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Filter classification and principle

2015-12-31 View:

air filter

The air filter is located in the engine air intake system, which is composed of a filter assembly parts of one or several of the clean air. The main purpose of the air cleaner is going to remove harmful impurities in the air entering the cylinder, in order to reduce the early wear of cylinder, piston, piston rings, valve and valve seat. The air cleaner type has two kinds, namely dry and wet.

Dry air filter through a dry filter (e.g. paper filter) filter the impurities in the air isolated. Light-duty vehicles (including cars, mini car) air filter used for general single stage. Its shape is oval or elliptical and flat type. Filter material for filter paper or nonwoven cloth. The filter cover is metal or polyurethane, the shell is made of metal or plastic. At the rated air flow, the filtration efficiency of filter should be not less than 99.5%. Heavy vehicles because of poor working environment, the air filter must be the most. The first stage is cyclone pre filter (such as leaf ring, swirl tube, etc.) for filtering coarse particle impurities, filtering efficiency is more than 80%, second fine filtration is microporous paper filter (commonly known as the primary filter), the filtration efficiency is more than 99.5%. The main filter after a security filter, its function is to install and replace the filter, to prevent dust from entering the engine is damaged by accident or in the main filter. Safety of core materials for nonwovens, also use the filter paper.

Wet air filter includes oil immersed type and oil bath type two. Oil immersed type is through an oil filter and the separation of impurities in the air, the filter material with metal fabric and foam material. Oil bath type is the breathing is to remove most of the dust, then in the belt of oil mist from the air flows upward through a filter core is composed of a metal wire is wound into a for further filtering dust air import oil pool with oil droplets and stopped the dust returned to the pool. Oil bath type air filters are generally used for agricultural and marine power.

oil filter
The oil filter is located in the engine lubrication system. The upstream oil filter is the oil pump, the downstream parts is in need of engine lubrication. Oil filter function is to filter out harmful impurities from the oil sump oil, oil supply to clean the crankshaft, connecting rod, cam shaft, turbocharger, piston ring pair, lubrication, cooling, cleaning effect, thus prolonging the life span of these parts, machine oil filter can be divided by the structure change type, rotary type, centrifugal type; according to the arrangement in the system can be divided into full flow type, shunt type. Oil filter filter materials used in filter paper, blankets, metal mesh, non-woven etc..
Eighty years ago, the domestic engine used for changing type oil filter. The structure of the filter is to filter and other parts, such as a spring and a sealing ring into a metal shell, the shell core is fixedly connected with a metal rod through the filter seat. Can change the benefits of oil filter is the use of low cost, only need regular maintenance and replacement of the filter element can be; deficiency lies in the sealing point too much, maintenance and replacement of the filter element may be missing part, easy to cause the vulnerability, and the replacement of trouble.
Since the early eighty's. Since the first imported from Italy with a rotary filter production line, rotary type filter for domestic OEM approved by gradually. The characteristics of rotary type filter is internally provided with check valve, by-pass valve, sealing point only one overall replacement, greatly improving the sealing performance, and easy replacement of the filter material, use imported filter paper, so the high filtration efficiency, small flow resistance, long service life. Now the domestic car adopts the oil filter of this structure, most of the miniature car, large, medium and small passenger cars, light, medium truck and heavy truck and agricultural vehicles are using a rotary type oil filter.
Centrifugal oil filter has a rotor set in a shaft, and there are two opposite spray nozzle, when oil enters the rotor out from the nozzle, the rotor can rotate quickly, clean the rotor in oil, impurities in oil by centrifugal to the inner wall of the rotor, the nozzle the oil flow back to the oil pan.
The characteristics of centrifugal oil filter is stable, no need to replace the filter, as long as the regular demolition of the rotor, cleaning dirt deposition in the wall of the rotor can be used again. The life can be equal with the engine. It is the lack of complex structure, high price, heavy, higher technical requirements on the use of personnel.
Full flow oil filter, as mentioned before, can change the type of rotary type, centrifugal, to filter all the oil into the system. The shunt filter filter of 5%-10% oil pump fuel supply. Split type oil filter is a filter, it is usually combined with the full flow. The small power engine are based on full flow filter, large power diesel machine adopts full flow and shunt filtering device.
Fuel filter
Fuel filter, diesel filter, fuel filter and gas filter three. The fuel filter is filtering engine fuel gas system of harmful particles and water, to protect oil pump injector, cylinder liner, piston ring, such as, reducing wear to avoid blocking.
The structure of diesel filter is similar with the oil filter with replaceable type and rotary type two. But the bear working pressure and oil temperature resistant requirements higher than the oil filter is much lower, and its filtering efficiency is much higher than the oil filter. The filter of diesel filter with filter paper, have used blankets or polymer materials. Diesel filter except mechanical filter impurities in diesel oil, another important function is to filter water. The presence of water for fuel injection system of diesel engine has great harm, corrosion, wear, stuck or even worsen diesel combustion process. A diesel oil filter system in water is the main way of precipitation. Or is provided with a cavity in the lower part of the filter precipitation, or by precipitation is special. Whether it is the lower part of the filter cavity precipitation, precipitation or specialized are provided with a drain valve, when water accumulates to a certain amount of water to open the valve.
Carburetor EFI fuel filter and fuel filter, carburetor gasoline engine, gasoline filter is located in the pump inlet side, small pressure. In general, the nylon shell, EFI engine the fuel filter is located in the outlet side of the pump, high working pressure, usually by metal shell. The use of gasoline filter filter filter, also use nylon cloth, polymer materials.

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