US3526467A - Agitator impeller - Google Patents

Description

Sept. 1, 1970 D. L. KlME AGITATOR IMPELLER Filed Aug. 23., 1968 '//VVENTOR DONALD L. KIME W Wz,

I ATTORNEYS United States Patent O 3,526,467 AGITATOR IMPELLER Donald L. Kime, Dayton, Ohio, assignor to Chemineer, Inc., Dayton, Ohio, a corporation of Ohio Filed Aug. 23, 1968, Ser. No. 754,770 Int. Cl. B44d 3/06 U.S. Cl. 416-200 4 Claims ABSTRACT OF THE DISCLOSURE An agitator impeller includes an upper section and a lower section each having a hub and outwardly projecting blades, and the blades of both Sections are arranged to have Substantially the same path. A shaft extension projects upwardly from the hub of the lower section through the hub of the upper section and is threadably connected to the lower end of a drive shaft to effect a self-tightening connection of the Sections to the shaft.

BACKGROUND OF THE INVENTION In an agitator including a prime mover connected to drive a shaft adapted to depend into a container or tank defining a mixing chamber, it is common to employ an impeller having a Split hub formed in two mating sections each supporting a plurality of either curved or flat blades attached to the hub Sections by threaded fasteners such as ScrewS or bolts. The hub Sections are clamped together on the drive shaft with transversely extending screws so that the impeller can be disassembled and in- Serted in Sections into the mixing chamber through a cover opening which is Substantially smaller in diameter than the overall diameter of the impeller. The Sections of the impeller are re-assembled onto the drive shaft usually by inserting the hands through the opening and inserting the Screws into the hub Sections.

In some agitator installations, it is not only desirable to construct the impeller in Sections for inserting into the mixing Chamber through a small opening, but it is also desirable to eliminate all exposed fasteners. For example, when using such an impeller in a sanitary installation for mixing a food product, it is desirable to eliminate exposed fasteners and to mini'mize corner cre'vices so that the impeller does not collect and retain portions of the material being mixed and can be easily cleaned. As another example, when it is necessary to provide the impeller with a coating such as a plastic or rubber coating to prevent corrosion, exposed fasteners should be avoided to provide maximum corrosion resistance and a good bond of the coating to the impeller.

SUMMARY OF THE INVENTION The present invention is directed to an improved impeller adapted for mounting on the drive shaft of an agitator and which provides the important features of sectional construction for inserting the impeller in Sections through a small opening, the elimination of exposed fasteners and a simplified and economical construction which provides for a Self-tightening connection of the impeller onto the drive shaft when the impeller is being driven. In accordance with one embodiment of the invention, the impeller includes an upper section and a lower section each having a generally cylindrical hub and a pair of diametrically opposed blades. A solid shaft extension projects upwardly from the hub of the lower section through the hub of the upper section and has an upper end portion which is threaded into a hole formed in the lower end of the drive shaft. The upper section of the impeller is keyed to the shaft extension to assure common rotation of the upper and lower Sections in a fixed anice nular relation, and the blades are arranged so that they each have the same path.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of an impeller constructed in accordance with the invention;

FIG. 2 is a perspective exploded view of the impeller shown in FIG. 1;

FIG. 3 is an elevational view of the impeller shown in FIGS. 1 and 2 with a portion shown in axial section;

FIG. 4 is a perspective view of an impeller forming another embodiment of the invention; and

FIG. 5 is a fragmentary elevational view of the impeller shown in FIG. 4.

DESCRIPTION 'OF THE PREFERRED EMB ODIMENTS Referring to the drawing, FIGS. 1-3 show one embodiment of an impeller 10 which is mounted on the lower end of an agitator drive shaft 12 having a threaded axial hole 13. The impeller 10 includes an upper section 14 and a lower section 16. The upper section 14 has a cylindrical hub 18 with a central bore 20 interrupted by an axially extending keyway 21. A pair of diametrically opposed flat blades 25 project outwardly from the hub 18 in an axial plane, and eah blade 25 includes a downwardly and outwardly extending portion 26 located adjacent the hub 18 so that the outer radially extending portions of the blades 25 are offset downwardly in relation to the hub 18.

