Safety circuit for engine-independent vehicle heaters

摘要

The safety circuit for engine-independent vehicle heaters serves as additional safety against cases of overheating if separate drives are used for feeding combustion air and conducting away heat. With this safety circuit, operational safety is to be increased. It is to be possible to switch on the heat-conducting drive in the starting phase with a time delay with respect to the ignition device, fuel feed and combustion air feed and the fuel feed is to be disabled if no current flows when a voltage is applied. The object is achieved in that a coil with magnetic core is inserted in the circuit of the motor serving to conduct away heat, the field lines of which coil are evaluated by a Hall circuit. The output of the Hall circuit is connected via a diode to the switching line of the engine to be monitored, to the control component of the heating device and via a resistor to the stabilised voltage. <IMAGE>