Traditionally, scroll compressors are mainly made of metallic parts and oil is used to lubricate the friction surfaces and reduce discharge temperature and leakage. But for the food processing, medical systems, textile manufacturing, fuel cell system, and other super-clean fields, the oil-less operation is critical. The oil is strictly forbidden in the working chambers of the scroll compressor in order to get the oil-free compressed air. So it is very important to develop the oil-free scroll compressor (OFSC). In this paper, the working principle and structure characteristics of the OFSC are investigated. Some of research works and the recent patents in this area are described and analyzed in detail, especially the water injection and air cooling OFSC. The future development on an OFSC is also presented. The analysis results demonstrated that there is dramatic growth potential in OFSC field.
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