Patent Grant
10487835
The present invention relates to a cutter assembly and high volume submersible shredder pump. These are for reducing the size of solids within a liquid which is to be pumped by chopping, shredding, cutting or grinding.
There is great commercial interest in centrifugal pumps which are capable of pumping liquids and slurries containing solid matter such as small pieces of disposed items. These pumps have the capability of chopping, shredding, cutting or grinding solid matter in the liquid mixture permitting the output from the pump to be disposed of more readily. Shredding pumps are used in liquid transfer applications that require size reduction for solid or semisolid materials contained in a liquid, in order to cut or shred such materials. The pump of the present invention includes an improved cutting assembly which is particularly useful when mounted to the suction side of submersible pumps that pump raw sewage, fish silage, byproducts of slaughter houses, waste water of paper mills and similar tough applications. These solid or semisolid materials are reduced in size such that a slurry is formed, which is more easily pumped than the solids themselves. Known grinder pumps have an inlet connected to a pumping chamber, and a driven shaft extending through the pumping chamber and into the inlet. The shaft rotates a cutting cylinder or disk in proximity to a plate cutter, thereby effecting the cutting action of the pump. Many other variations and configurations of grinder pumps are known, which provide shearing action between parts operating cooperatively at close tolerances. Examples of such pumps are disclosed in prior U.S. Pat. Nos. 3,650,081; 3,961,758; 4,108,386; 4,378,093; 4,454,993; 4,640,666; 4,697,746; 4,842,479; 5,016,825; 5,044,566; 5,256,032; 6,010,086; and 6,190,121.
U.S. Pat. No. 7,159,806 provides a cutting assembly for a grinder pump comprised of a rotary cutter rotatable against an opposing plate cutter. The cutting edges of the plate cutter include a plurality of V-slice cutting teeth, which create bridging spaces to pinch material which is being sucked in to ports and begin cutting along the V-slice and then for cut material to pass through and onward into the volute of the pump. The rotary cutter has a ground edge with a rake angle which shears the gathered material in cooperation with the cutting edges of the plate cutter. The grinder pump of U.S. Pat. No. 7,159,806 has an inner surface wall cover provided with a plurality of spiral grooves. These spiral grooves work cooperatively with the vanes of an impeller to outwardly eject any solid debris that begins to accumulate between the impeller vanes and wall. The impeller vanes of U.S. Pat. No. 7,159,806 are flat on the surface which meets the spiral grooves.
U.S. Pat. No. 8,784,038 provides a cutter assembly employing cutting lobes having a grooved surface which mate with corresponding grooves of a circular plate cutter. As a result, many more cutting surfaces are provided which more effectively and quickly shred the solid materials within the liquid to be expelled. The mechanism of U.S. Pat. No. 8,784,038 comprises a stationary perforated disc which is mounted to the suction casing of the pump and a shredder that is fastened to a rotating shaft. The interface of these two parts performs the shredding. The liquid moves thru the holes in the stationary plate and is then pumped out. The solids that are larger than the holes in the stationary plate are immediately reduced in size by the rotating portion of the shredder mechanism.
A problem with the mechanism of U.S. Pat. No. 8,784,038 is that it has a flat stationary disc and a flat rotary cutter such that some of the waste contents which are ground up are too large and have a tendency to clog the associated shredder pump. The present invention improves upon the cutter assembly of U.S. Pat. No. 8,784,038 by providing a more aggressive cutter arrangement including a cup-shaped, concave, plate cutter which mates with a corresponding rotary cutter having a plurality of cutting lobes. The inside walls of the cup-shaped, concave, plate cutter has a plurality of spaced apart concentric grooves and a concentric dividing wall between adjacent grooves. The underside of each of the cutting lobes has corresponding concentric grooves and concentric dividing walls which juxtapose and mate with those of the cup-shaped, concave, plate cutter. In operation the waste water contents have a much finer grind which improves efficient removal and reduces the likelihood of shredder pump clogging.
