Abstract: A DC-motor (46) actuates a highly-reduced reduction gear of an actuating drive for a flap or valve in order to regulate a gas or liquid volume flow, particularly for heating/ventilation/climatization, or fire or room protection. Current flow in the stator coils (A, B, C) is commutated in a program-controlled manner without integrated position sensors. Algorithms enable counting rotations of rotor (54) of the DC-motor (46). Problems related to the principle of motor rotation speed at low rpm are prevented. The DC-motor (46) includes a stator (44) having three stator coils (A, B, C) which extend over 3n stator poles (52), and an annular-shaped permanent magnet rotor (54) having 2m permanent magnet segments with alternating polarity (N, S), a coaxial cup-shaped external rotor (110) and a coaxial drive shaft (108), whereby n and m are whole multiplication factor numbers (1, 2, 3, 4) and are different from each other.

Abstract: According to the invention, a DC-motor (46) actuates a highly reduced reduction gear of an actuating drive for a flap or for a valve in order to regulate a gas or liquid volume flow, in particular in the field of heating/ventilation/climatisation, or fire or room protection. The electric flow of current in the stator coils (A, B, C) is commutated in a program-controlled manner without integrated position sensors. The rotations of the rotor (54) of the DC-motor (46) can be counted by means of special algorithms. Problems related to the principle of motor rotation speed of less than approximately 200 rpm are prevented.