Oil pan classification

Wet

Most of the cars on the market are wet oil pans. The reason why they are named wet oil pans is that the crankshaft crank and connecting rod big end of the engine will be immersed in the lubricating oil of the oil pan once every revolution of the crankshaft to play a lubricating role. At the same time, due to the high-speed operation of the crankshaft, each time the crank is immersed in the oil pool at a high speed, it will cause a certain amount of oil spray and oil mist to lubricate the crankshaft and bearing bush, which is called splash lubrication. In this way, there are certain requirements for the liquid level of lubricating oil in the oil pan. If it is too low, the crankshaft crank and connecting rod big end cannot be immersed in the lubricating oil, resulting in lack of lubrication and smooth crankshaft, connecting rod and bearing bush; If the lubricating oil level is too high, it will cause the whole bearing to be immersed, which will increase the rotation resistance of the crankshaft, and eventually cause the engine performance to decline. At the same time, the lubricating oil is easy to enter the cylinder combustion chamber, resulting in engine oil burning, carbon deposition on the spark plug and other problems.

This lubrication method is simple in structure and does not need to set an oil tank. However, the inclination of the vehicle should not be too large, otherwise, the oil cut-off and oil leakage may cause the burning of the bearing pad and cylinder.

Dry

Dry sump is used in many racing engines. It does not store oil in the oil pan, more accurately, there is no oil pan. The friction surfaces of these movements in the crankcase are lubricated by pressing out the oil through the measuring holes. Since the dry-type oil pan engine cancels the oil storage function of the oil pan, the height of the crude oil pan is greatly reduced, and the height of the engine is also reduced. The advantage of the lower center of gravity is that it is conducive to control. The main advantage is to avoid various adverse phenomena of wet oil pan caused by intense driving.

However, the pressure of lubricating oil is all from the oil pump. The power of the oil pump is connected by gears through the rotation of the crankshaft. Although the oil pump is also required to provide pressure lubrication for the camshaft in the wet sump engine. However, the pressure is very small, and the oil pump requires very little power. However, in an engine with a dry oil pan, the strength of this pressure lubrication needs to be much greater. Moreover, the size of the oil pump is much larger than that of the oil pump of the wet sump engine. Therefore, the oil pump needs more power at this time. Like a supercharged engine, the oil pump needs to consume part of the power of the engine. Especially at high speed, when the engine speed increases, the motion intensity of the friction parts increases, and more lubricating oil is required. Therefore, the oil pump is required to provide greater pressure, and the consumption of crankshaft power is also increased.

Obviously, this design is not suitable for ordinary civil vehicle engines, because it needs to lose part of the power of the engine, which will not only affect the power output, but also not conducive to improving the economy. Therefore, the dry oil pan can only be equipped on large displacement or high-power engines, such as those sports cars for intense driving. For example, Lamborghini adopts the design of dry oil pan. For it, it is more important to improve the lubrication effect at the limit and obtain a lower center of gravity. The loss of power can be compensated by increasing the displacement and other aspects. As for economy, it is completely unnecessary to consider this type of vehicle.