The invention provides a cutting assembly comprising:
a) a drive shaft alternately rotatable in a first direction of rotation and a second direction of rotation;
b) a rotary cutter rotatably fixed to said drive shaft; the rotary cutter comprising a circular hub having a bore through a central axis of the hub, and an implement for fixing the drive shaft to the hub within the bore; a plurality of cutting lobes, each of said cutting lobes having an upper surface, a lower surface opposite to the upper surface, a leading edge and a trailing edge opposite to the leading edge; each cutting lobe having an aperture therethrough extending from and through the upper surface to and through the lower surface; each of the cutting lobes extending outwardly from the hub such that a center line equidistant between the leading edge and the trailing edge of each cutting lobe is substantially perpendicular to the central axis of the hub; the cutting lobes being distributed around a periphery of the hub such that each of the distances from the leading edge of each cutting lobe to the trailing edge of a next adjacent cutting lobe are substantially equal; the lower surface of each cutting lobe having a plurality of spaced apart grooves and a dividing wall between adjacent grooves, the grooves and dividing walls of each cutting lobe extending either from its leading edge to its trailing edge or from its leading edge to its aperture and from its aperture to its trailing edge; each of said grooves and dividing walls having the shape of an arc of a circle which is concentric with the central axis of the hub;
c) a cup-shaped, concave, plate cutter having a circular horizontal cross-section, the plate cutter adapted for mounting to an intake opening of a stationary volute, said plate cutter having one or more side walls terminating at a floor, and a central plate bore through the floor, each of the side walls having an inner surface having a plurality of spaced apart concentric grooves and a concentric dividing wall between adjacent grooves; each of the grooves and each of the dividing walls having the shape of an arc of a circle which is concentric with a central axis of the bore of the plate cutter; the drive shaft being mounted for rotation within the plate bore of the plate cutter; the plate cutter having a plurality of holes through the one or more side walls; the grooves and dividing walls from the lower surface of each cutting lobe being juxtaposed with corresponding dividing walls and grooves from the plate cutter.
The invention also provides shredder pump comprising:
i) a stationary volute having an intake opening, and a discharge opening;
ii) a cutting assembly mounted in front of the intake opening, comprising:
a) a drive shaft alternately rotatable in a first direction of rotation and a second direction of rotation;
b) a rotary cutter rotatably fixed to said drive shaft; the rotary cutter comprising a circular hub having a bore through a central axis of the hub, and an implement for fixing the drive shaft to the hub within the bore; a plurality of cutting lobes, each of said cutting lobes having an upper surface, a lower surface opposite to the upper surface, a leading edge and a trailing edge opposite to the leading edge; each cutting lobe having an aperture therethrough extending from and through the upper surface to and through the lower surface; each of the cutting lobes extending outwardly from the hub such that a center line equidistant between the leading edge and the trailing edge of each cutting lobe is substantially perpendicular to the central axis of the hub; the cutting lobes being distributed around a periphery of the hub such that each of the distances from the leading edge of each cutting lobe to the trailing edge of a next adjacent cutting lobe are substantially equal; the lower surface of each cutting lobe having a plurality of spaced apart grooves and a dividing wall between adjacent grooves, the grooves and dividing walls of each cutting lobe extending either from its leading edge to its trailing edge or from its leading edge to its aperture and from its aperture to its trailing edge; each of said grooves and dividing walls having the shape of an arc of a circle which is concentric with the central axis of the hub;
c) a cup-shaped, concave, plate cutter having a circular horizontal cross-section, the plate cutter adapted for mounting to an intake opening of a stationary volute, said plate cutter having one or more side walls terminating at a floor, and a central plate bore through the floor, each of the side walls having an inner surface having a plurality of spaced apart concentric grooves and a concentric dividing wall between adjacent grooves; each of the grooves and each of the dividing walls having the shape of an arc of a circle which is concentric with a central axis of the bore of the plate cutter; the drive shaft being mounted for rotation within the plate bore of the plate cutter; the plate cutter having a plurality of holes through the one or more side walls; the grooves and dividing walls from the lower surface of each cutting lobe being juxtaposed with corresponding dividing walls and grooves from the plate cutter; wherein the drive shaft is mounted for rotation through a wall of the volute by a bearing and sealed by a mechanical seal;
iii) an impeller in the volute fixed around the drive shaft;
iv) an electric motor attached to an outer portion of the volute, and fixed to the drive shaft for rotating the drive shaft within the volute.
