Fuel filter
The fuel filter is a component in motor vehicles that removes solid particles from the fuel . It is operated as a main flow filter and is mostly filled with a paper-like material . The installation location is in the fuel line to the engine, a distinction must be made between diesel filters and petrol filters: Diesel filters have a cartridge-like design with one-sided flange, similar to an oil filter . Petrol filters are usually installed "inline" in the suction line to the fuel pump or in the pressure line between the pump and the injection valve; their housing is usually made of plastic or light metal sheet.
The raw fuel
Unfiltered fuel can contain various types of contaminants, for example pieces of paint or dirt that got into the tank during filling, but also rust that has formed due to moisture in the steel tanks. If these substances are not removed before the fuel gets into the engine, premature wear and defects in the fuel pump and the injection system are likely, caused both by clogging of nozzles, but also by the wear-promoting effect of the particles.
Filter maintenance
Fuel filters require regular maintenance. To do this, the filter is normally replaced by disconnecting it from the fuel line and replacing it with a new one, which is usually filled with fuel beforehand in order to enable the engine to start more quickly.
In addition, there are filters that can be cleaned and thus reused.
Failure to maintain a filter can clog it and significantly impede the flow of fuel, resulting in a noticeable decrease in engine performance. In extreme cases, the fuel flow can dry up completely.
In diesel injection systems, the vertically installed filter housings are also used to separate specifically heavier water that collects on the filter base. As part of regular maintenance, any water that may be present can be drained using a frequently rotatable device.
construction
For a long time, single-use, small-volume filters made of transparent plastic were common in motor vehicles with gasoline engines. These had connection nozzles onto which the connection hoses were pushed in the event of a replacement.
Diesel fuel filters are usually large-volume and can-shaped. Filling quantities of 0.5 liters are common. The significantly larger filter surface allows fine-meshed filters that are slowly flowed through. As a result, high separation rates can be achieved and even the finest dirt particles can be retained, which would otherwise wear out the finely machined, high-precision injection pumps and also the injection injectors prematurely and thus render them unusable.
In addition, the vertically installed filter housings are used to separate specifically heavier water that has been brought in through condensation of air humidity or poor fuel quality. This water collects on the filter base. As part of regular maintenance, any water that may be present can be drained using a frequently rotatable device. When using the highly hygroscopic biodiesel , shortened maintenance intervals may be necessary.
In addition, diesel filters can also have sensors that can signal the need for maintenance. Some diesel filters can be heated so that the paraffin, which may flocculate at low temperatures, does not clog the filter. Simple systems use the heated, excess fuel from the return line of the injection pump, previously also from the injection valves, which is fed back in via a thermal valve upstream of the filter at low inlet temperatures.
history
In the past, the fuel was sometimes treated with filter systems that were not integrated in the vehicle, as this photo from 1951 shows.
literature
- Hans Jörg Leyhausen: The master craftsman's examination in the automotive trade part 1. 12 edition, Vogel Buchverlag, Würzburg, 1991, ISBN 3-8023-0857-3
- Max Bohner, Richard Fischer, Rolf Gscheidle: Expertise in automotive technology. 27th edition, Verlag Europa-Lehrmittel, Haan-Gruiten, 2001, ISBN 3-8085-2067-1
Individual evidence
- ↑ Picture of a disposable filter made of clear plastic
