Agitating – Stirrer within stationary mixing chamber – Pump type
Patent
1997-02-11
2000-09-26
Cooley, Charles E.
Agitating
Stirrer within stationary mixing chamber
Pump type
277572, 4151743, 416146A, 416174, 416247A, B01F 1500
Patent
active
061234486
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention concerns an agitator for the mixing and/or conveying of aggressive liquids and/or liquids containing solids or fibers, consisting of a drive motor which is encapsulated by a housing and seals so as to be liquid-tight, on the central drive shaft of which a propeller boss is located, the largest diameter of which is roughly equal to the diameter of the housing, where an elastic deflector ring which overlaps the gap between propeller boss and housing is provided on the housing.
This class of drive, as known from U.S. Pat. No. 5,007,867 or EP-A-0.252.037, for example, is also used as agitators, particularly in sewage engineering, for mixing liquids containing solids or fibers, in order to prevent the solids settling on the bottom of a tank or container, for example. To this end, the agitators are immersed in the liquid to be mixed and fastened below the liquid level. The liquids to be mixed can, to a limited extent, also be conveyed with the help of the agitators if an appropriate piece of piping is installed upstream of the propeller.
The usually dome-shaped design of the propeller boss, the largest diameter of which is roughly equal to the diameter of the housing, is intended to achieve the most favorable flow conditions possible, in order to keep the formation of eddies relatively low and achieve an optimum mixing effect at a high level of efficiency.
According to the prior art, in order to avoid solid or fibrous materials being drawn into the gap between the housing and the propeller boss in the known drives or agitators, a deflector ring is placed over this gap, but does not lie against the propeller boss to form a seal.
In addition to the penetration of solid materials, there is also the problem, when handling aggressive liquids, that acids or alkalis with relatively high flow rates pass through the gap into the internal cavity of the propeller boss and act on the drive shaft or the floating ring seals surrounding the drive shaft, which can cause damage or leaks. In order to prevent the penetration of such aggressive liquids, attempts have thus been made to build up excess pressure with the help of a rinsing liquid which is fed into the internal cavity of the propeller boss so that the aggressive liquids can no longer enter or are diluted. However, as this liquid escapes through the gap, relatively large quantities of rinsing liquid must be used.
SUMMARY OF THE INVENTION
The invention is based on the task of creating an agitator which prevents penetration of the gap between housing and propeller boss by solid or fibrous materials in a simple manner or minimises the necessary quantity of rinsing liquid when using a rinsing device.
According to the invention, this task is solved by the area of the deflector ring which overlaps the propeller boss being designed as an all-round tongue which lies on the propeller boss or displaying an all-round sealing lip which lies on the propeller boss.
The elastic deflector ring is fastened on the housing and seals this by overlapping it with one lateral area, while the opposite lateral area lies on the propeller boss to form a seal, meaning that the gap between housing and propeller boss is effectively covered in a simple manner. The elastic design even ensures a deflecting effect as regards the gap if the propeller boss displays certain tolerances or runs eccentrically.
In order to ensure that the deflector ring sits tightly on the housing, it is preferably provided with internal, all-round grooves or projections which can be pressed into corresponding projections or grooves on the head of the housing. In this way, worn deflector rings can be very easily replaced, as they can be expanded slightly owing to their elastic design and, for example, pushed backwards over the housing and removed or fitted.
The outer peripheral surface of the deflector ring is preferably designed in the manner of an aerofoil so that the flow in the vicinity of the deflector ring caused by the propeller effect is accelerated towards the propeller and
REFERENCES:
patent: 4021143 (1977-05-01), May
patent: 4911663 (1990-03-01), Meier
patent: 5490731 (1996-02-01), Scharf et al.
Becker Klaus
Dirla Manfred
Fassbender Hans-Peter
Wasser Wilfried
ABS Pump Cent4r GmbH
Cooley Charles E.
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