Centrifuge and method for sensing imbalances in the centrifuge

A method for detecting imbalances in a centrifuge, said centrifuge (10), comprising:

• a rotor (12);
• a drive shaft (14);
• said rotor (12) is mounted on said drive shaft;
• a motor (18);
• said motor drives drive shaft and said rotor (12);
• a supporting unit (30) having damping elements (36);
• each of said damping elements includes a spring axis (36a);
• said supporting unit (30) supports a rotational unit (19);
• said rotational unit comprises said motor (18) together with said drive shaft (14) and said rotor (12);
• a sensor unit (82, 84) for detecting the speed of said drive shaft and said rotor;
• a distance sensor (80) for detecting imbalances of said rotational unit (19);
• said rotational unit (19) rotates around an axis of rotation (14a) at a rotational speed;
• an acceleration sensor (88) for detecting imbalances of said rotational unit (19);
• a control and evaluation unit (90) which evaluates data of said sensors (80, 82, 88);
• said distance sensor (80) includes a sensor head (80a) and a metal head aligned along an operative axis (36b);
• said distance sensor (80) detects changes in distance between said sensor head (80a) and said metal head along said operative axis (36b);
• said operative axis (36b) is aligned relative to said axis of rotation (14a) in such a way that—at least in a projection onto a plane which is parallel to said operative axis (36b) and extends through said axis of rotation (14a)—said operative axis (36b) and said axis of rotation (14a) define an angle between them which is less than 90°, including 0°, comprising the steps of:
• measured values of said sensors and said sensor unit are determined as a function of the continuous rotation of said rotor:
• said measured values are used to form an average value which is compared with the corresponding value of a known performance characteristic of said centrifuge, and,
• further measures being initiated when an average value is detected that is above said known performance characteristic of said centrifuge,
• said further measures comprise switching off said motor of said rotational unit, reducing the rotational speed of said rotor, activating said acoustic and/or optical signals and/or outputting information on a display unit.