Magnetic-drive centrifugal pump

Claim 1

A magnetic-drive centrifugal pump including a driving motor, pump means having a rotor and a magnetic coupling consisting of a driving magnet provided on a magnet holder connected to said driving motor and an impeller magnet provided in said rotor to be magnetically coupled to said driving magnet, wherein said pump means further comprises: a pump shaft; an impeller; a rotor sleeve portion between the impeller and a main portion of the rotor and having the impeller connected thereto, said sleeve portion having an outer diameter smaller than an outer diameter of the main protion of the rotor, said impeller, said main portion of said rotor and said sleeve portion being rotatably mounted on said pump shaft; a pump casing consisting of a front casing surrounding said impeller and a rear casing surrounding a rear surface of the impeller and said sleeve portion and main portion of said rotor; said rear casing having at a location opposite said sleeve portion a first inner diameter which is large enough to enable an outer circumference of said main portion of said rotor to slide therein, and at a location opposite said main portion of said rotor a second inner diameter larger than said first inner diameter; and one end of said pump shaft being journaled in a boss having ribs provided in an inlet of said front casing, and the other end of said pump shaft being journaled in a rear wall of said rear casing; whereby the rotor is adequately supported by the rear casing during disassembly so as to avoid application of off-set stresses to the pump shaft and inner surfaces of the rear casing.