I The lower section 16 of the impeller 10 includes a cylindrical hub 28 having an outer diameter the same as that of the hub 18 of the upper section 14. A pair of diametrically opposed flat blades 30 project outwardly from the hub 28 in an axial plane and are arranged at 90 in relation to the blades 25. Each blade 30 includes an upwardly and outwardly projecting portion 32 adjacent the hub 28 so that the outer radially extending portions of the blades 30 are offset upwardly in relation to the hub 28 to have the same path as the outer portions of the blades 25.

A cylindrical shaft extension 35 is formed integrally with the hub 28 of the lower section 16 and projects upwardly through the bore 20 of the hub 18. A key 36 is mounted within a groove 37 formed within the shaft extension 35 and projects into the keyway 21 within the hub 18 so that the upper section 14 is rigidly connected to the lower section 16 with the blades 25 extending normally to the blades 30.

The shaft extension 35 includes a threaded upper end portion 38 which is threaded into the hole 13 within the lower end of the drive shaft 12. A resilient washer 40 is located between the hubs 18 and 28, and a resilient washer 42 is located between the lower end of the drive shaft 12 and the upper end of the hub 18 to form fiuid tight seals between the irnpeller Sections 14 and 16 and between the drive shaft 12 and the upper impeller section 14.

Referring to FIGS. 4 and 5 which Show another embodiment of the invention, an impeller is constructed Similar to the impeller 10 and includes an upper section 52 and a lower section 54. The upper Section 52 has a cylindrical hub 55 constructed Substantally the Same as the hub 18 of the impeller 10, that is, with a cylindrical bore 56 having an axially extending keyway 57. A pair of diametrically oposed flat blades 60 are welded to the hub 55 and are pitched by an angle of approximately 45 in relation to the axis of the hub 55.

The lower impeller section 54 includes a cylindrical hub having an outer diameter the Same as the hub 55, and a shaft extension 66, constructed substantially the Same as the shaft extension 35, projects upwardly through the bore 56 of the hub 55. A key 67 secures the hub 55 to the shaft extension 66 which has an upper end portion '68 threaded into the hole 13 within the lower end of the drive shaft 12. A pair of diametrically opposed flat blades 70 are welded to the hub 65 of the lower section 54 and are ptched at the same angle as the blades 60 of the upper section 52. Thus the outer configuration of the lower impeller section 54 is substantially identical to that of the upper section 52.

As shown in FIG. 5, the blades `60 extend downwardly in relation to the hub 55, and the blades 70 extend upwardly in relation to the hub 65 So that each of the blades 60 and 70 have the same path when the shaft 12 is rotated. Resilient washers 72 and 74 are mounted on the shaft extension 66 in the same manner as the washers 40 and 42 to form a fluid tight seal between the hubs 55 and 65 and between the lower end of the shaft 12 of the hub 55.

From the drawing and the above description, it is apparent that an impeller constructed in accordance with the invention provides desirable features and advantages. For example, by forming the shaft extension 35 as part of the lower section 16 of the impeller and by extending the shaft extension 35 upwardly through the hub of the upper section 14 for threading into the hole 13, a self-tightening connection is formed between the impeller 10 and the drive shaft 12 when right hand threads are used and the shaft 12 is driven in the direction of the arrow shown in FIG. 1. The construction of the impeller 50 forms a similar self-tightening connection. Furthermore, the assembly of the impeller 10 or the impeller 50 onto the drive shaft 12 can be performed quickly and without the use of exposed fasteners, which is especially desirable When the upper and lower Sections of the impeller are coated with a plastic or rubber coating or when the impeller is used in a sanitary installation for mixing a food product.

