PROCESS AND DEVICE FOR FLOW CONTROL OF AN ELECTRICAL MOTOR FAN

摘要

A method and configuration from maintaining a constant of air to a protective helmet (4) from a fan (3) in a battery powered fresh air unit. The fan (3) is a radial fan with a filter (5) positioned on the suction side of the fan and is operated by a brushless continuos current motor (2). With the aid of signals from postion sensors (30) in the motor (2), a cotrol unit (12) can determine the speed of the fan (3). The control unit also dectects the motor's power consumption and compares this and the speed with a characteristic curve for the motor (2) for a given flow from the fan, which is stored in a memory (14). In the event of any deviation, the control unit (12) regulates a change of the voltage supply to the motor (2) so that the deviation is reduced. In theis waz the flow is maintained constant at the desired, adjustable levle independent of the blocking and battery voltage of the filter (5). The control unit (12) emits signals (qs), Vs to a warning indicator light and buzzer (40, 42) in an alarm unit (38) in the fresch aur unit if the battery voltage falls below a predetermined minimum safety level.