What principle does the operation of filter equipment depend on?

The production of filter equipment has attracted much attention. It not only improves people's life, but also brings great convenience to people's life. It has a wide range of uses. It is divided into three categories. What kind of principles are used to operate it?
All of the filter equipment is divided into three types, namely oil filter, air filter and fuel filter. Air filter equipment is located in the intake system of the engine, which is composed of one or several components of clean air filter. Its main function is to filter out the harmful impurities in the air that will enter the cylinder, so as to reduce the early wear between the cylinder, piston, piston ring and valve. The oil filter equipment is located in the engine lubrication system. Upstream of it is the oil pump, and downstream is the parts of the engine that need to be lubricated. The function of the oil filter equipment is to filter and remove the harmful impurities in the oil from the oil bottom, so as to bring clean oil to the crankshaft, connecting rod, piston ring and other moving parts, to play the role of lubrication, cooling and cleaning, so as to prolong the service life of these parts. After the fuel filter equipment, this is how widely used. It is installed on the pipeline between the fuel pump and the oil inlet of the throttle body in series. Its function is to remove the iron oxide, dust and other solid impurities contained in the fuel, so as to prevent the blockage of the fuel system, reduce the degree of mechanical wear and prolong the service life.