|Title:||Methods for Detection of Lubrication Failure Applied to a Swashplate Compressor
|Author(s):||Drozdek, J.C.; Chappell, J.D.; Cusano, C.; Hrnjak, P.S.; Miller, N.R.; Newell, T.A.
|Subject(s):||mobile air conditioning systems
|Abstract:||Understanding lubrication failures at the shoe/swash plate contact of automotive swash plate compressors
will greatly enhance the reliability of the air conditioning system. Maintaining proper lubrication is not
always possible during transient conditions. Therefore, a method for detection of lubricant loss is of great
interest to the automotive industry. Three methods for detecting lubrication loss were examined: contact
resistance, acoustic emission, and dynamic pressure oscillations.
A mobile air conditioning test stand capable of recording many system parameters was used. Oil return
to the compressor was monitored using an oil separator and a refrigerant/oil concentration sensor. Data
were taken during steady oil return rates and after oil shut off.
The electrical contact resistance between the shoe and swashplate was used to indicate changes in the
lubrication conditions at this critical interface. Measurements were taken at two oil return rates, during
steady oil return tests. Preliminary results show that the minimum contact resistance is independent of
the steady oil flow rates tested.
In addition to the contact resistance, an acoustic emission (AE) sensor and a dynamic pressure
transducer (DPX) were used to monitor oil film breakdown after oil shut off. Preliminary data indicate that
the DPX may be an early indicator of low oil circulation. Even after several hours of operation after oil
shut off, the magnitude of the contact resistance indicated no oil film breakdown had occurred. It was
determined that the AE sensor is probably not an adequate indicator of lubrication breakdown.
|Publisher:||Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign.
|Series/Report:||Air Conditioning and Refrigeration Center TR-160
|Sponsor:||Air Conditioning and Refrigeration Project 92
|Date Available in IDEALS:||2009-05-26