A Study on Contact Voltage Waveform and Its Relation with Deterioration Process of AgPd Brush and Au-Plated Slip-Ring System with Lubricant

Koichiro SAWA  Yoshitada WATANABE  Takahiro UENO  Hirotasu MASUBUCHI  

IEICE TRANSACTIONS on Electronics   Vol.E103-C   No.12   pp.705-712
Publication Date: 2020/12/01
Publicized: 2020/06/08
Online ISSN: 1745-1353
DOI: 10.1587/transele.2020EMP0002
Type of Manuscript: Special Section PAPER (Special Issue on Recent Development of Electro-Mechanical Devices)
slip ring,  Au plating,  lubricant,  contact voltage waveform,  fluctuation,  tunnel effect,  rotation speed,  

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The authors have been investigating the deterioration process of Au-plated slip-ring and Ag-Pd brush system with lubricant to realize stable and long lifetime. Through the past tests, it can be made clear that lubricant is very important for long lifetime, and a simple model of the deterioration process was proposed. However, it is still an issue how the lubricant is deteriorated and also what the relation between lubricant deterioration and contact voltage behavior is. In this paper, the contact voltage waveforms were regularly recorded during the test, and analyzed to obtain the time change of peak voltage and standard deviation during one rotation. Based on these results, it is discussed what happens at the interface between ring and brush with the lubricant. And the following results are made clear. The fluctuation of voltage waveforms, especially peaks of pulse-like fluctuation more easily occurs for minus rings than for plus rings. Further, peak values of the pulse-like fluctuation rapidly decreases and disappear at lower rotation speed as mentioned in the previous works. In addition, each peaks of the pulse-like fluctuation is identified at each position of the ring periphery. From these results, it can be assumed that lubricant film exists between brush and ring surface and electric conduction is realized by tunnel effect. In other words, it can be made clear that the fluctuation would be caused by the lubricant layer, not only by the ring surface. Finally, an electric conduction model is proposed and the above results can be explained by this model.