US 6,558,139 B2 · Bearings with hardened rolling elements and polymeric cages for use submerged in very low temperature fluids

Abstract

A self lubricating bearing for use submerged in cryogenic fluids. The self-lubricating bearing comprises hardened races, hardened rolling elements and polymeric retainers or cages. More particularly, the rolling elements may be hardened balls, and the polymeric cages may include PEEK. In particular a bearing for self lubricated use in seal-less, magnetic drive pump for pumping fluids at very low temperatures and cryogenic temperatures below about −100 degrees centigrade such as liquid nitrogen and temperatures below about −150 degrees centigrade such as liquefied natural gas (LNG). An environment for submerged use of such a bearing may be a magnetically driven cryogenic pump with a housing having an intake and exhaust with a back plate mounted therein in which a shaft is journaled in self-lubricating bearings having hardened stainless steel or ceramic balls, stainless steel races and polymeric retainers or cages for retaining the balls for rolling contact in the races. An impeller is mounted on the first end and a first magnet is mounted on the second end of the shaft.

Claims20

Dependent claims

A magnetic drive pump for use in pumping a very low temperature fluid at less than about −100 degrees centigrade comprising:

a back plate having a rotatable shaft journaled therein said rotatable shaft having a first end and a second end journaled in a bearing comprised of a hardened race in said back plate, a plurality of ceramic rolling elements in said race, and a retainer comprised of a polymeric material holding said rolling element is spaced apart position about said race;
an impeller mounted to a first end of said rotatable shaft;
a first magnet comprising a first material having coefficient of thermal expansion mounted to a second end of said rotatable shaft and contained within a casing mounted to said rotatable shaft, said casing comprising a material having a second coefficient of thermal expansion greater than the first coefficient of thermal expansion of the material comprising said magnet;
said back plate being mounted within a housing having openings formed therein for intake and exhaust of a fluid to be pumped at very low temperature;
and
a second magnet positioned in close proximity to said housing for rotation therearound and adapted for mounting to the shaft of a motor for rotating said first magnet in the housing.

3 more elements

Dependencies are inferred from the claim text.

Bearings with hardened rolling elements and polymeric cages for use submerged in very low temperature fluids

Life of this patent

Bearings with hardened rolling elements and polymeric cages for use submerged in very low temperature fluids

Life of this patent

Abstract

Claims20