Centrifugal pump for cryogenic pumped media

A rotary direct-drive single-stage or multi-stage centrifugal pump for a cryogenic medium, having a pump housing for the pump and an electric drive motor unit serving as a pump drive in a motor housing,

• wherein a shaft of the drive motor unit is mounted on two roller bearings and
• wherein a first roller bearing of said two roller bearings is an initially unlubricated roller bearing that is configured for lubrication during operation of the centrifugal pump by the cryogenic medium,
• and further wherein the first roller bearing is on a pump housing side and located nearer to the pump housing compared to a second roller bearing on a drive motor side of said two roller bearings,
• characterized in that
• a first communicating connection is configured between a pressure side in the pump housing and the first roller bearing on the pump housing side, for a diverted part of a main conveying flow of the cryogenic medium to the first roller bearing, and
• a second communicating connection is configured between the first roller bearing on the pump housing side and a suction side for the diverted part of the main conveying flow of the cryogenic medium back to the suction side and into the main conveying flow of the cryogenic medium,
• wherein a circulation of the diverted part of the cryogenic pumped medium is ensured between the pressure side in the pump housing and only the first roller bearing on the pump housing side,
• wherein a housing cover is located between the motor housing and the pump housing, and the housing cover has a connecting channel in the shape of a bore between the pressure side in the pump housing and the first roller bearing on the pump housing side to form the first communicating connection, and
• wherein the housing cover and the shaft are sealingly engaged to achieve a barrier between the pump housing and the motor housing.