Rotary kinetic fluid motors or pumps – With control means responsive to non-cyclic condition... – By shaft speed or torque responsive means
Reexamination Certificate
1998-11-16
2001-05-01
Verdier, Christopher (Department: 3745)
Rotary kinetic fluid motors or pumps
With control means responsive to non-cyclic condition...
By shaft speed or torque responsive means
C415S111000, C415S113000, C415S171100, C415S174300, C415S231000, C277S423000, C277S425000, C277S433000, C277S554000, C277S555000
Reexamination Certificate
active
06224322
ABSTRACT:
BACKGROUND AND FIELD OF INVENTION
This invention relates to seals and more particularly relates to a novel and improved dynamic seal for pumps of the hydraulic sealing type and which are adaptable for use in pumping acids or slurries.
A. R. Wilfley & Sons, Inc. is the assignee of previously developed seals for centrifugal pumps which obviates the use of a packing gland or mechanical seal bearing directly against a rotating part but is capable of sealing against the leakage of liquid into the seal housing or reservoir when the pump is not in operation and has no hydraulic sealing capability. Conversely, when the pump is in operation, it will hydraulically seal against leakage of liquid from the expeller region into the seal housing or reservoir of the pump. For example, attention is directed to U.S. Pat. No. 5,667,356 to Whittier et al for ACID/SLURRY GOVERNOR ASSEMBLY FOR CENTRIFUGAL PUMPS.
Nevertheless, there is a continuing need for a dynamic seal of simplified construction which is conformable for use both with acids and slurries and which will prevent solids from settling into the cavity under the seal housing when the pump is not in operation, assists the expeller in solids evacuation from the expeller cavity and stationary seal faces, and effectively prevents the leakage of liquid from the expeller region into the seal housing of the pump when the pump is at rest. It is further desirable that the seal member have a variable spring constant according to its intended application and provided with outer sealing surfaces which can be composed of a material chemically compatible with the fluid to be sealed, flexible enough to withstand movement in adjusting to the width of the gap between the surfaces to be sealed and soft enough to form a liquid-tight seal with both confronting surfaces.
Other representative patents are U.S. Pat. No. 1,346,926 to Wilfley, U.S. Pat. No. 1,556,657 to Wilfley, U.S. Pat. No. 1,976,532 to Wilfley, U.S. Pat. No. 2,272,454 to Wilfley, U.S. Pat. No. 2,608,423 to Wilfley, U.S. Pat. No. 2,660,487 to Wilfley, U.S. Pat. No. 3,137,237 to Zagar et al, U.S. Pat. No. 3,472,169 to Dyke et al, U.S. Pat. No. 3,515,497 to Studebaker et al, U.S. Pat. No. 3,652,180 to Choquette et al and U.S. Pat. No. 4,915,579 to Whittier et al.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide for a novel and improved seal which is capable of spanning a gap between relatively rotating members and is self-adjusting to changes in the width of the gap.
It is another object of the present invention to provide for a novel and improved seal member for centrifugal pumps and the like which will prevent leakage of liquid or solids into the seal housing when the pump is not in operation; and specifically wherein the seal member is mounted so as to span the gap between a rotating expeller and seal housing and maintain a liquid-tight seal with confronting surfaces of the expeller and seal housing whereby to prevent solids from settling in the cavity under the seal housing when the pump is shut off, and assist the expeller in solids evacuation from the expeller cavity and stationary seal faces.
It is a further object of the present invention to provide for a novel and improved seal for centrifugal pumps incorporating a unique form of spring element having a profile which determines its spring constant and which can be specific to each pump size in order to compensate for the closing and opening force of the pump.
In accordance with the present invention, a barrier ring in the form of a dynamic seal member is interposed between generally radial wall portions which undergo relative axial movement as well as to vary the width of a gap between the portions, the seal member having an outer jacket of flexible material and an annular spring member inserted in a groove in the jacket wherein mounting of the seal member under compression between confronting surfaces of the relatively rotating portions will maintain liquid-tight sealing engagement with the confronting surfaces notwithstanding variations in the width of the gap. Preferably, the spring member is an endless or annular spring of generally conical configuration inserted in opposed facing grooves in the jacket and wherein the spring extends at an acute angle between the confronting surfaces to maintain sealing engagement with the surfaces notwithstanding variations in the width of the gap. In a modified form of invention, the spring member is an endless helical spring(s) inserted in a circumferentially extending groove(s) in the jacket. Most desirably, in the modified form, a pair of endless helical springs are employed in juxtaposed relation to one another in a pair of grooves in the jacket. A typical application of the barrier rings is to a centrifugal pump of the type having a seal housing in outer spaced surrounding relation to a drive shaft, an impeller and expeller mounted on the drive shaft forwardly of the seal housing with the expeller being operative to resist liquid flow into the seal housing when the drive shaft is rotated at a predetermined rate of speed, the annular barrier seal member being interposed in a gap between the expeller and seal housing, the gap increasing in width in response to axial movement of the seal housing away from the expeller when the drive shaft is not being rotated, the seal member including an outer jacket of a flexible material, an annular spring of generally conical configuration inserted in a groove in the jacket, the seal member extending at an acute angle between confronting surfaces of the expeller and the housing with opposite edges of the jacket maintaining sealing engagement with the expeller and housing notwithstanding variations in the width of the gap.
The above and other objects, advantages and features of the present invention will become more readily appreciated and understood from a consideration of the following detailed description of preferred and modified forms of the present invention when taken together with the accompanying drawings in which:
REFERENCES:
patent: 1346926 (1920-01-01), Wilfley
patent: 1556657 (1925-10-01), Wilfley
patent: 1893814 (1933-01-01), Widin
patent: 1976532 (1934-10-01), Wilfley
patent: 2049063 (1936-07-01), Hubbard
patent: 2266175 (1941-12-01), Delaval-Crow
patent: 2272454 (1942-02-01), Wilfley
patent: 2488465 (1949-11-01), Bourne, Jr.
patent: 2608423 (1952-08-01), Wilfley
patent: 2660487 (1953-11-01), Wilfley
patent: 3137237 (1964-06-01), Zagar et al.
patent: 3472169 (1969-10-01), Dyke et al.
patent: 3515497 (1970-06-01), Studebaker et al.
patent: 3652180 (1972-03-01), Choquette et al.
patent: 4133542 (1979-01-01), Janian et al.
patent: 4379558 (1983-04-01), Pippert
patent: 4508356 (1985-04-01), Janian
patent: 4789166 (1988-12-01), Rericha et al.
patent: 4915579 (1990-04-01), Whittier et al.
patent: 5667356 (1997-09-01), Whittier et al.
patent: 5791657 (1998-08-01), Cain et al.
patent: 5799953 (1998-09-01), Henderson
A. R. Wilfley & Sons, Inc.
Reilly John E.
Verdier Christopher
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