Air filters to prevent sand and dirt into the engine air intake system, engine maintenance, cylinder, piston and piston rings, extending the life of the engine. According to the impurities removed, air filters can be divided into three categories: Inertia: rapid changes in air flow direction, was cleared because of dust particles have a greater inertia and larger particles. Oil bath type: before the air enters the filter, turning in air flow through the oil surface, due to inertia and out of the large particles, dust adhesion by oil. Filter type: gas flow microporous filters or narrow filter when twists and turns producing multiple collisions, blocked from the dust or glue on the filter element, which is a main way of filtering, clear the micro dust are the most effective. Air filter for use on modern automobile engine, combines all three filtration methods, formed the integrated air filter. Main performance indicators of dry-type air filter Dry-type air cleaner refers to micro porous fiber filter paper filter, it has a light weight, small size, low cost, easy to manufacture a series of advantages. The main performance indicators are: the rated flow, the coarse filter efficiency and the filtration efficiency, original resistance, laboratory life, and so on. Rated flow Rated flow rate of the air filter is provided by the host plant, technicians marked on the pattern of air filter products. At standard atmospheric pressure through the air filter outlet air flow rate, it should be required under the rated power of the engine air supply to match. Unit: m³/hour (m3/h). The nominal air flow rate can be based on the work of the engine volume, speed and air coefficients to determine, it is calculated as follows: Q = 0.5x10-traditional four-stroke engines 3. Vn.N.η.ε Two-stroke engine Q =10-3.Vn.N. η. ε Rough filtration efficiency At nominal air flow rate, coarse filters ability to isolate dust, expressed as a percentage. ηc = (△Mc / Mg ) ×100% In the formula: η c....... filtration efficiency,%; Mg......... Add dust, g Mc....... coarse filter dust collector and dust around the quality increase, g; Coarse filters using inertial or centrifugal device of the part in front of the filter to remove dust. Strainers type: Cap-type strainers, strainers, leaf ring and tangential inlet strainers, Vortex tube coarse strainer. Filter efficiency Dust in the air is the internal combustion engine cylinder liner, piston, piston rings, valve and valve guide as well as other major causes wear of moving parts. Dry-type air filters for the most important task is to ensure adequate protection of internal combustion engines, avoid certain particles of dirt for engine wear. Filtering efficiency is the most important air filter specification, it is the ability to test filtering out specific test dust, expressed as a percentage. The formula is as follows: When weighing the absolute filter method, η = (1-Mj/Mg) x100% When using test method weighing, η = (Ms/Mg + Mc/Mg) x100% The original resistance Assembly the original resistance: when rated air flow when equipped with a new filter Assembly, Assembly air outlet by measuring the static pressure, kPa (mm of water column) that the Pa (mmH2O). Filter the original resistance: the new filter element and resistance measurement tube connects at nominal air flow by measuring the static pressure, and with an ideal nozzle replace the filter after the measured difference between the static pressure, kPa (mm of water column) that the Pa (mmH2O). Jam resistance refers to the end of the air filter Assembly Assembly Assembly of laboratory life-ending resistance, kPa (mm of water column) that the Pa (mmH2O). Jam resistance ended when you arrive, the internal combustion engine will not get enough air supply and exhaust smoke, problems such as lack of motivation. Laboratory life Air filter Assembly laboratory life: at nominal air flow rate, in the prescribed concentration that evenly in a row to join in the Assembly of dust, when the resistance ended when the plug Assembly resistance, to join in the Assembly of dust accumulated time, expressed in hours, h. Single-stage Assembly laboratory life: ≥ 8 h; Multilevel Assembly does not have a swirling pipe strainers laboratory life: ≥ 10 h; Cyclone pipe strainers of multilevel Assembly laboratory life: ≥ 16 h.