Mercedes-Benz Aktiengesellschaft

Friedrich Hase

Roland Klak

Peter Joppig

Friedrich Schmid

Andreas Koppitz

The invention relates to a process and apparatus for heating the intake air in internal-combustion engines by means of a flame starting system with at least one glow plug. The apparatus is controlled in such a manner that the glow plug is continuously preheated during a first time period and is operated in pulses in a following second time period and the glow plug is switched off after a safety time has elapsed. The glow plug is preheated after it has been switched off, taking into account the instantaneous glow plug temperature during the cooling and the voltage available in such a manner that the temperature required for a repeat start is reached within a narrow tolerance band. In the case of a repeat starting operation taking place after the safety time has elapsed, the renewed preheating time for the glow plug is specified in accordance with a value determined from the glow plug temperature and the available voltage, the instantaneous glow plug temperature being determined from the cooling time of the glow plug after it has been switched off.

Process for heating the intake air in internal-combustion engines by

A process and device for heating the intake air in internal-combustion engines by means of a flame starting system is disclosed which contains at least one heater plug and has a control unit which supplies the heater plug with voltage for a specific preheating time. To provide a process, by means of which the preheating temperature of the heater plug necessary for starting is safely reached independently of changing boundary conditions, it is proposed to carry out the following cyclically repeating steps: detection of the voltage available at the output of the control unit, determination of a preheating time, associated with this voltage value, for the heater plug, determination of a step value from the division of a predetermined standard value for the preheating time by the value determined for the preheating time, summing of the individual step values in a memory erased at the commencement of the process, and comparison of the memory content with predetermined standard value and termination of the preheating when the standard value is reached, or return to process step (a) as long as the standard value is not reached.

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Stuttgart, Germany

Friedrich Hase