Engine work, if the oil strainer seriously blocked by impurities, or due to low temperature and oil viscosity becomes large, the main oil will be lack of oil, the engine will lose lubrication, which is very dangerous, especially the main bearing and the Rod bearings, if there is no oil will burn out, the bearing alloy due to friction and heat loss, and even welded together with the journal, and ultimately force the engine to stop working. In order to avoid this problem, a bypass valve (safety valve) is installed in the lubrication system in parallel with the strainer. When the strainer is blocked, the pressure difference between the inlet and the outlet does not reach a certain value, the bypass valve is pushed open and the oil flows into the main oil passage without passing through the strainer directly through the bypass valve. At this point lubrication is the main, while the filter is secondary. The oil entering the main gallery, though not filtered a little dirty, but the engine will not lose the necessary normal lubrication due to the lack of lubricating oil, to prevent dry friction. In order to prevent the lubrication system of high oil pressure and increase engine power consumption, resulting in sealing joints in the oil leakage, etc., in the main oil or oil pump with a pressure limiting valve. Its role is to limit the oil pressure lubrication system, so that it does not exceed the specified value. Its working principle is: when the oil pressure in the lubricating oil system of the engine exceeds the specified value, the pressure limiting valve is pushed open, excess lubricating oil will flow back to the oil sump or the oil inlet of the oil pump to reduce the oil pressure. The higher the hydraulic pressure, the larger the pressure-limiting valve opening, the more lubricant will flow back to the oil pan and the more the hydraulic pressure will drop. When the lubrication system oil pressure down to normal pressure, pressure limiting valve in the spring will reset. Oil bypass valve and the oil pressure limiting valve in the course of the interaction, in close cooperation, to achieve the best results, and effectively improve the work efficiency of the engine!
