Estimation of coefficient boundary friction under mixed lubrication in refrigerant mixed lubrication in refrigerant atmosphere

摘要

A Falex block on ring-type test machine that is capable of performing friction tests under lubrication in refrigerant atmosphere is manufactured with the purpose of determining the boundary friction coefficient of sliding parts in refrigerant compressors under the mixed lubrication condition. Attempts were made to estimate the boundary friction coefficient by measuring friction characteristics, sliding component materials, and lubricants and by comparing these with the analysis of mixed lubrication conditions presented earlier. The obtained results showed that the boundary friction coefficient under the mixed lubrication condition, estimated by comparing experimental results with those obtained by the analysis of mixed lubrication, either coincided with the coefficient of friction in the boundary lubrication region or is lower. The application of the present technique allowed more accurate evaluation of lubrication properties of lubricants and friction materials of real machines that operate mainly under the mixed lubrication conditions and showed the possibility of evaluating the surface roughness simultaneously. It is found that the effect of the difference in composition of HFC refrigerants on the frictional characteristics is rather weak.