The floating oil filter for collecting oil, in order to make the oil pump work well, must remove large particles of impurities in the lubricating oil before entering the oil pump; this task is performed by the oil collection filter. It is connected to the inlet of the oil pump. When the oil pump operates, oil is sucked in from the gap between the cover and the float. After filtering out coarse impurities through the filter screen, the oil pipeline, welded to the float, enters the oil pump. When the filter is filtered, the suction of the inlet pipe increases, the strength of the filter screen is overcome, and the bad mouth leaves the cover, while the oil enters the suction pipe directly from the annular mouth without the filter screen.
The raw filter is connected in series between the oil pump and the main oil channel, so it is also called a full-flow filter, which is used to remove large impurities in the oil. It mainly consists of the upper cover, housing, paper filter element, and bypass valve. When the engine operates, the lubricating oil is supplied under pressure to the cavity around the filter element, larger impurities in the oil are blocked by the paper filter element, and clean lubricating oil enters the inner cavity of the filter element, and then enters the main oil channel of the cylinder block through the oil outlet.
The fine filter: its function is to filter out fine impurities in the lubricating oil, usually in parallel with the main oil channel, there are two types: centrifugal and paper plate.
The structure of the centrifugal fine filter: the shaft cavity is fixed to the housing, the rotor housing and the end sleeve are integrated, located on the thrust bearing, and can rotate freely around the rotor shaft. The compression nut secures the rotor cover to the rotor housing, which is pressed by a spring to limit the axial movement of the rotor. Under the rotor are two nozzles that are opposite each other. When the engine starts, a small amount of oil is pumped from the oil pump and enters the filter through the oil port. If the oil pressure is less than 9 kPa, the inlet oil limiting valve closes, and the fine filter does not work. When the oil pressure exceeds 98 kPa, the pressure limiting valve gradually opens, and oil is discharged from the outlet through the central hole of the rotor shaft. Then through the oil well into the rotor, and from the two nozzles, so the reactive force should push the rotating arm. When the oil pressure rises to 294 kPa, the rotor speed can reach more than 5000 r/min. The proportion of impurities in the lubricating oil in the rotor cavity exceeds the proportion of impurities in the lubricating oil. Under the action of the rotating centrifugal force, it is thrown against the rotor wall and adheres to it. Clean lubricating oil in the center enters the two nozzles from the center and continuously exits outward, while the lubricating oil returns to the lower crankcase.