Agitator with adjustable magnetic drive coupling

A mixing apparatus including a container, a magnetically driven agitator, said magnetically driven agitator including a member mounted through a wall of said container, said member including a hollow sleeve inside which is housed a rotor supporting a first magnetic coupling means, a propelling screw disposed around said sleeve, a second magnetic coupling means carried by said screw for driving said propelling screw about an axis of rotation by magnetic force developed between said first and second magnetic coupling means, means for rotating said rotor, and adjustment means for adjusting the position of said rotor parallel to said axis inside said sleeve between a first position where said first and second magnetic coupling means are substantially opposite one another to thereby create a maximum magnetic drive force therebetween so that they cooperate for rotating said propelling screw in rotation and selected second positions wherein said first and second magnetic means are offset with respect to one another to thereby alter the magnetic drive force therebetween.

A method for adjusting the magnetic coupling force between a magnetically driven agitator supported by a member extending through a wall of a container wherein the member includes a hollow sleeve in which is housed a rotor which supports a first magnetic coupling structure which cooperates with a second magnetic coupling structure carried by a mixing device mounted within the container so that the mixing device rotates about an axis of rotation under magnetic force developed between the first and second magnetic coupling structures, the method comprising the steps of:

• adjusting the position of the first magnetic coupling structure by movement along a line parallel to the axis of rotation to a first position in general alignment with respect to said second magnetic coupling structure to thereby create a maximum magnetic driving force between said first and second magnetic coupling structures;
• and selectively adjusting the position of the rotor to a selected one of a plurality of second positions along the line to thereby vary the magnetic driving force between said first and second magnetic coupling structures.