In general, the degree of oil contamination depends on the operating conditions of the engine, as well as its technical condition. An important role is played by the influence of environmental factors. The effect of extracting mechanical particles from automobile oils is unquestionable: a clean product will last longer, but its consumption will be less. In addition, oil filtration can prevent its replacement in the event that the sole purpose is solely the presence of mechanical impurities.
An effective filter for automotive oil must meet the following criteria:
- Have the ability to retain the maximum possible number of foreign bodies present in the oil;
- Have a minimum hydraulic resistance, i.e.
Skip the maximum amount of oil per unit time.
These requirements are to some extent contradictory. Therefore, to meet them, it is necessary that the filter simultaneously has a very high density and a very large surface. A sufficient density will ensure that the maximum amount of contaminant particles is retained, and that the surface has a minimum resistance. But in practice it is not possible to realize such a device, therefore, resort, as a rule, to compromise options, optimal from the point of view of a certain criterion.
Filters used in lubrication systems, according to the degree and fineness of screening, are divided into:
- Coarse filters;
- Fine filters.
The principle of operation and design features of filter elements allow us to distinguish:
- Slot filters. Oil cleaning is carried out at the expense of special plates and gaskets forming slots;
- Volume or depth filters. The required degree of purification is achieved due to the passage of oil through several layers of filtering material;
- Filters of surface type. Devices of this type consist of a filter material with through pores.
Pulp and paper filtering elements are difficult to classify as one class, because they occupy an intermediate position between the surface and volume filters.
In a separate category, the so-called magnetic filters are distinguished, which make it possible to remove metal wear products from the oil. The reason for this was the relative nature of the relation of the principle of their action to the processes occurring during filtration.
