A method of controlling an electric motor with oscillating output shaft particularly for automobile wiper systems, and the arrangement of that electric motor

The output shaft (8) of the electric motor swings first to one end stop, the direction of the rotation of the motor then changes, whereupon the output shaft (8) is returned at a constant speed to the opposite stop, whilst in the same pre-selected constant time intervals its angular position is measured between the two stops. Taking into account the size of the angle between the two stops, the measurement data on the angular position are converted into angle increments in individual, measured, constant time intervals and a calibration curve is thus made of the specific sensor used for measuring the angular position of the output shaft (8) of the motor. From this calibration curve is then determined the absolute value of the output variable of the sensor used, for any angle of the actual position of the output shaft (8) of the motor, whereupon the required time behaviour of the angular position of the electric motor is determined, and then continuously at certain time intervals depending upon the required number of swings per time unit, data on the angular position of the output shaft (8) of the motor are taken. In accordance with the calibration curve the data are converted into the actual angular value of the position of the output shaft (8), and if a deviation is discovered from the required time behaviour at any given moment, a correction is made in the speed of the electric motor depending upon the direction and magnitude of this deviation. The stator casing (3) of the motor is part of its gear box (for example its extension) and is in the shape of an open cylinder, into which is inserted the lid (4) of the stator with a bearing (5) for positioning one end of the shaft (1). Into the casing (3) is inserted a magnetic circuit (6) consisting of a steel pipe with inserted permanent magnets (7) or of a stator lid (4), whilst onto the output shaft (8) of the motor there is fixed a worm wheel to which permanent magnets with pole extensions are attached, between which, in the operating position, a Hall sensor of the angular position of the output shaft (8) of the motor is inserted.