The coarse filter is connected in series between the oil pump and the main oil passage, so it is also called a full-flow filter, which is used to remove larger impurities in the oil. It is mainly composed of upper cover, shell, paper filter element and bypass valve. When the engine is working, the lubricating oil with pressure is sent into the cavity around the filter element and into the cavity around the filter element, the larger impurities in the oil are blocked by the paper filter element, and the clean lubricating oil enters the inner cavity of the filter element, and then passes through the oil outlet. into the main oil passage of the cylinder block.
Fine filter: its function is to filter out smaller impurities in the lubricating oil, usually in parallel with the main oil channel, there are centrifugal and cardboard types.