Horizontal agitator

Information

  • Patent Grant
  • 6572261
  • Patent Number
    6,572,261
  • Date Filed
    Tuesday, June 12, 2001
    23 years ago
  • Date Issued
    Tuesday, June 3, 2003
    21 years ago
Abstract
An agitator assembly for mounting in a wall of a storage tank that includes a body having a rotatable shaft extending therethrough. The body includes a duct having a diameter that is larger than the diameter of the shaft to allow passage of a fluid therebetween. An impeller is secured to one end of the shaft and a collar is secured to the other end. A bushing is provided between the body and the shaft and allows passage of a fluid during a cleaning cycle. A motor assembly is attached to the shaft and provides power for rotation of the shaft. A resilient member is provided over the shaft between the motor assembly and collar to control axial movement of the shaft. During a cleaning cycle, fluid pressure overcomes the biasing force of the compressible member permitting the fluid to escape the body to effectively clean the impeller.
Description




FIELD OF THE INVENTION




The present invention relates generally to an agitator apparatus, and more particularly to a horizontal agitator suitable for use in the food, dairy and beverage industries.




BACKGROUND OF THE INVENTION




In light of recent food safety issues, the USDA has become more aggressive in its acceptance criteria and inspections of equipment used in the food, dairy and beverage industries. The USDA has promulgated standards related to the cleanliness and cleanability of equipment used in these industries. Due to these standards, it is becoming increasingly more important for food, dairy and beverage producers to have equipment that is USDA accepted to stay competitive in the marketplace.




Agitators, and more particularly horizontal agitators, for use in the food, dairy and beverage industries are known in the art. Conventional agitators generally include an impeller attached to a rotatable shaft that is supported by a body. The body is placed within the wall of a storage tank so that the impeller blades are positioned toward the interior of the tank. The end of the shaft that is outside the storage tank is generally attached to a motor or other means to cause rotation of the shaft.




Conventional agitator designs suffer from several limitations that render them difficult to achieve USDA acceptance. In one known agitator design, an owner is required to climb into the tank, manually remove the exposed parts and individually clean the parts by hand. In another known agitator design, cleaning fluid is forced through the body and exits the nose of the agitator at high pressure to clean the impeller blades. In this design an owner is required to loosen a shaft collar and push the shaft forward by hand to disengage a nose seal from the agitator body. The movement of the shaft enables cleaning fluid to flow through the interior of the body to effectively clean the body and adjacent sealing surfaces. After cleaning, the owner must manually pull the shaft back and retighten the collar before operation. Over-tightening the collar can result in damage to the nose seal and under-tightening allows leakage into the body during a mixing operation.




Those skilled in the art continue to attempt to improve upon the designs of current horizontal agitators, particularly to improve their cleanability for USDA acceptance. The present invention provides an effective USDA-accepted, mechanically cleaned-in-place (CIP) horizontal agitator.




SUMMARY OF THE INVENTION




The present invention recognizes the aforementioned limitations associated with conventional horizontal agitators and provides a USDA-accepted, mechanically cleaned-in-place horizontal agitator assembly.




In accordance with an embodiment of the present invention, a horizontal agitator assembly is provided that includes an impeller secured to a shaft that is rotatably supported within a body. A sealing member is positioned on the shaft between the impeller and a distal end of the body to prevent the ingress of matter into the body. The body of the agitator assembly is disposed within the wall of a storage tank and is secured to the storage tank by a mounting assembly. The body is preferably a one-piece design having internally smooth surfaces that are free from crevices that can facilitate collection of undesirable foreign matter, such as bacteria. The body includes a rear seal assembly having a connection member attached thereto to secure the agitator assembly to a cleaning fluid source. A bushing comprising a self-lubricating polymer is disposed near the distal end of the body to support the shaft. The bushing is provided with internal and external grooves that allow passage of the cleaning fluid to effectively clean the shaft and impeller.




