The mushroom head is the air filter element

1. The role of the air filter

The engine must inhale a large amount of air during operation. If the air is not filtered and the dust suspended in the air is sucked into the cylinder, it will accelerate the wear and tear of the piston group and the cylinder. wear and tear. Larger particles entering between the piston and the cylinder will cause serious "cylinder pulling" phenomenon, which is particularly serious in dry and sandy working environments. The air filter is installed in front of the carburetor or intake pipe to filter out dust and sand in the air to ensure that sufficient, clean air enters the cylinder.

2． Types of air filters

According to the filtration principle, air filters can be divided into filter type, centrifugal type, oil bath type, and composite type. At present, the air filters commonly used in engines mainly include inertial oil bath air filters, paper dry air filters, polyurethane filter element air filters, etc. The inertial oil bath air filter has three stages of filtration: inertial filtration, oil bath filtration, and filter filtration. The latter two types of air filters are mainly filtered through element filtration. Inertial oil bath air filters have the advantages of small air intake resistance, adaptability to dusty and sandy working environments, and long service life. They have been used in the engines of many types of cars and tractors in the past. However, this kind of air filter has low filtration efficiency, heavy weight, high cost, and inconvenient maintenance, and has been gradually eliminated in automobile engines. The filter element of the paper dry air filter is made of microporous filter paper treated with resin. The filter paper is porous, loose, folded, has certain mechanical strength and water resistance, and has the characteristics of high filtration efficiency, simple structure, light weight and low cost. With the advantages of low cost and easy maintenance, it is currently the most widely used automotive air filter. Polyurethane filter element The filter element of the air filter is made of soft, porous, spongy polyurethane with strong adsorption capacity. This air filter has the advantages of paper dry air filters, but has low mechanical strength and is not suitable for use in car engines. is more widely used. The disadvantages of the latter two types of air filters are their short service life and unreliable operation in harsh environmental conditions.

Various air filters have their own advantages and disadvantages, but there is inevitably a contradiction between air intake volume and filtration efficiency. With the in-depth research on air filters, the requirements for air filters are becoming higher and higher. In recent years, some new types of air filters have appeared, such as fiber filter air filters, composite filter material air filters, muffler air filters, constant temperature air filters, etc., to meet the needs of engine operation.