A hybrid roller bearing having an inner raceway and an outer raceway and a plurality of rollers arranged therebetween. The inner raceway and the outer raceway are made from bearing steel and have a first surface RMS roughness R.sub.q1. At least one roller is made from a ceramic material and has at least at the roller raceway a second surface RMS roughness R.sub.q2. The roughness of the raceways R.sub.q1 is 1.2 to 4 times higher than the roughness R.sub.q2 of the at least one roller, as well as a refrigerant compressor with such a hybrid roller bearing.

A centrifugal compressor for compressing a refrigerant vapour in a refrigeration cycle. The compressor comprises an impeller drive shaft supported by first and second radial bearings for rotation within the compressor housing and an impeller assembly including at least one centrifugal impeller wheel mounted on the impeller drive shaft to rotate with the impeller drive shaft. The first and second radial bearings are hydrodynamic fluid bearings in which the bearing fluid is the refrigerant vapour. The compressor further comprises a conduit for supplying a portion of the refrigerant vapour from the impeller assembly to the first and second fluid bearings.

The invention relates to a lubricated rolling bearing for blade roots including a coating made of a chemical compound of lamellar structure.

A centrifugal compressor for compressing a refrigerant vapor in a refrigeration cycle. The compressor comprises an impeller drive shaft supported by first and second radial bearings for rotation within the compressor housing and an impeller assembly including at least one centrifugal impeller wheel mounted on the impeller drive shaft to rotate with the impeller drive shaft. The first and second radial bearings are hydrodynamic fluid bearings in which the bearing fluid is the refrigerant vapor. The compressor further comprises a conduit for supplying a portion of the refrigerant vapor from the impeller assembly to the first and second fluid bearings.

A centrifugal compressor includes a casing, an impeller, a motor, a diffuser, a magnetic bearing, and a magnetic bearing backup system including at least one dynamic gas bearing and at least one hydrostatic gas bearing. The impeller is attached to a shaft rotatable about a rotation axis. The motor is configured and arranged to rotate the shaft in order to rotate the impeller. The magnetic bearing rotatably supports the shaft. The magnetic bearing backup system is configured and arranged to support the shaft when the magnetic bearing stops operating. The at least one dynamic gas bearing and the at least one hydrostatic gas bearing of the magnetic bearing backup system are disposed radially inwardly relative to the magnetic bearing.

A centrifugal compressor for compressing a refrigerant vapour in a refrigeration cycle. The compressor comprises an impeller drive shaft supported by first and second radial bearings for rotation within the compressor housing and an impeller assembly including at least one centrifugal impeller wheel mounted on the impeller drive shaft to rotate with the impeller drive shaft. The first and second radial bearings are hydrodynamic fluid bearings in which the bearing fluid is the refrigerant vapour. The compressor further comprises a conduit for supplying a portion of the refrigerant vapour from the impeller assembly to the first and second fluid bearings.

The invention relates to a lubricated rolling bearing for blade roots including a coating made of a chemical compound of lamellar structure.

A centrifugal compressor for compressing a refrigerant vapor in a refrigeration cycle. The compressor comprises an impeller drive shaft (28) supported by first and second radial bearings (32) for rotation within the compressor housing and an impeller assembly including at least one centrifugal impeller wheel mounted on the impeller drive shaft to rotate with the impeller drive shaft. The first and second radial bearings are hydrodynamic fluid bearings in which the bearing fluid is the refrigerant vapor. The compressor further comprising a conduit (36) for supplying a portion of the refrigerant vapor from the impeller assembly to the first and second fluid bearings.