Three engine filters, divided into oil filter, fuel filter, air filter. Each filter acts on the intermediate filtration of the engine lubrication system, combustion system and air intake system respectively.

First, oil filter

Oil filter concept
Oil filter, located in the engine lubrication system. The upstream of the filter is the oil pump, and the downstream is the parts that need to be lubricated in the engine. The main function is to filter out the harmful impurities in the oil pan oil, supply the connecting rod, supercharger, piston ring and other accessories with clean oil, play the role of lubrication, cooling, cleaning, and improve the efficiency of the engine.
Oil filter, the filter materials used are filter paper, felt, nonwovens and so on.

Oil filter classification
Oil filter, according to the structure is divided into: interchangeable filter, rotary and centrifugal filter; According to the arrangement in the system can be divided into full-flow filter, shunt filter.
Shunt filter, only filter oil oil supply volume of 5%-10%. Shunt oil filters are fine filters, generally used with full-flow filters.
In general, most engines with small power only use full-flow filters. Diesel engines with large power are mostly used with full-flow and shunt filters.

Oil filter performance parameters
Flow rate, working pressure, filtration accuracy and efficiency, original pressure difference and pressure drop, service life

Second, fuel filter

Concept and classification of fuel filters
Fuel filter, diesel filter, gasoline filter and natural gas filter three categories. The function of the filter is to filter out harmful particles and water in the fuel gas system to protect the oil pump nozzle, piston ring, etc., reduce wear and avoid blockage of the fuel system.

Diesel filter
The structure of the diesel filter is roughly the same as that of the oil filter, and there are two kinds of interchangeable filter and rotary filter. The working pressure and oil temperature resistance of the diesel filter are much lower than that of the oil filter, but the filtration efficiency requirements are much higher than that of the oil filter.
The filter element of diesel filter is mostly made of filter paper, but also made of felt and polymer materials. The main function of diesel filter is to filter mechanical impurities and water in diesel.

Gasoline filter
Gasoline filters are divided into carburetor type filters and electric injection type filters.
The engine using the carburetor filter is located on the inlet side of the oil pump, the working pressure is small, and the nylon shell is generally used.
Electric injection filter engine, the filter is located on the outlet side of the oil pump, the working pressure is higher, usually using a metal housing.
The filter element of the gasoline filter is mostly filter paper, and nylon cloth and polymer materials are also used.

Three, air filter

The concept of air filter
An air filter, located in the engine intake system, consists of one or more filter components that clean the air.
The main function of the filter is to filter out harmful impurities in the air entering the cylinder to reduce the early wear of the cylinder, piston, piston ring, valve and valve seat.

Classification of air filters
Air filters are divided into dry filter and wet filter 2 categories
Dry air filter, a filter that separates impurities from the air through a dry filter element.
The air filter used in light vehicles is generally a single stage, and the shape of the filter is oblate, oval and flat. The filter core material is filter paper and nonwoven fabric. The end cover of the filter element is metal or polyurethane, and the shell material is metal or plastic.
A heavy truck. Due to the harsh working environment, its air filter must be the majority. The material of the filter core is mostly nonwoven fabric, and filter paper is also used.
The wet air filter comprises an oil-immersed filter and an oil-bath filter.
Oil-immersed filter, through an oil-immersed filter element, the impurities in the air are separated, and the filter element material of the filter is metal wire fabric and foam material.
Oil bath type filter, the suction of dusty air into the oil pool, filter out most of the dust, and then further filtration. Oil bath type air filter, generally used in agricultural institutions, Marine power.

Air filter performance parameter index
1. Air flow
2. Work stress
3. Filtration accuracy
4. Original resistance pressure difference
5. Original filtration efficiency
6. Service life