The mounting assembly supports the weight of a motor assembly that supplies rotative power to the shaft. A shaft housing is rotatably supported within the motor assembly and provides a means to attach the shaft to the motor assembly. An area of the shaft that is positioned within the shaft housing contains a plurality of radially extending teeth that engage the shaft housing. The end of the shaft opposite the impeller includes a plurality of threads that engage the internal threads of a shaft collar that is positioned on the shaft. A compressible member is positioned on the shaft between the shaft housing and the shaft collar.




During a CIP cycle, cleaning fluid enters the port in the rear seal assembly and travels between the body and the shaft to effectively clean the internal surfaces of the agitator assembly. A portion of the cleaning fluid is forced through the internal grooves of the bushing to clean the area of the shaft in proximity with the bushing. The remainder of the cleaning fluid is forced through the external grooves until it reaches the sealing member. Upon reaching the sealing member, the fluid pressure increases until the pressure overcomes the biasing force of the compressible member and forces the sealing member and shaft to move axially away from the distal end of the body permitting the cleaning fluid to escape. The escaping fluid is redirected by the contoured geometry of the distal end of the body to provide pressurized mechanical cleaning of the impeller blades and adjacent sealing surfaces during the CIP cycle.











The foregoing agitator assembly design is USDA accepted and may be cleaned-in-place without the need to disassemble the agitator and clean it by hand. Moreover, the agitator assembly automates the cleaning cycle by eliminating the need to loosen the shaft collar and push the shaft forward by hand. Various additional aspects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.




BRIEF DESCRIPTION OF THE DRAWINGS




The features and inventive aspects of the present invention will become more apparent upon reading the following detailed description, claims, and drawings, of which the following is a brief description:





FIG. 1

is a partial sectional view of an embodiment of the present invention showing the agitator assembly secured in a storage tank.





FIG. 1A

is an enlarged view of a duct distal end of the agitator assembly of FIG.


1


.





FIG. 1B

is an enlarged view of an engagement end of the agitator assembly of FIG.


1


.





FIG. 2

is a front view of a bushing according to the present invention.





FIG. 3

is a cross-sectional view of the bushing shown in FIG.


2


.











DESCRIPTION OF THE PREFERRED EMBODIMENT




Referring now to the drawings, the preferred embodiments of the present invention are described in detail. Referring to

FIG. 1

, a preferred embodiment of an agitator assembly


10


is shown mounted in a storage tank


12


. Agitator assembly


10


generally includes an impeller


14


secured to a shaft


16


that is rotatably supported in a body


18


. Agitator assembly further includes a mounting assembly


20


for securing agitator assembly


10


in tank


12


and for supporting a motor assembly


22


that supplies power to rotate shaft


16


.




Impeller


14


is preferably formed of a material suitable for use in the food, dairy or beverage industry, such as stainless steel or an FDA approved plastic. Impeller


14


generally includes a plurality of blades


24


that extend radially outwardly away from a hub


26


. Hub


26


includes a receiving portion


28


that receives a distal end


30


of shaft


16


. Impeller


14


is preferably welded to shaft


16


, but may be secured by other means known in the art.




Shaft


16


is also preferably formed of a material suitable for use in the food, dairy or beverage industry, such as stainless steel or an FDA approved plastic. Shaft


16


extends from distal end


30


to an engagement end


32


. Shaft


16


is rotatably supported within body


18


near distal end


30


by a bushing


34


and near engagement end


32


by motor assembly


22


. In this configuration, shaft


16


is capable of rotative and axial movement within body


18


. The portion of shaft


16


that is positioned within body


18


preferably includes a smooth surface


36


that is free of crevices. Engagement end


32


of shaft


16


preferably includes a plurality of threads


38


for engaging the corresponding internal threads (not illustrated) of a shaft collar


42


. Additionally, shaft


16


preferably includes a plurality of radially extending teeth


44


that are positioned to engage motor assembly


22


, as will be described in further detail below.




