Daido Steel Co., Ltd. and Honda Motor Co., Ltd. became the world’s first companies to achieve practical application of a hot deformed neodymium magnet containing no heavy rare earth and yet with high heat resistance properties and high magnetic performance required for the use in the driving motor of a hybrid vehicle. This heavy rare earth-free hot deformed neodymium magnet will be applied first to the all-new Honda FREED, scheduled to go on sale this fall.
Neodymium magnets have the highest magnetic force among all magnets in the world and are being used for the drive motors of electric vehicles including hybrid vehicles, and therefore demand for neodymium magnets are expected to grow exponentially in the future.
For use in the drive motors of electric vehicles, neodymium magnets must have high heat resistance properties as they are used in a high-temperature environment. Adding heavy rare earth (dysprosium and/or terbium) to the neodymium magnets has been a conventional method to secure such high heat resistance.
However, major deposits of heavy rare earth elements are unevenly around the world, and also are categorized as rare metals; thus, the use of heavy rare earth carries risks from the perspectives of stable procurement and material costs. Therefore, a reduction in the use of heavy rare earth elements has been one of the major challenges needing to be addressed in order to use neodymium magnets for the drive motors of hybrid vehicles.
Honda designed a new motor which accommodates this new magnet. In addition to the shape of the magnet, Honda revised the shape of the rotor to optimize the flow of the magnetic flux of the magnet. As a result, the hot deformed neodymium magnet that contains absolutely no heavy rare earth became usable for the drive motor of a hybrid vehicle, demonstrating torque, output and heat resistance performance equivalent to those of a motor that uses the conventional type of magnet.
Adoption of this technology enables a break from the constraints associated with heavy rare earth, which had been one of the challenges to expanding the use of neodymium magnets. This technology will make it possible to avoid resource-related risks and diversify channels of procurement.
Honda will first apply this hot deformed neodymium magnet with absolutely no heavy rare earth to the Honda SPORT HYBRID i-DCD, a hybrid system Honda will adopt for the all-new FREED scheduled to go on sale this fall. Honda will continue expanding the application of this technology to new models in the future.
