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Патент USA US3061761

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Oct .
30, 1962
Filed July 7, 1959
sew/1v STEL 25/?
United States Patent O?lice
Patented Oct. 30, 1962
same being realized and attained by means of the instru
Erwin Stelzer, Landfurtweg 66, Warburg,
Westphalia, Germany
Filed July 7, 1959, Ser. No. 825,546
Claims priority, application Germany July 7, 1958
8 Claims. (Cl. 310-269)
mentalities and combinations pointed out in the appended
In the accompanying drawing which forms part of this
speci?cation, one embodiment of the apparatus pursuant
to the invention is illustrated merely by way of example.
in the following description and in the claims, parts
will be identi?ed by speci?c names for convenience, but
such names are intended to be as generic in their applica
This invention relates to drive means for mixing, blend 10 tion to similar parts as the art will permit. Like reference
ing and like apparatus, and in particular refers to electric
characters denote like parts in the drawing, which latter is
drive means for agitators.
a cross-section of the head of an agitator or paddle shaft
There are known electric drive means of this kind for
and a slow speed electric motor, partly broken away,
machines, which are mounted on the cover of the agitator
directly mounted on said shaft.
vessel and include an electric motor and a gear reducer 15
for driving the agitator shaft. When sensitive materials
Referring now more particularly to the attached draw
ing there is disclosed a bushing 2 detachably mounted on
the vertical hollow shaft 1 of an agitator by means of a
concentric bushing 3 and a cone-shaped bushing 4 which
?ts over a correspondingly cone-shaped bushing 33 abut
are to be handled in the apparatus, it becomes, however,
imperative to prevent any traces of lubricant, oil or other
foreign matter, such as dust particles, from entering the
interior of the vessel.
20 ting against a protruding ring 34 of the shaft 1.
When using a gear reducer at the upper end of the
Shaft 1 has a threaded upper end 31. A nut 28 having
agitator shaft, it is almost impossible to avoid that 00
a protecting and depending ?ange 26 engages the threaded
casionally small amounts of lubricant oil drip off. Since
end 31 and provides for a solid connection between shaft
the apparatus cannot be watched constantly, it cannot be
1 and bushing 2 and retains bushing 3 in position. A
avoided that at least some foreign matter, or in particular 25 cover nut or cap 29 serves as a locknut and as a seal for
lubricating oil, seeps or oozes out and mixes with the
the uppermost end of hollow shaft 1. A bushing 32 is
contents of the vessel.
pressed into the upper end 31 of the hollow shaft, against
For agitating sensitive substances, for example, foods,
an inner shoulder thereof, a notch 32a being provided
the agitator shaft- has to be rotated very slowly so that
in bushing 32 for holding the shaft 1 during the assembly
a gear reduction is necessary if standard electric motors 30 of the drive parts. A set screw 5 is arranged to extend
are used. These circumstances would preclude the at
through the cone-shaped bushing assembly 4, 33 for
tachment of the drive directly on and above the agitator
shaft; however, it is very desirable to arrange the com
plete drive on the cover of the housing or vessel of the
securing the aforesaid drive parts in assembled relation
to shaft 1 so that shaft 1 and all parts thereon are re
turned to their dynamically balanced condition, when
35 ever the shaft has been taken off or was removed for any
The present invention has therefore as one of its objects
reason of repair or the like.
v mixing apparatus.
to provide means completely overcoming the aforesaid
and other di?iculties.