Body


18


is preferably a one-piece design formed of a strong material, such as stainless steel or an FDA approved high-strength plastic. Body


18


generally includes a duct


46


therethrough that extends from a duct distal end


48


to a rear seal assembly


50


. Referring to

FIG. 1A

, duct distal end


48


of body


18


includes a generally recessed and preferably flat surface


52


extending radially outwardly from duct


46


. Surface


52


terminates into a preferably contoured surface


54


that is designed to direct the flow of pressurized fluid, as will be described in further detail below. A sealing element


55


, having a preferably polymeric composition, is provided over distal end


30


of shaft


16


and is biased on one end by hub


26


. During a mixing operation, sealing element


55


sealingly engages flat surface


52


to prohibit the ingress of foreign matter into duct


46


.




Duct


46


generally includes a first interior surface


56


and a second interior surface


58


having a diameter that is preferably greater than the diameter of the first interior surface


56


. First and second interior surfaces


56


and


58


are preferably smooth and free from crevices to prevent the growth and accumulation of undesirable foreign matter, such as bacteria. First interior surface


56


extends from distal end


48


of body


18


to a preferably radially outwardly tapered surface


60


. Second interior surface


58


extends from surface


60


to a counterbore


62


positioned in rear seal assembly


50


. The diameter of second interior surface


58


is preferably sized to create an annular void between second interior surface


58


and shaft


16


to permit passage of cleaning fluid during a CIP operation, as will be described in detail below.




Rear seal assembly


50


is preferably secured to body


18


by a U-clamp


64


. An annular sealing element


66


, preferably having an elastomeric composition, is disposed within counterbore


62


to sealingly engage shaft


16


. A port


68


is formed preferably perpendicular to duct


46


to allow passage of a fluid into body


18


. A connecting member


70


is secured in port


68


to provide communication between a fluid source and duct


46


.




Bushing


34


is provided between shaft


16


and first interior surface


56


in body


18


. Referring to

FIGS. 2 and 3

, bushing


34


is preferably formed of a polymeric material, such as an FDA approved polybutylene teraphalate polyester, and more preferably of an internally-lubricated polymeric material that exhibits a high wear resistance and a low coefficient of friction. In a preferred embodiment, bushing


34


has a generally cylindrical cross-section that includes an inner surface


72


and an outer surface


74


. Inner surface


72


includes at least one, and preferably two, axial passageways


76


. Outer surface


74


includes a plurality of preferably equidistantly spaced axial passageways


78


. Passageways


76


permit fluid flow between shaft


16


and bushing


34


to clean shaft


16


. Similarly, passageways


78


permit fluid flow between bushing


34


and first interior surface


56


of body


18


to clean impeller


14


, interior surface


56


and bushing


34


.




Referring to

FIG. 1

, in a preferred embodiment, mounting assembly


20


is positioned to attach agitator assembly


10


to storage tank


12


and to generally support the weight of the components of agitator assembly


10


positioned on the exterior of storage tank


12


. Mounting assembly


20


preferably includes a first structural plate


80


secured to storage tank


12


at a predetermined angle. In a preferred embodiment, first structural plate


80


includes a plurality of threaded apertures


82


therethrough, each for receiving a fastener


84


such as a bolt. A second structural plate


85


is integrally formed with motor assembly


22


and includes a plurality of apertures


82




a


that correspond in position to apertures


82


in first structural plate


80


. Fastener


84


generally includes a cylindrical body


86


having a threaded engagement portion


88


on each end. Fastener


84


preferably includes at least one flat


90


for engagement by a wrench to secure fastener


84


into first plate


80


. Moreover, threaded engagement portion


88


is preferably longer on one end of fastener


84


such that, upon assembly of second plate


85


, the threads are exposed on the opposite side of second plate


85


. A nut


91


, such as an acorn nut, threadably engages the exposed threads of the fastener


84


to secure second plate


85


to fasteners


84


. An additional aperture


92


is provided in the center of the second plate


85


to allow passage of shaft


16


. A shaft housing


94


is rotatably supported within motor assembly


22


and provides a means to attach shaft


16


to motor assembly


22


. Shaft housing


94


includes a duct


96


therethrough for receiving shaft


16


. Duct


96


includes an inwardly facing groove having disposed therein an annular sealing element


100


, such as an o-ring, to prevent the ingress of contamination into duct


96


. Radially extending teeth


44


on shaft


16


engage the interior surface of duct


96


to permit only axial movement of shaft


16


in shaft housing


94


.




