Hydraulic multicellular sealing device for centrifugal pumps

Claim 2

A sealing device of the centrifugal multicellular type for preventing any leakage of fluid around a vertical rotatable shaft where it passes through a wall by which two spaces at different pressures are separated, which device comprises: a first stationary annular chamber coaxial with said shaft, which chamber in vertical radial cross-section has the shape of a C with the C opening directed toward the shaft; a second annular chamber within the first one and coaxial with said shaft which chamber has also the shape of a C in vertical radial cross section with the C opening directed toward said shaft the openings of the two chambers being made to coincide at least partially, said second chamber being surrounded by the first chamber and rot-atably mounted with respect thereto and coupled to a motor for being rotated thereby; a hub tightly mounted on a shaft and provided with a series of circular fins vertically spaced which project outward from the shaft and pass through said two corresponding openings of said chambers into the inside of the said second chamber to nearly touch the wall thereof opposite to the chamber opening; said second chamber being provided on its surface facing outward with respect to said shaft with a series of vertically spaced circular fins which project outwards to nearly touch the inner surface of the outer wall of the first chamber; said chambers being partially filled with sealing fluid; one of the two spaces which are separated by said wall through which said shaft passes being open into the space underlying the lowest fin in both chambers while the other space communicates with the space within both said chambers above the highest of the respective fins.

Claim 3

A sealing device of the centrifugal multicellular type for preventing any leakage of fluid around a vertical rotatable shaft where it passes through a wall by which an upper space at lower pressure is separated from a lower space of higher pressure which device comprises: a stationary annular chamber coaxial with said shaft and having cylindrical vertical walls and horizontal top and bottom walls; an annular drum with cylindrical vertical walls and horizontal top and bottom walls the inner diameter of said drum being greater than said chamber inner diameter and the outer diameter being smaller than said chamber outer diameter; said drum being enclosed within said casing and coaxial therewith; which drum on its outer vertical surface is provided with a series of vertically spaced circular fins which project outwards to nearly touch the vertical outer wall of said chamber; said drum being rotatably mounted with respect to said shaft and said chamber and coupled with a motor for being rotated thereby; a hub tightly mounTed around said shaft and provided at its outer surface with a series of vertically spaced circular fins which project into said drum to nearly touch the outer vertical wall thereof, a circular horizontal window being provided through said casing and through said drum at a distance from the respective bottoms for permitting said fins to enter said drum; said fins of each series being all flat and horizontal except for the lowest one which is bent downward from said drum and said hub to form a downwardly open conical bell; the lowest one of said spaces to be sealed one from the other being in communication with the spaces in said drum and in said chamber underlying the lowest fin respectively while the upper space is made to communicate with the spaces in said drum and chamber overlying the highest fin respectively said chamber and drum being partially filled with sealing fluid.

Claim 4

A sealing device of the centrifugal multicellular type for preventing any leakage of fluid around a vertical rotatable shaft where it passes through a wall by which an upper space at lower pressure is separated from a lower space of higher pressure which device comprises: a stationary annular chamber coaxial with said shaft and having cylindrical vertical walls and horizontal top and bottom walls; an annular drum with cylindrical vertical walls and horizontal top and bottom walls the inner diameter of said drum being greater than said chamber inner diameter and the outer diameter being smaller than said chamber outer diameter; said drum being enclosed within said casing and coaxial therewith; which drum on its outer vertical surface is provided with a series of vertically spaced circular fins which project outwards to nearly touch the vertical outer wall of said chamber; said drum being rotatably mounted with respect to said shaft and said chamber and coupled with a motor for being rotated thereby; a hub tightly mounTed around said shaft and provided at its outer surface with a series of vertically spaced circular fins which project into said drum to nearly touch the outer vertical wall thereof, a circular horizontal window being provided through said casing and through said drum at a distance from the respective bottoms for permitting said fins to enter said drum; said fins of each series being all flat and horizontal except for the lowest one which is bent downward from said drum and said hub to form a downwardly open conical bell; the lowest one of said spaces to be sealed one from the other being in communication with the spaces in said drum and in said chamber underlying the lowest fin respectively while the upper space is made to communicate with the spaces in said drum and chamber overlying the highest fin respectively said chamber and drum being partially filled with sealing fluid.

Claim 5

A sealing device as per claim 2 wherein the motor which rotates said drum comprises an annular electric rotor attached to said drum which rotor is mounted around said shaft by means of roller bearings and an annular stator around said rotor which stator is mounted within a bell-shaped housing mounted on top of said chamber and provided with a central bore for said shaft; a further roller bearing coplanar with the first one being inserted between an annular extension of said stator and a circular rib integral with said bell-shaped housing; said rotor being connected to said drum by means of a cylindrical sleeve coaxial with said shaft which sleeve extends downwardly from said stator into said chamber through an annular opening of which the top wall of the chamber is provided; two roller bearings being inserted between said sleeve and said shaft.

Claim 6

A sealing device as described in claim 2 wherein the top wall of said drum is provided with a first range of through holes spaced along a circle coaxial with said shaft for inletting the sealing fluid thereinto from a reservoir through a first pipe the outlet of which is at a distance from said shaft less than said range of holes and less than a circular baffle of which said top wall is provided for preventing said fluid from being centrifuged away from said holes; with a second range of through holes regularly spaced along a circle coaxial with said shaft at a distance therefrom greater than said first range and said baffle; with a second pipe which connects the inside of said chamber at a position thereof closer to said shaft than the outer wall of said chamber with the top of the sealing fluid reservoir, whereby the sealing fluid introduced into the drum is centrifuged in operation against the outer wall of the drum to form a layer of which the radial thickness is equal to the distance between the latter wall and said row of holes while the fluid exceeding said layer is discharged through the latter holes into said chamber wherein is centrifuged - when the said drum rotates - against the outer wall of said chamber to form a layer of which the radial thickness is equal to the distance between the last recited wall and the open end of said second pipe while the fluid exceeding said layer is returned to said reservoir through said second pipe.

Claim 7

A sealing device as described in claim 4 which device is further provided with a filling system of the sealing fluid reservoir for keeping it at a constant level which system comprises a sealed receptacle provided with a filling valve on top of it and with a pipe at its bottom which terminates with an open end into said reservoir at the same level to be attained by the sealing fluid therein; which pipe is provided with a valve to be closed when said receptacle is to be refilled through said filling valve.

Claim 8

In a motor driven centrifugal pump provided with an impeller and a shaft for connecting said impeller to said motor a sealing device as claimed in claim 1 provided about said shaft.