Agitating – Stirrer within stationary mixing chamber – Rotatable stirrer
Patent
1987-01-27
1990-04-17
Hornsby, Harvey C.
Agitating
Stirrer within stationary mixing chamber
Rotatable stirrer
366295, 366296, 366 66, 241 98, 475253, B01F 700
Patent
active
049186655
DESCRIPTION:
BRIEF SUMMARY
The invention relates to mixing apparatus of the kind having two coaxial stirrers and a common motor for driving them.
Apparatus of the general class to which the invention relates is known for example from U.S. Pat. No. 2,209,287. In that apparatus, one stirrer is coupled directly to the drive motor, whilst the other stirrer is driven via the inner gear ring of a planetary gear in which the sun wheel is coupled to the drive shaft and the planet carrier is fixed stationary on the housing of the mixing apparatus. Consequently the two stirrers are driven at a fixed spaced and a constant speed ratio.
The disadvantage of such a construction is that when one stirrer has to overcome a particularly great moment of resistance, and in an extreme case comes to a standstill, the other stirrer is also incapable of exerting a stirring effect.
The object of the invention, therefore, is to provide dual stirrer mixing apparatus wherein the two stirrers operate in an optimum manner even with differing and alternating moments of resistance.
In the mixing apparatus according to the invention the speeds of the stirrers are not fixed in advance but are automatically set as a function of the counter-moment of the stirrers. If the counter-moments (i.e. the moments of resistance exerted on the stirrers by the material to be mixed) alter, then the speeds of the stirrers are also altered so that the stirrer encountering the least resistance rotates at an increased speed that is higher than its initial speed. If in an extreme case one stirrer is brought to a standstill by an unusually great moment of resistance then the other stirrer goes at maximum speed.
If the external diameter and/or the tool cross-section of one stirrer is chosen so as to be greater than the external diameter and/or tool cross-section of the other stirrer, then basically the first stirrer runs more slowly than the second stirrer. Furthermore, the speed of each of the two stirrers is adapted to the moment of resistance in each case.
The mixing tool according to the invention is also distinguished by an optimum mixing effect even with material which is difficult to mix, and also by low energy consumption and compact construction.
The invention is explained in greater detail below with the aid of several embodiments which are illustrated in the drawings wherein;
FIG. 1 shows a partially cut-away overall view of the mixing apparatus according to the invention;
FIG. 2 shows an enlarged sectional view of a detail (corresponding to the section II in FIG. 1) to explain a first embodiment;
FIG. 3 shows a sectional view of a detail similar to that of FIG. 2, but to explain a second embodiment;
FIG. 4 shows a variant (similar to FIG. 2) of a further embodiment;
FIG. 5 shows a partial representation of a further embodiment.
First of all the general construction of the mixing apparatus will be described with the aid of FIG. 1. This mixinng apparatus is built on a stand 1 on which is arranged a pillar or column 2 supporting a mixing vessel 3 which is constructed as a cylindrical vessel with a vertical axis 3a. The base 4 and the peripheral wall 5 of this mixing vessel 3 can be of double-walled construction and can have a heat exchange medium (e.g. cooling medium) flowing through them. A cover 6 closes off the mixing vessel 3 towards the top, whilst a discharge pipe 7 or the like serves for the discharge of the mixed material.
The drive shaft 9 of a planetary gear 10 which will be described in greater detail below is supported and guided in at least one roller bearing 8 inside the support 2. The planetary gear serves for the common rotary drive of a lower stirrer 11 which is arranged near the base inside the mixing vessel 3 and an upper stirrer 12 which is arranged axially spaced above the stirrer 11.
In this embodiment at least two blades 11a having the same cross-section and the same radial length are provided as stirrer tools for the lower stirrer, and at least two blades 12a having the same length and the same cross-section are also provided as stirrer tools for the upper
REFERENCES:
patent: 1425678 (1922-08-01), Newhouse
patent: 2161604 (1939-06-01), Watts
patent: 2182285 (1939-12-01), DeCaria
patent: 2209287 (1940-07-01), Simpson
patent: 2458706 (1949-01-01), Howe
patent: 2846895 (1958-08-01), Severin
patent: 4019722 (1977-04-01), Shohet
patent: 4057226 (1977-11-01), deMos
patent: 4403868 (1983-09-01), Kupka
Hornsby Harvey C.
O'Leary K.
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