Motor assembly


22


is provided to supply power for rotation of shaft


16


and impeller


14


. In a preferred embodiment, motor assembly


22


includes a motor


102


, such as an electric motor, in communication with shaft housing


94


. Motor


102


may be attached to a transmission or placed directly in communication with shaft housing


94


. Preferably, motor


102


is positioned perpendicular to shaft housing


94


to permit the use of a helical gear between the motor shaft and shaft housing


94


. In this configuration, a helical gear is the preferred power transmission device given its ability to transmit motion and power between shafts that are positioned perpendicular to each other.




As illustrated in

FIGS. 1 and 1B

, a resilient member


104


, such as a spring, is preferably positioned between shaft collar


42


and a terminal end


106


of shaft housing


94


. A hinged guard assembly


108


is provided over terminal end


106


of shaft housing


94


, resilient member


104


and shaft collar


42


to enclose the exposed components. Resilient member


104


acts against shaft collar


42


which in turn forces shaft


16


in an axial direction that allows sealing element


55


to sealingly engage distal end


48


of body


18


. The sealing pressure of sealing element


55


against body


18


can be increased by rotating shaft collar


42


in a clockwise direction such that shaft collar


42


further compresses resilient member


104


. As resilient member


104


is compressed, the biasing force against shaft collar


42


and shaft


16


is increased resulting in an increase in the sealing pressure between sealing element


55


and body


18


and hub


26


.




The cleaning operation of the inventive agitator assembly


10


will be described with reference now to

FIGS. 1

,


2


and


3


. When it is desired to clean agitator assembly


10


, the user attaches a source of cleaning fluid by connecting a supply hose having a USDA-accepted terminal connector to connection member


70


. While the shaft is rotating, the cleaning fluid enters body


18


at port


68


where it is directed axially along shaft


16


through duct


46


. The smooth surfaces of shaft


16


and duct


46


permit the fluid to easily pick up any foreign matter within duct


46


. As the fluid is directed past surface


60


, the fluid velocity increases as it is forced into the area of body


18


occupied by bushing


34


. A portion of the fluid passes through grooves


76


on inner surface


72


of bushing


34


and a greater portion of the fluid passes through grooves


78


on outer surface


74


. The portion of the fluid that passes through grooves


76


serves to clean the portion of shaft


16


adjacent bushing


34


as it rotates. The greater portion of fluid that passes through grooves


78


acts against distal end


30


of shaft


16


and sealing member


55


. The fluid pressure against distal end


30


and sealing member


55


accumulates until the pressure overcomes the biasing force of resilient member


104


and forces distal end


30


of shaft


16


and impeller


14


axially away from body


18


. Upon movement of shaft


16


away from body


18


, the high-pressure fluid exits body


18


and is redirected by the contoured distal end


48


of body


18


to clean impeller blades


24


. Contoured surface


54


is preferably divided into four quadrants with at least one of the quadrants having a different radius than the other quadrants. The various radii of contoured surface


54


permit the fluid to be redirected to different areas of blades


24


as impeller


14


rotates.




