Centrifugal pump bearing arrangement

Claim 1

Centrifugal pump of the sealless type comprising: a housing containing a pumping chamber, a pump inlet passage extending from an inlet in the housing and opening into the pumping chamber and a pump outlet passage running from the pumping chamber to an outlet in the housing; a shaft mounted in said housing for rotation; a pump impeller attached to the forward end of the shaft for rotation with the shaft in the pumping chamber and a magnet holder attached to the rear end of the shaft carrying a first magnetic means adapted to be magnetically coupled to a second magnetic means rotated by a rotary driving device such as an electric motor, said shaft being mounted in at least two bearings spaced from each other along the length of the shaft and located between the impeller and the magnet holder, a shell surrounding the shaft bearings, and magnet holder to seal the pump from the exterior and prevent the pumped fluid from leaking, said shell being located between the two magnetic means and being able to transmit magnetic forces between the two magnetic means for magnetically coupling said two magnetic means together, said housing containing a passage for conducting lubricating fluid to the part of the shaft located rearward of the bearings relative to the impeller and forward of the magnet holder, and means for feeding the lubricating fluid forwardly along the length of said shaft through both bearings before exiting from the bearings adjacent the impeller whereby the pressure on the lubricating fluid is automatically lowered by passage through the bearings causing it to be at a substantially reduced pressure when exiting from the bearings adjacent the impeller, thereby reducing the pressure of said lubricating fluid applied to the impeller as it exits from said bearings.