Rotary kinetic fluid motors or pumps – With cutter or comminutor for debris in working fluid
Reexamination Certificate
1999-02-12
2001-02-20
Lopez, F. Daniel (Department: 3745)
Rotary kinetic fluid motors or pumps
With cutter or comminutor for debris in working fluid
C415S206000
Reexamination Certificate
active
06190121
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to centrifugal pumps, and in particular, pumps of this type that have a chopping or cutting capability.
A variety of centrifugal pumps are known currently which are capable of pumping liquids and slurries containing solid matter such as small pieces of garbage or other disposed items. These pumps have the capability of chopping or cutting solid matter in the liquid mixture permitting the output from the pump to be disposed of more readily.
U.S. Pat. No. 3,155,046 issued Nov. 3, 1964 to James E. Vaughan describes a centrifugal pump for pumping a mixture of liquid and stringy solid material that includes a housing with a peripheral wall having a discharge aperture therein, a closed end, and an open end. The pump has an impeller secured on a shaft and the impeller has radially disposed impeller blades. Edges of these vanes adjacent to the pump inlet co-operate with sharpened edges of pump inlet apertures to cut solid material entering the pump.
One pump known in the prior art is the ABS “Piranha” Grinder pump. This pump incorporates sharpened spiral cutting grooves on the inside of an intake plate of the pump. Front edges on the impeller vanes of the pump rotate against the grooves to produce a cutting action. The edges of the vanes are flat in profile. This pump design is susceptible to binding problems from material being wedged between the impeller edges and the intake plate.
Another known pump is the Vaughan chopper pump disclosed in U.S. Pat. No. 5,256,032 issued Oct. 26, 1993. Features to chop and expel material from behind the impeller of the pump are incorporated into the design. The pump incorporates elongated curved vanes of the impeller operating in close cutting relationship with axially protruding ribs on a back plate of the casing. The vanes of the pump produce a cutting action as they pass over the ribs on the back plate.
Yet another known centrifugal pump is the screw centrifugal pump which utilizes spiral grooves in the rear face of the impeller of the pump and on the back plate of the casing of the pump. The rotating groove in the rear of the impeller operates against the stationary grooves in the casing backplate providing the function of discharging solids from the space between the backplate and impeller of the pump.
An object of the present invention is to provide a novel and durable centrifugal pump effective for pumping a mixture including solids suspended in a liquid.
A further object of the invention is to provide a centrifugal pump having an improved impeller with both radially extending vanes and a generally radial, partial back shroud with sharpened leading shroud edges that cooperate with grooves formed on a back plate of the pump casing. The sharpened shroud edges and the grooves interact to cut solids that have entered the pump through the intake port.
SUMMARY OF THE INVENTION
According to one aspect of the invention, a centrifugal pump capable of cutting solid matter in a liquid comprises a rotatable drive shaft defining an axis of rotation, an impeller mounted on this drive shaft, and a pump casing. The impeller has a set of radially extending vanes and a generally radial, partial back shroud that extends between the vanes and has substantial cutouts positioned between the vanes to make the back shroud a partial shroud. Sharpened with sharpened leading shroud edges are provided along sides of the cutouts. The vanes project generally forwardly from the shroud and towards an intake port of the pump. A casing includes a bowl encircling the impeller and forms the intake port adjacent to a front side of the impeller. The casing further includes a back plate adjacent to the back shroud, this back plate having spiral grooves facing the back shroud. The sharpened shroud edges and the spiral grooves interact to cut solids that have entered the pump through the intake port.
Preferably the vanes are curved and the leading shroud edges are beveled and serrated.
According to another aspect of the invention, a centrifugal pump suitable for pumping a liquid mixture containing solids includes a rotatable drive shaft defining an axis of rotation and an impeller mounted on this drive shaft for rotation therewith. The impeller has radially extending vanes and a generally radial, partial back shroud located at rear edges of the vanes. The shroud extends between the vanes and has substantial cutouts located between adjacent vanes to make the shroud a partial shroud. Leading shroud edges, are formed along sides of the cutouts which are sharpened. The pump also has a pump casing for forming a pump bowl that surrounds the impeller, an intake port adjacent to a front side of the impeller, and a pump outlet. The pump casing includes a back plate located next to the back shroud and having spiral shaped grooves extending circumferentially thereon and facing the back shroud. The shaft extends through this back plate. The sharpened shroud edges and the grooves interact to cut solids that have entered into the pump bowl.
In the preferred embodiment, the pump casing includes an intake plate that forms the intake port and at least a portion of the inner sidewall of this intake plate has spiral grooves which interact with sharpened front edges of the vanes to provide further cutting of solids entering the pump.
According to a further aspect of the invention, a centrifugal pump suitable for pumping a liquid mixture containing solids includes a rotatable drive shaft, an impeller mounted on this drive shaft and a pump casing for forming a pump bowl that surrounds the impeller. The impeller has at least several radially extending vanes and a partial back shroud located at rear edges of these vanes. The shroud has cutouts located between adjacent vanes and forming leading shroud edges adapted for cutting the solids. The casing also forms an intake port adjacent to a front side of the impeller and a pump outlet. A back plate of the casing is located adjacent the back shroud and has elongate cutting edges that extend at a substantial angle to the leading shroud edges that are adapted for cutting. These leading shroud edges and the cutting edges on the back plate closely interact to cut solids that have entered into the pump bowl.
Preferably the cutting edges on the back plate are formed by at least one spiral shaped groove formed on an inner surface of the back plate.
In a preferred embodiment of the pump, a disintegrator is mounted on the end of the drive shaft to provide initial cutting of solids as they enter the pump through the intake port.
Further features and advantages will become apparent from the following detailed description of a preferred embodiment, taken into conjunction with the accompanying drawings.
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Tsurumi Manufacturing Co. Ltd., Rugged, Powerful Tsuru
Cohen Carlos
Hayward John
Baker & Daniels
Hayward Gordon Limited
Lopez F. Daniel
McAleenan James M
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