Generally, a minimum fluid supply pressure of approximately 20 psi (1.4 bar) is all that is need to effectively clean agitator assembly


10


during the cleaning operation. However, the fluid supply pressure required to effect axial movement of shaft


16


can be varied by adjusting the position of shaft collar


42


or by varying the input fluid pressure. For example, to reduce the pressure required to move shaft


16


, shaft collar


42


may be rotated in a counterclockwise direction to decrease the compression of resilient member


104


. Alternatively, in order to increase the fluid pressure exiting the body at contoured distal end


48


, shaft collar


42


may be turned in a clockwise direction to increase the biasing force of resilient member


104


. The corresponding fluid pressure needed to overcome the increased biasing force of resilient member


104


will result in a greater fluid exit velocity at the contoured distal end


48


of body


18


. After completion of the CIP cycle, the supply hose is removed and the agitator is automatically placed back into operation.




Accordingly, the present invention provides a USDA accepted horizontal agitator assembly that automates cleaning by supplying pressurized cleaning fluid to the body, impeller blades and adjacent sealing surfaces during a CIP cycle. The design avoids the need to climb into the tank, manually disassemble the assembly, and clean the disassembled parts by hand.




Although certain preferred embodiments of the present invention have been described, the invention is not limited to the illustrations described and shown herein, which are deemed to be merely illustrative of the best modes of carrying out the invention. A person of ordinary skill in the art will realize that certain modifications and variations will come within the teachings of this invention and that such variations and modifications are within its spirit and the scope as defined by the claims.



