Pumps – Motor driven – Electric or magnetic motor
Patent
1994-12-09
1997-06-24
Freay, Charles G.
Pumps
Motor driven
Electric or magnetic motor
417351, 41742314, 310 86, 310156, F04B 3504
Patent
active
056412762
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electric pump comprising an impeller coupled via a shaft to at least one permanent magnet rotor of an electric motor, and a hermetically sealed housing in which the shaft is supported and which has as sole openings the delivery side and suction side connections for the material to be pumped.
2. Background Information
The present invention specifically relates to powerful pumps having an electrical power in the range of 10 kW and more. When installing such powerful pumps in a piping system, the drive for the pump unit proper is provided in the form of a motor flange-mounted to the outside of the pump housing.
Pump aggregates with a power in the above-indicated range are heavy and bulky. They require specific support on a foundation. Direct, freely supported integration in the piping system is not possible with the known pumps.
There are specific legal regulations concerning the design of pumps, in particular pumps used for environmentally hazardous fluids. It must be ensured that leakage of environmentally hazardous fluids is prevented. This leads to specific problems with respect to the sealing of the shaft passage. In the known pumps, the rotary shaft left the pump housing at at least one location of the housing. This is where special sealing measures must be taken.
There was already suggested an electric pump of the type indicated at the outset, in which measures are taken for preventing that the shaft extends out of the pump housing. To this end, the known electric pump is provided with a housing enclosing the electric motor, the drive shaft and the pump impeller located on the drive shaft. This pump complies with the legal requirements and avoids complex sealing measures; for, as the shaft does not leave the housing at any location, the pumping material has virtually no possibility to get out of the housing.
SUMMARY OF THE INVENTION
It is the object of the invention to make available an electric pump of the type indicated at the outset which may easily be installed in piping systems without any specific supports and which, furthermore, reliably prevents the leakage of pumping material by avoiding shaft passages or lead-outs in the housing.
This object is met in that the rotor is disposed inside the housing and the stator parts of the stator of the electric motor are disposed outside the housing.
The invention starts from the realization that first and above all care must be taken that the shaft driving the pump impeller does not extend out of the housing at any location. While the prior suggestion in this respect provided that the entire electric motor together with shaft and impeller, but without control electronics, were accommodated in the housing, the present invention still takes one step further: of the electric motor, only the permanent magnet rotor is disposed inside the housing, whereas the stator is located outside the housing. This measure yields an even more compact construction of the housing on the one hand and provides more freedom with respect to the stator design on the other hand.
The stator parts of the stator of course must be positioned such that an interaction can take place between stator and rotor. In a specific embodiment, the invention provides that the rotor consists of radially oriented permanent magnet poles of alternating polarity which are distributed across the shaft circumference, and that the stator, in the form of a ferromagnetic ring axially aligned with the rotor and having coil windings, is supported on the outside of the housing wall.
In the simplest configuration, there is provided only one single rotor in conjunction with one single stator. For increasing the driving power, it is also possible to provide several rotors on the drive shaft in axially offset manner, with a corresponding number of stators being then provided outside of the housing.
Of course, an as small as possible gap should be present between the outer circumference of the rotor and the inner circumferen
REFERENCES:
patent: 1973070 (1934-09-01), Hess et al.
patent: 2649048 (1953-08-01), Pezzillo et al.
patent: 4339874 (1982-07-01), McCarty et al.
patent: 4639627 (1987-01-01), Takekoshi et al.
patent: 4877985 (1989-10-01), Byrd et al.
patent: 5044897 (1991-09-01), Dorman
patent: 5349258 (1994-09-01), Leupold et al.
Ehrhart Peter
Heidelberg Gotz
Freay Charles G.
Magnet-Motor Gesellschaft fur magnetmotorische Technik mbH
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