one example, a variable stiffness magnetic spring includes a first magnetic component and a second magnetic component, wherein the first magnetic component is coaxial with the second magnetic component, the first magnetic component is rotatable about an axis and relative to the second magnetic component to adjust a stiffness of the variable stiffness magnetic spring, and the second magnetic component is translatable along the axis and relative to the first magnetic component. While such variable stiffness magnetic springs exhibit highly linear stroke lengths, such variable stiffness magnetic springs can be positioned in series to achieve an even longer linear stroke length.

Rotary and linear adjustable stiffness magnetic springs

The disclosure presents configurations and analyses of magnetic gears, which may be used in the second stage of a multistage magnetically geared generator for a marine hydrokinetic generator application and/or other applications as described. In order to reduce field harmonics and maximize the torque density, a Halbach rotor topology is utilized. One feature of the disclosed configuration is a unique magnet arrangement that enables inner and outer Halbach rotor magnets to be more easily assembled, even with dimensional tolerance inaccuracies. The disclosed Halbach magnet rotor topology makes use of the internal magnet forces to retain the magnets in position, and the disclosed configuration also helps with the assembly process.

Electromagnetic configurations and assembly methods for a Halbach rotor magnetic gear

This disclosure presents a new type of variable stiffness magnetic spring, which can have a highly linear translational force characteristic. The variable stiffness is achieved through the rotation of a central magnet. Both positive and negative spring constants can be created. Using an analytic-based field analysis modelling technique, the operating principle and linearity characteristics of the adjustable magnetic spring are studied. The use of a magnetic spring with an adjustable negative spring constant could enable an ocean generator to continuously operate in a resonant state, thereby greatly increasing its power generation capability. The described variable stiffness spring could also be useful in other energy harvesting applications, robotic actuator applications, and/or other applications.

Variable stiffness magnetic spring

This application relates to translating mechanical energy from a low-speed rotor to a high-speed rotor or vice versa in a magnetic gearbox. More specifically, this application discloses various embodiments of a coaxial magnetic gearbox with flux concentration Halbach rotors. In certain implementations, the device further comprises a circular back iron (or other ferromagnetic material) disposed concentrically along the axis of the cylindrical magnetic gearing device. In such embodiments, this flux concentration back iron (or ferromagnetic pole) improves the torque density and can also help retain the magnets in place.

Growing community of inventors

Portland, OR, United States of America

Jonathan Bird