This paper intends to clarify the experimental and theoretical characteristics of a swing journal bearing at the small end of the connecting rod in reciprocating compressors and further to clarify the difference in lubricating characteristics between a combination of HFC-134a/ester oil and that of CFC-12/mineral oil. In order to observe the metallic contact states at the bearing under both stable and transient operating conditions, electrodes were mounted on the sliding surface at the bearing and variations of the contact resistance were measured. Then these experimental results were compared with the theoretical results calculated using the lubricating theory based on the Reynolds equation.As a result, we found that the bearing at the small end was in a severe lubricating condition, which partial metallic contact occurred. And there existed a correlation between the metallic contact ratio and the bearing modulus. These experimental results of metallic contact variations agreed qualitatively with the theoretical results of oil film changes. We also noticed that there was no significant difference in lubricating characteristics between a combination of HFC-134a/ester oil and that of CFC-12/mineral oil, and the lubricating condition under the transient operating condition of the refrigerator continued to be severer than that under stable conditions for a long period of time.
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