BALL BEARING LUBRICATION IN REFRIGERATION COMPRESSORS

摘要

When the refrigerant R134a is mixed with an ester oil and used in compressor bearing lubrication, no EP action is experienced. The refrigerant contains no chlorine and the lubricant additives can not be chemically active like normal EP additives, not to deposit in and destroy the heat exchangers. The lubricant film thickness thus needs to be considerably larger for an R134a compressor bearing than for e.g. an R22 compressor bearing if the same service life should be expected for the two bearings. Typically 50% higher viscosity was needed for the R134a mixture to get a certain wear rate compared to an R22 mixture giving the same wear rate. To avoid the problem with high wear rate at high refrigerant concentrations and to make it possible to run the compressor bearings with less oil an experimental investigation was performed. The experiments investigated the possibility to locally increase the oil concentration at the elastohydrodynamic contacts in the bearings to get better lubrication.