Method and apparatus for operating vacuum cleaner

A method of operating a vacuum cleaner having a filter to collect dusts and a variable speed fan motor to give a suction force to a cleaner, comprising the steps of:

• continuously detecting a rotational speed of said fan motor at predetermined intervals during the cleansing;
• presuming a cleaning surface or an object to be cleaned on the basis of a change in rotational speed within a predetermined sampling time;
• and
• controlling an input of the fan motor along a function table which is selected in accordance with the presumed cleaning surface, said selected function table being corrected in accordance with a choking state of the filter whereby the rotational speed of the motor can be automatically operated in the optimum condition in accordance with the cleaning surface or object being cleaned.

A method of operating a vacuum cleaner having a filter to collect dusts and a fan motor to give a suction force to a cleaner, comprising the steps of:

• detecting an actual rotational speed of said fan motor;
• and
• giving a speed command to the fan motor on the basis of the value of the detected rotational speed in accordance with a cleaning surface or an object to be cleaned and a choking state of said filter,
• wherein said speed command is obtained by the following processes:
• process I . . . a rotational speed N is obtained by calculation;
• process II . . . the maximum rotational speed N.sub.max and the minimum rotational speed N.sub.min are obtained within the sampling time;
• process III . . . the cleaning surface is presumed and the degree of choking state of the filter is obtained on the basis of the maximum and minimum rotational speeds N.sub.max and N.sub.min ;
• and
• Process IV . . . one function table is selected from a plurality of function tables and the speed command N* is output by said selected function table;
• whereby the rotational speed of the motor can be automatically operated in the optimum condition in accordance with the cleaning surface or object being cleaned.