Development of Grease Film Breakdown Observing Device

Sunahara, Kenji; Yamashita, Shinji; Yamamoto, Masahiro; Ikeda, Michiaki; Nishikawa, Hiroshi; Matsuda, Kenji; Kaneta, M.

doi:10.2474/trol.3.40

Cited by 5 publications

(3 citation statements)

References 2 publications

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“…A semireflecting chromium (Cr) layer of 20 nm thickness was deposited onto the working surface of the glass disk. In order to reduce the resistance between contacting surfaces, the Cr layer was covered with an indium tin oxide (ITO) film of 300 nm thickness [11,30], thereby reducing the resistance to approximately 13 Ω. The steel ball, which is insulated from its driving shaft by insulating paper, was fastened in position with a plastic bolt.…”

Section: Experimental Apparatusmentioning

confidence: 99%

“…The occurrence of bearing damage induced by electrical currents is denoted as "electric erosion" [7,8]. The adverse effects of electric erosion predominantly manifest as fluting [9,10], frosting, and the formation of electric pitting craters [11]. Concurrently, the generation of bearing current heightens the susceptibility to bearing failure due to white etching crack (WEC) [12].…”

Section: Introductionmentioning

confidence: 99%

“…Bleger et al [19] employed a combined experimental and numerical approach to study discharge behavior in motor bearings. Sunahara et al [11] employed a camera to capture electrical discharge occurring between the ball and the glass disk. They also observed that the threshold value of voltage with oil film breakdown increases with an increase in oil film thickness.…”

Section: Introductionmentioning

confidence: 99%

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Study on Grease Lubrication and Electric Erosion Characteristics in AC Electric Fields

Li,

Guo,

Jing

et al. 2024

Lubricants

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Protecting motor bearings from electric erosion is crucial as electric vehicles evolve. To better understand how lubrication interacts with electric discharge within motor bearings during varying speeds of vehicle operation, an optical ball-on-disk tribometer was modified to investigate the influence of alternating current (AC) electric fields on film thickness, friction force under various lubrication regions, and discharge characteristics. The study revealed that in AC electric fields, as the lubrication state shifts from mixed lubrication to fluid lubrication region, the electrical characteristic of the lubricating oil film changes from resistive to capacitive, accompanied by an increase in discharge frequency. Under the elastohydrodynamic lubrication (EHL) region, an electrical potential difference between the surfaces separated by the lubrication film leads to a reduction in film thickness, which can be attributed to the generation of Joule heating. If the potential difference across the oil film increases to the threshold voltage, destructive discharge occurs with the emission of a significant amount of purple light. Joule heating generated by the AC electric fields also results in a reduction in the friction coefficient under the fluid lubrication region. However, due to the reduction in film thickness, the lubrication state eventually moves to mixed lubrication, leading to a substantial increase in the friction coefficient. In addition, the study also investigated the use of grease with a nanographite conductive additive. It was found that inappropriate additive amounts can lead to discharge phenomena occurring outside the contact region.

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Section: Experimental Apparatusmentioning

confidence: 99%