English 简体中文

空气质量知识

For automobile air filters, owners must understand these foundations.
Source: | Author:hkw5ff397 | Published time: 2018-09-06 | 224 Views | Share:
A device for removing particulate impurities in air. Piston machinery (internal combustion engine, reciprocating compressor, etc.) when working, if the inhalation of air containing dust and other impurities will aggravate the wear and tear of parts, so it must be equipped with air filter.

The air cleaner consists of two parts: the filter core and the shell. The main requirements of the air filter are high filtration efficiency, low flow resistance and continuous use for a long time.

Main role

Engine in the process of work to absorb a large amount of air, if the air is not filtered, suspended dust in the air is sucked into the cylinder, it will accelerate the wear and tear of the piston group and cylinder. Large particles entering between the piston and cylinder will cause serious "cylinder pulling" phenomenon, which is particularly serious in dry and sandy working environment. The air filter is installed in front of the air pipe to filter out the dust and sand particles in the air and ensure that enough and clean air enters the cylinder.

Among the tens of millions of automobile parts, air filter is a very insignificant part, because it does not directly affect the technical performance of the automobile, but in the actual use of the automobile, air filter has a great impact on the life of the automobile (especially the engine).

On the one hand, if there is no air filter, the engine will inhale a large number of dust, particles of air, resulting in serious wear and tear engine cylinders;

On the other hand, if the filter is not maintained for a long time in use, the filter element of the air filter will be filled with dust in the air, which will not only reduce the filtration capacity, but also hinder the flow of air, resulting in the mixture is too thick and make the engine work abnormally.

Therefore, it is very important to maintain air filters on time.

Air filters usually have two kinds of paper and oil bath. Paper filter has been widely used because of its high efficiency, light weight, low cost and easy maintenance. The filter efficiency of paper filter is over 99.5%, and that of oil bath filter is 95-96% under normal conditions. The air filter widely used on cars is paper filter, and it is also divided into two types: dry and wet. For dry filter, once immersed in oil or water, filter resistance will increase sharply, so do not touch water or oil when cleaning, otherwise you must replace new parts.


When the engine is running, the air intake is intermittent, which causes the air vibration in the air filter housing. If the air pressure fluctuation is too large, it sometimes affects the engine intake. In addition, the intake noise will also be increased. In order to suppress the intake noise, the volume of the air filter shell can be increased, and some of the partitions are arranged in it to reduce the resonance.


The filter elements of air filter are divided into two types: dry filter element and wet filter element. Dry filter element material is filter paper or non-woven fabric. In order to increase the air passing area, most of the filter elements are processed with many small folds. When the filter element is slightly stained, compressed air can be used to clean, when the filter element is seriously stained, the new core should be replaced in time.


The wet filter element is made of spongy polyurethane material. When it is installed, some oil should be dripped and kneaded by hand to absorb foreign bodies in the air. If the filter element is fouled, it can be cleaned with cleaning oil, and the new filter element should be replaced if it is too dirty.

If the blockage of the filter core is serious, the intake resistance will increase and the engine power will decrease. At the same time, because of the increase of air resistance, it will also increase the amount of gasoline sucked in, resulting in excessive concentration of the mixture ratio, thus deteriorating the operation of the engine, increasing fuel consumption, but also easy to produce coke. Normally, habit of checking air filter element regularly should be developed.

Main classification

There are two types of air filters, dry and wet.

A dry air filter is a filter that separates impurities from the air by a dry filter (such as a paper filter). Air filters used for light vehicles (including cars and mini cars) are generally single stage. Its shape is oblate or elliptical and flat. The filter material is filter paper or nonwoven fabric. The end cover of the filter element is metal or polyurethane, and the shell material is metal or plastic. Under rated air volume flow, the original filtration efficiency of the filter element should be no less than 99.5%. Due to the bad working environment, the heavy duty air filter must have a large number of air filters. The first stage is a swirling pre-filter (such as blade ring, swirling pipe, etc.), which is used to remove coarse particles and impurities. The filtration efficiency is more than 80%. The second stage is a microporous paper filter element (commonly known as the main filter element), and the filtration efficiency is more than 99.5%. There is also a safety filter element behind the main filter element, which is used to prevent dust from entering the engine when the main filter element is installed and replaced, or when the main filter element is accidentally damaged. The material of the safety core is mostly nonwovens and filter paper.

Wet air filter includes two kinds of oil immersion and oil bath.

Oil-immersed filter is used to separate impurities from the air by an oil-immersed filter element, which is made of wire fabric and foamed material.

Oil bath is to take in the dust-laden air into the oil pool and remove most of the dust, and then oil mist in the air upward flow through a wire-wound filter element for further filtration, oil droplets and blocked dust returned to the oil pool together. Oil bath air filters are commonly used in agricultural institutions and marine power.

There are 3 ways of air filtration: inertia, filtration and oil bath.

(1) Inertial formula: because the density of impurities is higher than that of air, when impurities rotate or turn sharply with air, the action of centrifugal inertial force can separate impurities from the air stream.

Filter: guided air