The diesel filter is the core protective component of the fuel supply system of diesel engines, known as the "fuel purification guardian" of diesel engines, which directly determines the operational stability and service life of the engine. Compared to gasoline engines, diesel engines require extremely high fuel cleanliness. The working pressure of high-pressure common rail diesel engines can reach 2000 bar, and even small impurities can cause irreversible damage to precision components. The core function of diesel filters is to thoroughly purify diesel, intercept impurities, separate moisture, and provide clean fuel for the engine.

The filtration work of diesel filters mainly relies on specialized filtration media. Currently, mainstream filter elements use microporous composite filter paper and polymer filter materials, and some high-end models are equipped with fiberglass materials. Its filtration mechanism is divided into three functions: physical interception, adsorption filtration, and oil-water separation. Firstly, when diesel passes through the filter element, the tiny pores of the filter paper will accurately intercept solid impurities such as rust, sediment, gum, and metal debris in the diesel. Depending on the level of coarse and fine filter layers, it can intercept fine particles of 3-25 microns, preventing impurities from entering precision components such as high-pressure fuel pumps and injectors. Secondly, the special fiber structure of the filter material can adsorb viscous impurities such as gum and asphaltene in diesel, avoiding impurities from adhering to the inside of the oil circuit and causing blockage.

Oil water separation is a key core function of diesel filters. Diesel fuel is prone to water contamination during storage, transportation, and refueling, which not only prevents combustion but also severely corrodes engine precision components and reduces fuel atomization efficiency. The diesel coarse filter is equipped with a dedicated hydrophobic structure and a water collection cup, which uses the principle of oil-water density difference to completely separate free water and emulsified water in diesel. The accumulated water settles in the water collection cup and is regularly discharged through a drain valve.

The entire filtration system adopts a graded filtration mode. Diesel is first purified through coarse filtration to remove large particle impurities and most of the water, and then deeply filtered through fine filtration to remove small impurities. Finally, clean fuel is delivered to the engine combustion chamber. A complete filtering process can effectively protect core components such as high-pressure oil pumps, fuel injectors, cylinder pistons, etc., reduce component wear, jamming, corrosion and other problems, ensure full combustion of fuel, improve engine power performance, reduce fuel consumption and exhaust emissions, and is the basic guarantee for the long-term stable operation of diesel engines.