Bushing 2 has an enlargement or central ?ange portion
6 and a threaded upper end 7 and a threaded lower end
:It is a further object of this invention to provide means
8. In the center ?ange portion 6 there is located a key
contriving electric drive means for directly imparting 40 13 which engages a keyway 12 in the hub 11 of the rotor
movement to an agitator shaft or the like at very low
generally designated 35 of the electric motor. An upper
speed without the intermediary of speed reducing means.
nut 9 and a lower nut 10 secure hub 11 to the bushing 2
Another object of the invention is to provide means
in axial direction.
contributing to the disposition of an electric drive motor
The rotor 35 is composed of a ring-shaped supporting
directly on top of the cover of the vessel or housing in
plate 14, welded to bushing 11 and stiffened by a plurality
which the agitator blades or paddles are rotated.
of triangular reinforcing plates 15. Assembled with
Furthermore, it is an object of this invention to provide
plate 14, by means of a lower ring-shaped counterplate
vertical electrical drive means for agitators or the like,
having main bearing means remote from the agitator shaft
'25 and by a plurality of bolts 16', is the outer race 24 of
a ball bearing 23. Rotor plates 17 are secured in their
in order to prevent lubricants or'like foreign matter from 50 proper place on the periphery of rotor 35‘ by the same
getting‘ into the substances under treatment or to be
bolts 16.
The inner race 22 of the ball bearing 23 is mounted
A further ‘object of the invention is to provide rigid
inside the inner ?ange 20 of a U-shaped channel section
mounting meansforan electric drive for preventing vi
composed of outer ?ange 21 and inner ?ange 20 welded to
bration during slow speed operation of the electric motor. 55 ring-shaped bottom plate 19. Inside the outer ?ange 21
Another object of the invention is to provide means
and arranged opposite the rotor plates 17 are fastened
arranging the drive means for an agitator or like apparatus
a corresponding number of core plates 27, constituting
so that the agitator or blade shaft may be readily and
the stator 36 of the electric motor.
easily manipulated for withdrawal from the interior of
In order to obtain a very low number of revolutions
the vessel.
per minute of the rotor, e.g., approximately 100 revolu!
Still another object of this invention is to provide means
tions per minute-under normal A.C. poly-phase frequen
affording a direct and compact drive for the agitator and
cies and voltages, the electric motor composed of rotor
like apparatus, whereby the number of operable parts is
35 and stator 36 possesses, besides a large number of
greatly reduced or simpli?ed.
poles on account of its large diameter and reduced axial
The invention consists in such novel features, arrange
length, so-called fractional windings, in which the num
ments and combinations of parts as may be shown and
ber of slots per pole and phase is not an integer.
described in connection with the apparatus herein dis
However, such windings generate strong unsymmetrical
closed by way of example only and as illustrative of a pre
forces which result in a rotating power vector. This
ferred embodiment.
rotating mechanical force is very great so that the ring
Objects and advantages of the invention will be set 70 shaped bottom plate 19 has a plurality of threaded holes
forth in part hereinafter and in part will be obvious here
18 for safely securing structure 19-20-21 to the cover
from or may be learned by practicing the invention, the
of the agitator vessel or the like (cover and agitator ves
vibrations of the .drive.
While the invention has been described and illustrated
nular stator mounted on the inner surface of said outer
?ange intermediate the axial extent thereof; a rotor shaft
coaxial with said stator support; the inner surface of said
with respect to a certain ‘particular preferred example
which gives satisfactory results, it will be understood by
shaft; a rotor secured to said shaft and extending over
selIbein-g omitted for the sake of clarity), preventing any
inner ?ange being spaced substantially radially from said
the open side of said channel cross-section, said rotor
those skilled in the art after understanding the principle
including pole face means extending within said channel
of the invention, that various other changes and modi?