The invention further provides a method of shredding a solid within a liquid comprising:
I) providing a shredder pump comprising:
i) a stationary volute having an intake opening, and a discharge opening;
ii) a cutting assembly mounted in front of the intake opening, comprising:
a) a drive shaft alternately rotatable in a first direction of rotation and a second direction of rotation;
b) a rotary cutter rotatably fixed to said drive shaft; the rotary cutter comprising a circular hub having a bore through a central axis of the hub, and an implement for fixing the drive shaft to the hub within the bore; a plurality of cutting lobes, each of said cutting lobes having an upper surface, a lower surface opposite to the upper surface, a leading edge and a trailing edge opposite to the leading edge; each cutting lobe having an aperture therethrough extending from and through the upper surface to and through the lower surface; each of the cutting lobes extending outwardly from the hub such that a center line equidistant between the leading edge and the trailing edge of each cutting lobe is substantially perpendicular to the central axis of the hub; the cutting lobes being distributed around a periphery of the hub such that each of the distances from the leading edge of each cutting lobe to the trailing edge of a next adjacent cutting lobe are substantially equal; the lower surface of each cutting lobe having a plurality of spaced apart grooves and a dividing wall between adjacent grooves, the grooves and dividing walls of each cutting lobe extending either from its leading edge to its trailing edge or from its leading edge to its aperture and from its aperture to its trailing edge; each of said grooves and dividing walls having the shape of an arc of a circle which is concentric with the central axis of the hub;
c) a cup-shaped, concave, plate cutter having a circular horizontal cross-section, the plate cutter adapted for mounting to an intake opening of a stationary volute, said plate cutter having one or more side walls terminating at a floor, and a central plate bore through the floor, each of the side walls having an inner surface having a plurality of spaced apart concentric grooves and a concentric dividing wall between adjacent grooves; each of the grooves and each of the dividing walls having the shape of an arc of a circle which is concentric with a central axis of the bore of the plate cutter; the drive shaft being mounted for rotation within the plate bore of the plate cutter; the plate cutter having a plurality of holes through the one or more side walls; the grooves and dividing walls from the lower surface of each cutting lobe being juxtaposed with corresponding dividing walls and grooves from the plate cutter; wherein the drive shaft is mounted for rotation through a wall of the volute by a bearing and sealed by a mechanical seal;
iii) an impeller in the volute fixed around the drive shaft;
iv) an electric motor attached to an outer portion of the volute, and fixed to the drive shaft for rotating the drive shaft within the volute;
II) causing the electric motor to rotate the drive shaft in at least one direction of rotation;
III) passing the liquid, and the solid, through the cutting assembly and into the volute, and then causing the impeller to propel the liquid and the solid through the discharge opening.
As best seen in
The circular plate cutter 40 has a central plate bore for receiving shaft 14, and a surface having a plurality of concentric grooves 44 and a dividing wall 46 between adjacent grooves 44. Each of the grooves 44 have the shape of an arc of a circle which is concentric with a central axis of the bore, as well as the hub a rotary cutter 16. The drive shaft 14 is mounted for rotation within the circular plate cutter bore. In this embodiment, the plate cutter 40 has a plurality of holes 48 extending completely therethrough from its top surface to its bottom surface. Although shown as circular holes in
The grooves 36 and dividing walls 38 from the lower surface of each cutting lobe 24 and corresponding dividing walls 46 and grooves 44 from the circular plate cutter 40, may have any convenient shape. In one embodiment, each of the grooves and dividing wall between adjacent grooves form a generally rectangular shaped cross-section as seen in
The mating grooves and dividing walls of the cutting lobes 24 and the circular plate cutter 40 present an improvement over the prior art by providing a much greater shredding surface area for size reduction of solids within liquids. In addition, the lobes having leading and trailing edges and central apertures in combination with the plurality of holes through the surface of the plate cutter, provide a much greater number of cutting edges for the reduction of solids.
In order to calculate at the net “Flow Area”, which is the equivalent area of a non-obstructed volute inlet opening, one deducts the area that is constantly being obstructed by the rotating cutter. Therefore, Net “Flow Area”=Total Area of the holes in the stationary circular plate cutter—Total Area being obstructed by the rotating rotary cutter. In the embodiment described herein having an aperture in each of the lobes of the rotating cutter lobes two distinct advantages are obtained, namely a reduction in the area being obstructed by the rotating cutter, which in turn increases the Net “Flow Area”, and an increase in the number of contact edges. Thus one prior art shredder pump claim 108 cuts per revolution. A non-exclusive example of the use of the inventive shredder pump may well shred solids at a rate of from about 1000 to about 3000 cuts per revolution.
In use, the invention further provides a method of shredding a solid within a liquid comprising first providing the above described a shredder pump; then causing the electric motor to rotate the drive shaft in at least one direction of rotation; then passing a liquid, and an optional solid, through the cutting assembly and into the volute, and then causing the impeller to propel the liquid and the optional solid through the discharge opening.
The cupped feature of these embodiments represents an advantage over the prior art flat cutter disc in that it keeps the solids captive while being shredded. The flat disc type shreds a portion of the solid item as it is sucked in, but then slings it out and returns into the liquid until is sucked in again by the pump. The cutter of this invention demonstrates that once a solid, such as a garment, gets sucked in the cupped cutter assembly, it stays there until it is completely shredded.
While the present invention has been particularly shown and described with reference to preferred embodiments, it will be readily appreciated by those of ordinary skill in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. It is intended that the claims be interpreted to cover the disclosed embodiment, those alternatives which have been discussed above and all equivalents thereto.
| Number | Name | Date | Kind |
|---|---|---|---|
| 6367723 | Kircher | Apr 2002 | B1 |
| 8784038 | Ciotola | Jul 2014 | B2 |
