The oil filter is located in the engine lubrication system. Its upstream is the oil pump, the downstream is the engine parts that need lubrication. Its function is to filter out the harmful impurities in the oil from the oil pan, and supply clean oil to the crankshaft, connecting rod, camshaft, supercharger, piston ring and other moving pairs to lubricate, cool and clean these parts, so as to prolong the service life of these parts. According to the structure, the oil filters can be divided into replaceable type, spin on type and centrifugal type; according to the arrangement in the system, it can be divided into full flow type, full flow type, and full flow type Split type. The filter materials used in oil filter include filter paper, felt, metal mesh, nonwovens, etc.
Before the 1980s, most of the oil filters used in Chinese engines were replaceable. The filter element and other parts, such as spring and sealing ring, are put into a metal shell, and the shell filter element and a metal filter seat are connected and fixed by a pull rod. It has the advantage of low cost and only needs regular maintenance and replacement of filter element. The disadvantage is that there are too many sealing points, and the replacement of filter element may miss the installation of parts, which is easy to cause loopholes, and the replacement is laborious.
Since the early 1980s, Bengbu General filter factory introduced the first rotary filter production line from Italy in China. Since then, the rotary filter has been gradually approved by domestic main engine manufacturers. This kind of filter is characterized by one check valve, by-pass valve and only one sealing point. The overall replacement greatly improves the sealing performance and is easy to replace. The filter element material mostly adopts imported filter paper, so it has high filtration efficiency, small flow resistance and long service life. At present, all domestic cars use this type of oil filter. Most of the mini cars, large, medium and small buses, light and medium-sized trucks, and some heavy-duty trucks and agricultural vehicles all use spin on oil filters.