cross-section and spaced radially from the inner surface
cations may be made without departing from the spirit
of said stator to form an air gap therewith; and an anti
and scope of the invention and it is intended therefore
in the appended claims to cover all such changes and 10 friction bearing for rotatably supporting said rotor on
said stator support and including an outer raceway se
cured to said rotor radially inwardly of said pole faced
Having thus described the invention, what is claimed
forming means and within said channel cross~section, an
inner raceway secured to the outer surface of said inner
?ange, and anti-friction elements movable in said race
as new and desired to be secured by Letters Patent is:
1. A polyphase electric motor for directly driving an
agitator at a very low angular velocity, said motor com
prising, in combination, an annular stator support hav
ing a channel cross-section including an annular base
6-. An electric motor as claimed in claim 5, in which
said rotor includes a substantially ?at annular plate ex
tending over the open end of said channel cross-section
and a pair of substantially cylindrical radially spaced
coaxial inner and outer ?anges, of substantially equal
axial extent, normal to the respective inner and outer 20 and supporting said pole face forming means and said
outer raceway; the outer diameter of said substantially
peripheries of the base and extending in the same axial
?at annular ‘plate being less than the outer diameter of
direction from the latter; an annular stator mounted on
said rotor support and greater than the ‘inner diameter
the inner surface of said outer ?ange; a rotor operatively
thereof; the inner diameter of said substantially ?at an
associated with said stator and including a substantially
nular plate being substantially .‘less than the inner di
?at annular plate extending at least partially over the
ameter of said inner ?ange; the ‘inner periphery of said
open side of said stator support coaxially with said stator
substantially ?at annular plate being drivingly connected
and having an inner diameter not exceeding the inner
to said shaft; whereby the inner surface of said inner
diameter of said inner flange, and constructed and ar
?ange is spaced a substantial radial distance from said
ranged for securement of its inner periphery to an agi
tator drive shaft, and rotor elements secured to said
7. An electric motor as claimed in .claim 6, in which
annular plate adjacent the outer periphery thereof and
said rotor includes a second substantially ?at annular
disposed within said channel cross-section in radially
plate spaced axially from said ?rst mentioned substan
spaced relation to said annular stator; and an anti-friction
tially ?at annular plate and having an outer diameter
bearing for rotatably supporting said rotor on said stator
equal to that of the latter and an inner diameter some
support and including an outer raceway secured to said
what in excess of the outer diameter of said inner ?ange;
annular plate, an inner raceway secured to the outer sur
said pole face forming means and said anti-friction hear
face of said inner ?ange, and anti-friction elements mov
ing being disposed axially between said ?rst and second
able in said raceways.
mentioned substantially ?at annular plates; and means
2. A polyphase electric motor, as claimed in claim 1,
in which said rotor elements comprise rotor plates; and 40 securing said second-mentioned substantially flat annular
plate to said ?rst-mentioned substantially ?at annular plate
means conjointly securing said rotor plates and said outer
to maintain said pole faced forming means and said outer
raceway to said substantially ?at annular plate.
raceway ?xed to said ?rst-mentioned substantially ?at
3. A polyphase electric motor, as claimed in claim 1,
annular plate.
including an agitator drive shaft; a bushing on said drive
8. An electric motor as claimed in claim 5, said rotor
shaft; and means detachably securing said bushing on 45
including a hub keyed to said shaft; and removable
said drive shaft; the inner periphery of said substantially
bushings mounted on said shaft and cooperable with said
?at annular plate being ?xedly connected with said bush
hub to ?x the latter against axial movement relative to
ing for conjoint rotation therewith.
said shaft.
4. A polyphase electric motor, as claimed in claim 3,
including a hub rigidly connected to the inner periphery
References Cited in the ?le of this patent
.of said substantially ?at annular plate and embracing
said bushing; and means securing said hub against angular
and axial movement relative to said bushing.
5. A polyphase electric motor, comprising, in combi
nation, an annular stator support having a channel cross’
section including an annular base and a pair of substan
tially cylindrical radially spaced coxial inner and outer
?anges, of substantially equal axial extent, normal to the
respective inner and outer peripheries of the base and
extending in the same axial direction therefrom; an an
Mueller ______________ ._ July 20, 1915
Burke ________________ __ July 11, 1922
Reist ________________ __ June 2,
Brainard ____________ __ July 12,
Hill ________________ __ May 2,
Aske ________________ __ Oct. 5,
Beach ____ __,_, _______ __ Oct. 21, 1958
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