4. Structure of centrifugal fine filter: the hollow shaft is fixed on the shell, and the rotor body and end sleeve are connected together. It is located on the thrust bearing and can rotate freely around the rotor shaft. The compression nut fastens the rotor cover to the rotor body, and the upper part is pressed by spring to restrict the axial movement of the rotor. Under the rotor, there are two nozzles which are opposite to each other. When the engine is running, a small part of the engine oil is pumped from the oil pump into the filter through the oil port. When the oil pressure is lower than 9s kpa, the inlet pressure limit valve is closed, and the fine filter does not work. When the oil pressure exceeds 98 kpa, the pressure limit valve gradually opens, the oil through the central hole of the rotor shaft, from the oil hole. Then through the oil hole into the rotor body, and ejected from the two nozzles, so the jet reaction force is to push the hand rotation. When the oil pressure rises to 294 kpa, the rotor speed can reach more than 5000r/min. The proportion of impurities in the lubricating oil in the inner cavity of the rotor is larger than that of the lubricating oil. Under the action of rotating centrifugal force, the impurities are thrown to the rotor wall and covered on the wall. Clean lubricating oil at the center, from the center into the two nozzles, constantly spray outwards, ejected lubricating oil flow back down