For the operation of cars and motorcycles filters are essential, they protect e.g. the engine from contamination.
The filters can be distinguished according to their mode of action and according to the medium to be filtered.
The quality feature of good filters is a high filter performance with the lowest possible backpressure.
Long service life before a filter change are desired.
The air filter has the task to clean the intake air of the engine.
Without a filter, the smallest particulate matter in the intake air together with the engine oil would form a grinding mass that would cause heavy wear on the pistons, cylinders and valve guides.
Frequently, dry air filters are used.
The air flows through the filter elements.
The possible duration of use depends on the dirt load of the air and the size of the paper surface.
This filter type consists of a ring-cylindrical or rectangular-flat construction.
The zigzag folded paper-like fabric, as a filter element, enlarges the filter surface.
This reduces the flow resistance for the intake air and increases the service life.
With the ring filters, the dirty air outside the cylinder is cleaned by the filter and then the clean air inside the ring filter cylinder is forwarded to the engine.
Flat air filters are another common variant of air filter types.
This filter is fixed in the air filter box in a frame.
The air flow is sucked through the zigzag folded fabric and thereby cleaned.
Over time, the strainer becomes dirty and the flow resistance increases.
Therefore they have to be changed regularly.
Power losses and faulty engine combustion threaten, because not enough air can be sucked.
These air filter cartridges are used only once and should be disposed of after use.
Advantage of this dry air filter is the simple and inexpensive production.
Foam dry filter
Foam layers are used in this type of filter instead of the folded paper.
Advantages of this construction of the filter is the higher air passage and the cleaning possibility, which allows a longer service life.
The lower filter effect compared to the paper filter is compensated by thicker foam layers.
The filtered dirt can not be completely removed by cleaning and the filter is becoming more and more and must be replaced at some point.
Also, the foam is not durable.
The filter elements dissolve after a certain time, which also requires a replacement.
Replacement air filters are available for many car and motorcycle models to replace the original air filters.
The manufacturers advertise with up to 100 000 km without cleaning for these continuous air filters.
After cleaning and new oiling these can be used again.
The structure of these filters is realized with oiled cotton.
For carburetor engines, adjust the carburetor's carburetor settings by increasing the airflow through the air cleaner.
When injecting with air quantity and mass meters, manual readjustment is not required.
Mode of action of filters:
Contaminants are retained in the filters by smaller mesh sizes than the size of the contaminant particles. Screen or fiber filters are the most common filter types and inexpensive to manufacture.
A filter constructed by oil-coated metal mesh realizes the filtering of the air flowing through.
The impurities are filtered out by adhering to the oil film.
This type of filter is maintenance-intensive by regularly renewing the oil film and has been used on older motorcycle and moped models.
Magnetic filters are mostly used for supporting filtering.
Ferrous impurities are thereby removed.
Magnetic filtering is used for oil and hydraulic filters.
By rotating air, the impurities are pressed by the centrifugal force to the edge of the filter and deposited there.
This type of filter is easy to clean but expensive to set up.
Other filter types are e.g. Cyclone filter, centrifugal separator, liquid filter, oil bath air filter, oil-soaked filter,