bell-mouth geometry, journal bearing, anti-seizure properties, frictional resistance, reciprocating compressor
The present study describes the applicability of a bell-mouth geometry to the improvement of the tribological properties of journal bearings of reciprocating compressors for home appliance products such as refrigerators. A roller burnishing process was used to apply the bell-mouth geometry to the edge of cast iron journal bearings. The resulting geometry of the edge consisted of a micro-scale gradient of 1/1000 and a length of 4-6 mm. The tribological properties were evaluated at a constant sliding speed under lubricated conditions, using a specially-developed testing apparatus which simulated the contact behavior of the shaft and bearing in an actual reciprocating compressor. The applied load was increased incrementally in order to evaluate the occurrence of seizure. The specimens were prepared so that the material, surface roughness, accuracy, and clearance were the same as the shaft and bearing in an actual reciprocating compressor. Significant improvement of anti-seizure properties and a decrease in frictional resistance were found with the bell-mouth bearings. Furthermore, the reliability of journal bearings was evaluated using reciprocating compressors with bell-mouth bearings. Significant increase of COP (coefficient of performance) and improvement of anti-wear properties at both edge of the bell-mouth bearing was found. It was therefore concluded that the application of the bell-mouth geometry was effective for improving the tribological properties of journal bearings, and it was found that bell-mouth geometry is also applicable for reciprocating compressors.