SITIS Archives - Topic Details
Program:  SBIR
Topic Num:  OSD10-EP8 (OSD)
Title:  Magnetic Gears and Couplings
Research & Technical Areas:  Ground/Sea Vehicles

Acquisition Program:  
  Objective:  The objective of this topic is to conceptualize, develop, design, prototype and evaluate a quiet, maintenance-free, high torque density magnetic gear and coupling for Navy, DoD, and industrial applications. Mechanical gears require lubrication and maintenance. Magnetic gearing has the potential to be maintenance-free. This alone is reason to pursue development of magnetic gearing for propulsion, power generation, and actuation.
  Description:  The transition to all-electric combatant ships requires S&T investments in many areas. No Navy or DoD investment has been made in the development of magnetic gearing technology. Early academic/industrial attempts at magnetic gearing involved topologies and materials incapable of providing high-torque levels needed in many industrial applications. With the availability of high-temperature permanent magnet materials and, more recently, soft-magnetic composite materials, there is reason to consider the ability of magnetic gears to offer an alternative to mechanical gears and couplings in some navy applications. With modern magnetics software, multiple topologies can be analyzed quickly enabling near optimal configurations for a given application. Potential benefits of magnetic gears over mechanical gears involve inherent overload protection through torque shear, elimination of wear surfaces, elimination of the need for grease and lubricants, long-life, high efficiency, and reduced acoustic noise. The potential for low noise alone is an area of interest for the navy’s combatant fleet, including UXVs. Actuator motors for control surfaces, in particular, may benefit from this technology. Similar benefits could be applied toward some propulsion and generator drives. The referenced literature suggests that magnetic gearing R&D has been limited over the past 30 years, but there has been progress in improving efficiency and torque density. Noise performance has not been evaluated. Previous work has been primarily accomplished in Japan, Denmark (University College of Aarhus and Aalborg University), and the UK (Sheffield Univ.), though there is some emerging academic interest in the US. As for technology pull, the NGIPS roadmap and the Navy’s UUV Master Plan both call for reduced ship signatures, a potential capability offered by this topic. Some of the key objectives of the NGIPS roadmap relative to this SBIR topic are: • Increased technology readiness levels • Decreased system cost / life cycle cost • Improved reliability / survivability / continuity of service • Reduced signature for improved “Stealth”

  PHASE I: Conduct a scientific study of multiple magnetic gearing and coupling concepts, and identify those most likely to add value to Navy applications. The study shall include predictive performance data in the areas of torque capability, torque density, potential for maintenance-free operation, size, weight, cost, magnetic materials & topology, thermal analysis, etc. Preliminary designs for a magnetic gear and magnetic coupling shall be developed. A final report shall detailing the phase I effort shall be provided.
  PHASE II: Based on preliminary designs from phase I, additional analyses / modeling shall be conducted to develop detailed designs for a magnetic gear and a magnetic coupling. Both devices shall be fabricated and performance shall be characterized in the areas of torque capability, torque density (N-m/L, and N-m/kg), efficiency, torque ripple, noise, and overall size and weight at a minimum. In addition to design, development, and testing in this phase, a business case analysis shall be prepared. This BCA shall address life-cycle cost implications of implementing magnetic gears and couplings on existing ships, and on future ships. A final report shall detailing the phase II effort shall be provided.

  PHASE III: This effort will result in a magnetic gear and a magnetic coupling at a Technology Readiness Level (TRL) of 6 by 2013. This fits well with the Next Generation Integrated Power System (NGIPS) Technology Development Roadmap. NGIPS incorporates a "Deadline B - 2014", the date when TRL 6 technologies are needed to support forward fit of technology into submarines and potentially later, 2nd generation CG(X). A follow-on opportunity for transition is "Deadline C - 2018", the date when TRL 6 technologies are needed to support new design amphibious warfare ships, auxiliary ships, DDG(X) and a future new design SSN. The SBIR products (magnetic gear and magnetic coupling) also may lend themselves to transition/implementation on-board existing Navy ships. This decision would depend, in part, on the results of the phase II business case analysis because the up-front cost of retrofitting would need to be considered. PRIVATE SECTOR COMMERCIAL POTENTIAL/

  DUAL-USE APPLICATIONS: The industries that may benefit are those currently employing mechanical gearing and couplings for long-term commercial use. Examples include the electric power industry, commercial ship manufacturing industry, and the aircraft manufacturing industry. The potential for application in the automotive and consumer-centric industries will be influenced less by life-cycle costs than by initial purchase price. The business case analysis conducted in phase II will provide detailed information on the anticipated production costs of the devices. Magnetic transmissions for automobiles and heavy-duty trucks could be an adaptation of this technology in the commercial sector.

  References:   1. NGIPS Technology Development Roadmap, available: 2. Naval S&T Strategy, available: 3. H. Toliyat, Gearing Ratios of a Magnetic Gear for Marine Applications, Proceedings of the IEEE Electric Ship Technologies Symposium, 2009 4. Frank T. Jørgensen, Torben Ole Andersen, and Peter Omand Rasmussen, The cycloid permanent magnetic gear, IEEE Transactions on Industry Applications, vol. 44, No. 6, November/December, 2008 5. K. T. Chau, Dong Zhang, J. Z. Jiang, and Linni Jian, Transient analysis of coaxial magnetic gears using finite element comodeling, Journal of Applied Physics vol. 103, January, 2008 6. S. Mezani, K. Atallah, D. Howe, A high-performance axial-field magnetic gear, Journal of Applied Physics 99, 2006 7. K. Atallah, J. Wang, and D. Howe, A high-performance linear magnetic gear, Journal of Applied Physics 97, 2005 8. Kais Atallah, Stuart D. Calverley, David Howe, High-performance magnetic gears, Journal of Magnetism and Magnetic Materials vols. 272–276 (2004) 1727–1729 9. K. Atallah, D. Howe, A novel high-performance magnetic gear, IEEE Trans. Magn. 37 (2001) 2844. 10. K. Tsurumoto, S. Kikushi, A new magnetic gear using permanent magnet, IEEE Trans. Magn. 23 (1987) 3622. 11. D.E. Hesmondhalgh, D. Tipping, A multielement magnetic gear, IEE PROCEEDINGS, Vol. 127, Pt. B, No. 3, May 1980.

Keywords:  Magnetics, permanent magnet, torque density, gear

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