Heater for motor vehicles which can be operated on several power settings

摘要

By temperature gradient detection it is determined for the liquid combustion chamber auxiliary heater for motor vehicles, whether e.g. a flame blow-off has taken place, which has to be interpreted as a malfunction and hwich necessitates the discontinuation of fuel supply. Alternatively, it might merely show the switching from a high setting to a low setting. In the latter case a temperature drop to a lower operation temperature occurs also. However, the temperature drop is not as steep as in the case of a flame blow-off. At certain points in time t1 the target temperature for a point in time t2 is calculated by the detected temperature according to a certain algorithm having specific device properties as parameters. At this point in time the calculated target temperature is checked for errors.