Friction reducing arrangement for hydraulic machines

Claim 1

A pump assembly comprising: a housing having a vertical axis and including a central inlet passage generally concentric with said axis, an outlet passage radially disposed with respect to said housing axis, and a fluid chamber formed therebetween, said chamber having spaced upper and lower radially extending surfaces; a conduit extending through an upper portion of said housing and communicating with said fluid chamber; a shaft positioned within said conduit and being generally concentric with said housing axis, an end portion of said shaft being positioned within said fluid chamber; a rotor rotationally supported by said end portion of said shaft and concentrically mounted in said fluid chamber, said rotor having a rotational axis substantially coincident with said housing axis and at least one fluid passageway extending through said rotor for forming a fluid flow path between said inlet and outlet passages, said rotor further having upper and lower surfaces; upper and lower annular spaces respectively defined between said upper and lower surfaces of said rotor and said upper and lower surfaces of said chamber, said upper and lower annular spaces include upper cavity regions radially adjacent said housing axis and lower cavity regions extending radially therefrom, said lower cavity regions of said annular spaces being bounded by clearance gaps defined by circumferential edges of said rotor and respective portions of said upper and lower surfaces of said housing, and said upper and lower annular spaces being declined radially from said housing axis; seal means interposed between said rotor and said housing in said upper cavity region of said upper and lower annular spaces, said seal means in said lower annular space being adapted to maintain a pressure differential between said inlet passage and said lower annular space; peripheral sealing means formed at said clearance gaps for limiting the flow of pumped fluid into and out of said upper and lower annular spaces through said clearance gaps; a fluid supply port in each said upper cavity region of said upper and lower annular spaces; and means supplying pressurized fluid through said supply ports to said annular spaces for decreasing the level of pumped fluid in said annular spaces as the pressure of the pressurized fluid is increased relative to the pressure of the pumped fluid and for increasing the level of pumped fluid in said annular spaces as the pressure of the pressurized fluid is decreased relative to the pressure of the pumped fluid, said annular cavities forming bubble chambers entrapping the pressurized fluid therein with the sole means for escape of pressurized fluid and pumped fluid being through said clearance gaps in said lower cavity regions of said upper and lower annular spaces.