SBIR-STTR Award

The proposed research seeks to develop new constant force brush holders incorporating pseudoelastic alloys for use with advanced metal foil and fiber brushes. The new brush holders satisfy requirements relevant to brush pressure and wear movements; they are also compact, resistant to prevalent operating temperatures and lateral forces, and capable of minimizing electrical losses while transferring high current densities. Incorporaition of pseudoelastic springs is the distinguishing feature of the new holder design. Pseudoelastic alloys can be strained orders of magnitude more than normal spring materials without being plastically deformed; the stress level associated with these large pseudoelastic strains is practically constant. The proposed Phase I research will: (1) select geometric configuraitons, compatible pseudoelastic alloys and detailed deisgns for satisfying the targeted requirements in different circumstances; and (2) manufacture pseudoelastic-based mechanical holders, and verify their performance through simulated laboratory tests. The Phase I Option would quantify the competitive technical and cost advantages of the new brush holders. The proposing group includes a leading manufacturer of brush holders and a major supplier of pseudoelastic alloys.

The Phase I of this project demonstrated the viability of a novel brush holder design which satisfies strict requirements on geometry, electrical losses and current density, and employs a pseudoelastic spring to accommodate relatively large deformations at constant force. The proposed Phase II (and Phase II Option) efforts implement integrated analytical and experimental tasks in order to fully develop and optimize the design and fabrication processes of the pseudoelastic-based brush holder devised in Phase I research. Mechanical and electrical aspects of the brush holder performance as well as its longevity under service conditions will be demonstrated. The following objectives will be achieved in Phase II research: (1) optimize the pseudoelastic spring design and processing condition, and verify its performance under repeated and sustained loads, axial and lateral load combinations, and environmental effects; (2) design and experimentally verify the mechanical and electrical performance of the integrated system of pseudoelastic spring and flexible mechanisms for current transfer through the holder; and (3) design, fabricate and experimentally evaluate the complete holder system comprising the pseudoelastic spring and current transfer mechanism, the housing and support elements, and the insulation and connection mechanisms. The follow-up Phase II Option will accomplish the following objectives: (4) evaluate the perofrmance of brush holders in a motor under actual service conditons; and (5) develop a comprehensive commercialization plan for the technology. The brush holder design and fabrication process will be fully documented, and several holders will be manufactured for independent evaluation.

Benefits:
The new brush holder design enables advanced metal fiber and foil brushes to reach their full potential for enhancing the performance of diverse direct current electric machines, including high-torque electric motors, compact and high-performance DC generators, and high-current/low-voltage electric machines. Fields of application include surface ships and submarines, transportation, paper mills, pulsed electric welding, electroplating, and environmentally attractive low-voltage energy sources based on solar, thermoelectric and fuel cell technologies.

Keywords:
Brush Holders Current Density Electric Machines Electrical Losses Metal Fiber and Foil Brushes Pseudoelastic Springs Sliding Contacts Surface Ships and Submarines