Patent ID: 6176092
Filing Date: 2001-01-23
Classification: F04D,F05D,F16C,F25B,H02K,Y10S

Abstract:
A centrifugal liquid chiller comprising:a condenser, said condenser condensing refrigerant gas to the liquid state when said chiller is in operation;a metering device, said metering device receiving refrigerant from said condenser and reducing the pressure thereof;an evaporator, said evaporator receiving refrigerant from said metering device and causing liquid refrigerant to evaporate when said chiller is in operation;a compressor, said compressor receiving refrigerant from said evaporator and delivering refrigerant in the gaseous state to said condenser when said chiller is in operation, said compressor having a shaft, at least one impeller being mounted on said shaft, said shaft being rotatably supported by at least one bearing, said at least one bearing being a rolling element bearing, the rolling elements of said bearing being fabricated from a ceramic material, said at least one bearing being lubricated by refrigerant and in the absence of oil, refrigerant delivered to said at least one bearing for lubrication purposes being at least primarily in the liquid state and a portion of the refrigerant used in the lubrication of said at least one bearing being permitted to vaporize at the location of said at least one bearing as a result of the bearing lubrication process; anda reservoir from which liquid refrigerant is supplied to said at least one bearing for bearing lubrication purposes and which is discrete from said evaporator and said condenser, said reservoir containing refrigerant in the liquid state both during chiller operation and for a period of time subsequent to shutdown of said chiller, the amount of such liquid refrigerant in said reservoir being sufficient to ensure the delivery of adequate liquid refrigerant, for lubrication purposes, to said at least one bearing both while said chiller is in operation and while said shaft on which said at least one impeller is mounted coasts to a stop after said chiller is shutdown.