Air filter is a device to remove particulate impurities in the air. When piston machinery (internal combustion engine, reciprocating compressor, etc.) works, if there are dust and other impurities in the inhaled air, it will aggravate the wear of parts, so it must be equipped with air filter. The air filter consists of a filter element and a housing. The main requirements of air filter are high filtration efficiency, low flow resistance, long time continuous use without maintenance. Air cleaner is mainly used in pneumatic machinery, internal combustion machinery and other fields. Its function is to provide clean air for these mechanical equipment, so as to prevent these mechanical equipment from inhaling air with impurity particles and increasing the probability of abrasion and damage. The main components of the air filter are the filter element and the casing, in which the filter element is the main filtering part, undertaking the work of gas filtration, and the casing is the external structure to provide the necessary protection for the filter element. The working requirement of the air filter is to be able to bear the high efficiency of air filtration, not to increase too much resistance for air flow, and to work continuously for a long time. It also has different degrees of application in the hydraulic system of hydraulic machinery, mainly used to adjust the internal and external pressure difference of the hydraulic system oil tank.
Oil filter is also known as oil grid. It is used to remove dust, metal particles, carbon deposits and soot particles in engine oil, and protect engine. The oil filter can be divided into full flow type and split flow type. The full flow filter is connected in series between the oil pump and the main oil passage, so it can filter all the lubricating oil into the main oil passage. The shunt cleaner is connected in parallel with the main oil passage, and only part of the lubricating oil sent out by the oil pump of the filter. In the process of engine operation, metal debris, dust, oxidized carbon and colloidal deposits at high temperature, water, etc. are constantly mixed with lubricating oil. The function of oil filter is to filter out these mechanical impurities and colloids, keep the lubricating oil clean and extend its service life. The oil filter should have the characteristics of strong filtration capacity, small flow resistance and long service life. In general, several filters with different filtration capacity are installed in the lubrication system, namely, the collector, the coarse filter and the fine filter, which are respectively connected in parallel or series in the main oil passage. (the one connected in series with the main oil passage is called full flow filter. When the engine is working, all the lubricating oil is filtered by the filter; the one connected in parallel is called split flow filter). The primary filter is connected in series in the main oil passage, which is full flow type; the secondary filter is connected in parallel in the main oil passage, which is split flow type. Modern car engines are generally equipped with only a filter and a full flow oil filter. The coarse filter is used to filter the impurities with particle size of more than 0.05mm, while the fine filter is used to filter the small impurities with particle size of more than 0.001mm.
Gasoline filter is referred to as steam filter. The gasoline filter can be divided into carburetor type and EFI type. For the gasoline engine with carburetor, the gasoline filter is located at the inlet side of the fuel transfer pump, with low working pressure, and generally adopts nylon shell. The gasoline filter of EFI engine is located at the outlet side of the fuel transfer pump, with high working pressure, and usually adopts metal shell. Filter paper is often used in the filter element of gasoline filter, and nylon cloth and polymer material are also used. The main function of gasoline filter is to remove impurities in gasoline. If the gasoline filter is dirty or blocked. Linear filter paper gasoline filter: the gasoline filter is inside this kind of gasoline filter. The folded filter paper is connected with both ends of the plastic or metal filter. After the dirty oil enters, it is filtered by layers of filter paper from the outer wall of the filter to the center, and the clean fuel flows out.
