Development of the Lead-Free Carbon Brush Material for Starters(Automotive Application, <Special Section>IS-EMD2004-Recent Development of Electro-Mechanical Devices)

概要

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Carbon brushes for starters are used under severe conditions of high electric current density, high contact pressure and high sliding velocity. Lead has traditionally been added to carbon brushes to improve their performance and durability. Because lead is an environmentally hazardous substance, after January 2005 the EU will prohibit adding lead to carbon brushes for electric motors installed in vehicles. The purpose of our current study is to develop materials of lead-free carbon brushes for starters. Analyzing the effects of adding lead has shown that lead inhibits the brush resistance from increasing under high temperatures, or a combination of both high temperature and high humidity. This is because corrosion of lead precedes that of copper, which is one of the materials comprising the brush, and this prevents the copper from corroding. Moreover, lead functions as a solid lubricant and reduces brush wear. We developed the lead-free brush material, by adding soft metallic substances that corrode prior to copper and are also oxidation-resistant, as well as possessing low hardness and solid lubricant properties. The developed lead-free brush surpasses the conventional lead-added brush in durability and permanence.
社団法人電子情報通信学会の論文
2005-08-01