Claims
  • 1. An agitator assembly for mounting in a wall of a storage tank, said agitator assembly comprising:a body member extending through said wall of said storage tank, said body member including a seal assembly that is in communication with a fluid source; a rotatable shaft extending longitudinally through said body member, said shaft extending from a distal end to an engagement end and having a substantially smooth inner surface adjacent said distal end; an impeller secured to said distal end of said shaft; a collar positioned on said engagement end of said shaft; an input device in communication with said shaft for supplying power to rotate said shaft; and a resilient member positioned over said shaft between said input device and said collar; whereby when a fluid is injected into said body, the fluid pressure increases until the pressure overcomes the biasing force of said resilient member and causes said shaft to move in an axial direction permitting the fluid to escape the body under pressure to effectively clean the impeller.
  • 2. The assembly of claim 1, wherein said body includes a duct having a diameter that is larger than the diameter of said shaft to allow passage of said fluid between said duct and said shaft.
  • 3. The assembly of claim 1, wherein said body includes a contoured portion for directing the pressurized fluid flow onto said impeller.
  • 4. The assembly of claim 3, wherein said contoured portion includes four quadrants with at least one quadrant having a different radius than the remaining quadrants.
  • 5. The assembly of claim 3, wherein a sealing element is positioned on said shaft to sealingly engage said contoured portion to prohibit the ingress of foreign matter into said body.
  • 6. The assembly of claim 1, further including a bushing disposed between said shaft and said body.
  • 7. The assembly of claim 6, wherein said bushing includes an inner surface having a least one groove and an outer surface having a plurality of grooves.
  • 8. The assembly of claim 7, wherein said bushing comprises a self-lubricating polymeric material exhibiting a high wear resistance and low coefficient of friction.
  • 9. The assembly of claim 1, wherein said impeller includes a plurality of blades that extend radially outwardly from a hub.
  • 10. The assembly of claim 1, further including a mounting assembly for securing said agitator assembly to said storage tank.
  • 11. The assembly of claim 1, wherein said input device is a motor assembly.
  • 12. The assembly of claim 11, wherein said motor assembly includes an electric motor attached to a gear arrangement that is in communication with a shaft housing having a duct for receiving said shaft.
  • 13. An agitator assembly for mounting in a wall of a storage tank, saidagitator assembly comprising: a body member extending through said wall of said storage tank, said body member including a contoured portion and a seal assembly that is in communication with a fluid source; a rotatable shaft extending longitudinally through said body member, said shaft extending from a distal end to an engagement end; a bushing disposed between said shaft and said body, said bushing including an inner surface having a least one groove and an outer surface having a plurality of grooves; an impeller secured to said distal end of said shaft; a sealing element positioned on said shaft to sealingly engage said contoured portion to prohibit the ingress of foreign matter into said body; an input device in communication with said shaft for supplying power to rotate said shaft; a collar positioned on said engagement end of said shaft; and a resilient member positioned over said shaft between said input device and said collar; whereby when a fluid is injected into said body, the fluid pressure increases until the pressure overcomes the biasing force of said resilient member and causes said shaft to move in an axial direction permitting the fluid to escape the body between said sealing element and said contoured portion to effectively clean the impeller.
  • 14. The assembly of claim 13, wherein said body includes a duct having a diameter that is larger than the diameter of said shaft to allow passage of a fluid between said duct and said shaft.
  • 15. The assembly of claim 13, wherein said contoured portion includes four quadrants with at least one quadrant having a different radius than the remaining quadrants.
  • 16. The assembly of claim 13, wherein said bushing comprises a self-lubricating polymeric material exhibiting a high wear resistance and low coefficient of friction.
  • 17. The assembly of claim 13, wherein said impeller includes a plurality of blades that extend radially outwardly from a hub.
  • 18. The assembly of claim 13, further including a mounting assembly for securing said agitator assembly to said storage tank.
  • 19. The assembly of claim 13, wherein said input device is a motor assembly.
  • 20. An agitator assembly for mounting in a wall of a storage tank, said agitator assembly comprising:a body member extending through said wall of said storage tank, said body member including a seal assembly that is in communication with a fluid source; a rotatable shaft extending longitudinally through said body member, said shaft extending from a distal end to an engagement end and having a substantially smooth surface adjacent said distal end; an impeller secured to said distal end of said shaft; a sealing element positioned on said shaft; an input device in communication with said shaft for supplying power to rotate said shaft; and a means for biasing said sealing element against said body member, wherein said means for biasing is positioned over said shaft and outside said body member.
  • 21. An agitator assembly for mounting in a wall of a storage tank, said agitator assembly comprising:a body member extending through said wall of said storage tank, said body member including a seal assembly that is in communication with a fluid source, and a contoured portion for directing the pressurized fluid flow onto said impeller, said contoured portion including four quadrants with at least one quadrant having a different radius than the remaining quadrants; a rotatable shaft extending longitudinally through said body member, said shaft extending from a distal end to an engagement end; an impeller secured to said distal end of said shaft; a collar positioned on said engagement end of said shaft; an input device in communication with said shaft for supplying power to rotate said shaft; and a resilient member positioned over said shaft between said input device and said collar; whereby when a fluid is injected into said body, the fluid pressure increases until the pressure overcomes the biasing force of said resilient member and causes said shaft to move in an axial direction permitting the fluid to escape the body under pressure to effectively clean the impeller.
  • 22. An agitator assembly for mounting in a wall of a storage tank, said agitator assembly comprising:a body member extending through said wall of said storage tank, said body member including a seal assembly that is in communication with a fluid source; a rotatable shaft extending longitudinally through said body member, said shaft extending from a distal end to an engagement end; a bushing disposed between said shaft and said body, wherein said bushing includes an inner surface having at least one groove and an outer surface having a plurality of grooves; an impeller secured to said distal end of said shaft; a collar positioned on said engagement end of said shaft; an input device in communication with said shaft for supplying power to rotate said shaft; and a resilient member positioned over said shaft between said input device and said collar; whereby when a fluid is injected into said body, the fluid pressure increases until the pressure overcomes the biasing force of said resilient member and causes said shaft to move in an axial direction permitting the fluid to escape the body under pressure to effectively clean the impeller.
  • 23. The assembly of claim 22, wherein said bushing comprises a self-lubricating polymeric material exhibiting a high wear resistance and low coefficient of friction.
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Entry
Paul Mueller Company—patent-pending, USDA 3-A accepted, horizontal agitator Web-site: http://www.muel.com/products/processing/foodanddairy/siloHorizontalAgitation.cfm.cfm.