The invention is directed to an alternator with an added ventilator, particularly a three-phase alternator for motor vehicles in which the air flow of the added ventilator serves to cool the alternator, and wherein the added ventilator is supplied with voltage by the alternator.
In internal combustion engines which are operated over a very great speed range and in which high demands are made on alternator outputs, it must be ensured for reasons relating to temperature that the alternator is cooled with fresh air by means of an additional ventilator. This fresh air can be supplied e.g. via a hose line from an area located outside the engine space.
Alternators with external ventilation, in which the alternator is additionally cooled by means of a fan, are already known in principle. Thus, for example, an externally ventilated three-phase alternator is known from DE-OS 32 31 152 in which the fan is driven by means of a three-phase asynchronous motor whose squirrel-cage rotor is securely coupled with the fan. In so doing, the stationary windings of the asynchronous motor are connected, via a switch, to the a.c. windings of the alternator for the power supply. However, a monitoring of the functioning of the asynchronous motor, and accordingly of the fan, is not provided; the alternator can accordingly be destroyed by thermal overloading in the event that the fan does not start as desired.