Cold start
In the case of an internal combustion engine, a cold start refers to the start of operation without cooling water and / or oil having been preheated beforehand and without pressure having previously built up in the lubricating oil circuit or without sufficient oil reserves in the bearing points. In the other case one speaks of a warm start ; in special cases, for example when the engine was switched off after driving with a high load, even from a hot start .
Engine load
A cold start places a particular strain on an internal combustion engine. The rapid but uneven heating of the individual components results in increased wear. Plain bearings run dry. In Otto engines, part of the fuel condenses in the intake tract or in the cylinder, so that more fuel has to be added, which can lead to oil dilution . With diesel engines , depending on the outside temperature, a separate cold start device is required, which is usually equipped with glow plugs . The engine cannot be fully loaded after a cold start, which must be taken into account during the warm-up phase in order to avoid damage. Reaching the optimum operating temperature as quickly as possible through engine measures, additional heaters or an appropriate load on the engine minimizes pollutant emissions, wear and tear and specific consumption.
The targeted loading of an engine can, for. B. can be brought about by immediately starting the journey for cars / commercial vehicles without long idle phases. Immediate peak loads are just as unfavorable in terms of uniform heating of the components as longer, load-free running with low efficiency and generally significantly poorer emissions.
Cold starts also reduce the service life of the timing belt .
Precautions
Engines that have to run immediately at full load ( e.g. emergency power generators and rescue vehicles ) are therefore always kept preheated and equipped with an electric lubricating oil pump. Also, some so-called heavy stationary units as well as some drives of locomotives and ships are not designed for cold starts and are always started preheated.
The pollutant emissions of an internal combustion engine are particularly high until the operating temperature is reached. A cold run controller can ensure complete oxidation of the fuel by supplying additional air. In the case of gasoline engines in vehicles with a regulated catalytic converter, a secondary air pump can also achieve a significant improvement in emissions during a cold start until the catalytic converter is heated to operating temperature .
literature
- Peter A. Wellers, Hermann Strobel, Erich Auch-Schwelk: Vehicle technology expertise. 5th edition, Holland + Josenhans Verlag, Stuttgart, 1997, ISBN 3-7782-3520-6 .
- Jan Drummans: The car and its technology. 1st edition, Motorbuchverlag, Stuttgart, 1992, ISBN 3-613-01288-X .