Patent ID: 6068455
Filing Date: 2000-05-30
Classification: F04D,F05B

Abstract:
A fluid pumping device comprising:a motor assembly including a rot or and a central shaft, said central shaft having an extended first end, and a second end, said rotor being supported by said central shaft intermediate said first and second ends of said central shaft;a fluid filled motor housing, said central shaft and said rotor being s supported for rotation within said fluid filled motor housing, said extended first end of said central shaft extending out of said fluid filled motor housing;at least one large surface area hydrodynamic journal bearing supporting said central shaft, said large surface area hydrodyamic journal bearing being located intermediate said rotor and said extended first end of said central shaft and providing small radial, fluid receiving gaps between said large surface area hydrodynamic journal bearing and said central shaft;a rotatable pump impeller supported for rotation in a pump housing, said pump impeller being attached to said extended first end of said central shaft, said pump housing receiving a fluid to be pumped, the fluid to be pumped by said pump impeller in said pump ho using being subject to temperature variations;limited fluid access between said fluid filled motor housing and said pump housing, the fluid in said fluid filled motor housing being substantially thermally stagnant and isolated from the fluid in said pump housing by said limited fluid access between said fluid filled motor housing and said pump housing, said limited fluid access restricting flow of the fluid into said fluid filled motor housing to pressurizing and replenishment fluid flow such that the fluid temperature about said rotor and said large surface area hydrodynamic journal bearing is substantially constant at an ambient temperature; anda pump mount intercoupling and spacing apart said pump housing and said fluid filled motor housing by an isolation gap, said pump mount including a sleeve having a low cross-sectional area and low thermal conductivity, said low cross-sectional area and low thermal conductivity sleeve extending between, and thermally separating said fluid filled motor housing and said pump housing, said low cross-sectional area and low thermal conductivity sleeve forming a low thermal conductivity path between said pump housing and said motor housing, said isolation gap spacing said pump housing and said fluid filled motor housing to prevent convective heat transfer between said pump housing and said fluid filled motor housing, said motor assembly rotor and the fluid in said fluid filled motor housing being thermally isolated from the fluid in said pump housing by said limited fluid access between said fluid filled motor housing and said pump housing, by said low cross-sectional area and low thermal conductivity sleeve and by said isolation gap preventing convective heat transfer between said fluid filled motor housing and said pump housing, the fluid in said fluid filled motor housing and said motor assembly rotor remaining thermally isolated from temperature changes in the fluid to be pumped by said pump impeller.