Patent · US Expired

Speed setting and control system for universal motors

US4158796A · kind A · utility

6Cited by

6References

16Claims

0Family size

Assignee

Robert Bosch GmbH · DE

Inventors

Wolfgang Kosak · Asperg, DE
Peter Werner · Wiernsheim, DE
Hans Gerber · Burghausen, DE
Ivan Hidveghy · Zuchwil, CH

Key dates

Filing date	May 24, 1978
Grant date	Jun 19, 1979
Priority date	—
Expiry date	May 24, 1998

Classification

Technology area (CPC H)Electricity
CPC primaryH02P25/14
WIPO fieldElectrical machinery, apparatus, energy
WIPO sectorElectrical engineering

Abstract

A universal motor is energized by a speed setting circuit during one half wave and a speed control circuit during the next half wave of each cycle of an AC supply. The speed setting and speed control circuits each have a separate timing circuit including a capacitor. There is thus no residual charge on the capacitor of the speed setting circuit remaining from the operation of the speed control circuit during the preceding half wave. The residual charge prevented the setting of low motor speeds in the known systems. The speed control circuit includes a storage capacitor transformer coupled to the motor so that its initial charge corresponds to the current through the motor during the preceding half wave. The charge is transferred to a second capacitor. When the voltage across the second capacitor reaches a predetermined threshold valve, a switch in the speed control circuit becomes conductive and current flows through the motor.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.