Pumps – Motor driven – Electric or magnetic motor
Reexamination Certificate
1999-11-18
2001-09-25
Freay, Charles G. (Department: 3746)
Pumps
Motor driven
Electric or magnetic motor
C417S423700
Reexamination Certificate
active
06293773
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a corrosion-resistant sleeve for magnetic rotors of pumps, in particular for plastic-encapsulated magnetic rotors in centrifugal pumps, which effectively protects the rotors of laboratory centrifugal pumps from corrosion and premature wear.
BACKGROUND OF THE INVENTION
The known, commercially available laboratory centrifugal pumps are typically fitted with plastic-encapsulated magnetic rotors. The plastic covers of such rotors usually have a layer thickness of approximately 1 to 2 mm and do not protect the magnet of the rotor from corrosive substances which diffuse in (delivery medium).
The penetration of delivery medium leads to considerable corrosion to the rotor magnet. The expansion of the magnets which is associated with the corrosion in turn leads to the formation of cracks in the protective plastic cover and thus to an increase in the rotor diameter.
Consequently, the initial result is contamination of the deliver) medium, and the ultimate result is that the rotor becomes blocked, leading to total failure of the pump. Depending on the type and concentration of the constituents which attack the protective plastic cover of the magnetic rotor, changes in the rotor are visible even after a few days or weeks.
SUMMARY OF THE INVENTION
The object of the invention is to develop effective protection for magnetic rotors which substantially prolongs the service life of the rotors, and therefore also of the pumps which contain magnetic rotors.
The object of the invention is achieved by the fact that the magnetic rotor is covered with a thin, corrosion-stable, tightly fitting metal sleeve in the area of the magnets.
The subject matter of the present invention is a corrosion-resistant sleeve for magnetic rotors, in particular for plastic-encapsulated magnetic rotors in centrifugal pumps, which tightly surrounds the plastic-covered rotor and seals it off from the chamber containing the delivery medium.
REFERENCES:
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patent: 4850818 (1989-07-01), Kotera
patent: 5017102 (1991-05-01), Shimaguchi et al.
patent: 5129795 (1992-07-01), Hyland
patent: 5334004 (1994-08-01), Lefevre et al.
patent: 5580216 (1996-12-01), Munsch
patent: 3413930 (1985-10-01), None
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patent: 3545713 (1990-02-01), None
patent: 2672344 (1992-08-01), None
Doberstein Helge
Kramer Jurgen
Bayer Aktiengesellschaft
Cheung Noland J.
Freay Charles G.
Gil Joseph C.
Gray Michael K.
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