The impeller construction of the invention also provides for inserting and assembling of the impeller through a circular opening having a diameter substantially smaller than the overall diameter of the impeller. That is, each section of the impeller can be inserted separately through the opening and then be conveniently and quickly assembled onto the end of the drive shaft 12. The impeller construction also provides for minimizing the outer diameter of the hub of the upper and lower Sections which is desirable not only from an economical standpoint but also for obtaining optimum performance.

Another important advantage is provided by the offset relation of the blades 25 and 30 or the blades 60 and 70 in relation to their corresponding supporting hubs. That is, by extending the upper blades downwardly and the lower blades upwardly so that all blades have the same path, the impeller is provided with a balance construction which is important for eliminating any significant vibration within the agitator. Furthermore, the common path of all of the blades enables the use of performance charts for conventional impellers to predict the performance of an impeller constructed in accordance with the invention.

While the two impeller embodiments of the invention illustrated in the drawing each employ a set of flat blades, it is to be understood that it is within the scope of the invention to provide each impeller section with a set of curved blades according to the particular mixing action desired from impeller. It is also within the scope of the invention to form the stud shaft 35 as an integral portion of the drive shaft 12 and thread the shaft 35 into the hub 28 of the lower impeller section 16. Furthermore, it is within the scope of the invention to extend the shaft 35 and to mount one or more intermediate impeller sections, similar to the section 14, on the extended shaft to effect additional agitation.

While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. An improved impeller adapted for convenient mounting on an agitator drive shaft, comprising a lower section and an upper section each including a hub and blade means projecting outwardly from said hub, means defining an opening within said hub of said upper section, a shaft extension rigidly secured to said hub of said lower section and extending upwardly through said opening within said hub of said upper section, key means for rigidly connecting said hub of said upper section to said hub of said lower section to effect positive common rotation of said sections, said shaft extension including an upper end portion projecting above said hub of said upper section, and said upper end portion having external threads for engaging a threaded hole formed within the lower end of said drive shaft to effect a positive self-tightening connection of said Sections to said drive shaft in response to relative rotation between said Sections and said drive shaft.

2. An impeller as defined in claim 1 wherein said blade means of each said section comprise a pair of diametrically opposed substantially flat blades, said blades of said Sections are offset axially of their corresponding said hubs and are disposed in interfitting relation causing all of said blades to have substantially the same path, and said hubs have a combined axial length substantially no greater than the width of said blades in an axial direction.

3. An impeller as defined in claim 1 wherein said blade means of each said section comprise a pair of diametrically opposite substantially coplanar blades.

4. An improved impeller adapted for convenient mounting on an agitator drive shaft, comprising a lower section and an upper Section each including a generally cylindrcal hub and at least one substantially fiat blade projecting outwardly from said hub, said blades of said upper and lower Sections being offset axially of their corresponding said hubs and being disposed in interfitting relation causing all of said blades to have substantially the same rotational path, said hubs having a combined axial length substantially no greater than the width of said blades in an axial direction. A shaft extension rigidly connected to said hub of said lower section and projecting upwardly therefrom, means defining an opening within said hub of said upper section for receiving said shaft extension, key means for rigidly connecting Said hub of said upper section to said hub of said lower section to provide for positive common rotation of said upper and lower sections in fixed angular relation, said shaft extension including an upper end portion projecting above said hub of said upper section, and said upper end portion having external threads for engaging a threaded hole within the lower end of the drive shaft to effect a self-tightening connection of said Sections to said shaft in response to relative rotation between said Sections and said drive shaft.

References Cited UNITED STATES PATENTS 1,519,533 12/1924 Dingle 259-134 2,172,72l 9/1939 Wigzell -171 X 2,589,558 3/1952 Lamoreaux 259-134 2,811,339 10/1957 Osborne et al. 259-134 3,294,365 12/ 1966 Wilde et al. 170-165 X EVERETTE A. POWELL, JR., Primary Examiner

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