1. The role of lubrication system

The lubrication system of a diesel engine, like other engine lubrication systems, is responsible for delivering a certain amount of clean and temperature appropriate lubricating oil to various friction surfaces for lubrication, in order to reduce the wear of moving parts; Clean and cool the friction surface; Improve the sealing performance of sealing moving parts such as piston rings and cylinder walls; And it has a rust proof effect on all moving parts.

2. Lubrication method

There are three lubrication methods for engines to deliver oil to the friction surface of moving parts: splash lubrication, pressure lubrication, and composite lubrication.

(1) Splash lubrication (also known as splash lubrication) is used for lubrication of friction parts with small loads, such as cylinder walls, camshafts of valve mechanisms, and tappets. The oil squeezed out from the clearance between the crankshaft main bearings and connecting rod bearings splashes onto the friction surface for lubrication. Alternatively, the lower part of the connecting rod big end can be used to excite the oil in the oil pan, causing the oil to splash and form oil droplets or mist, which fall onto the surface of the friction parts for lubrication, The lubricated oil still flows back to the oil pan. This lubrication method has a simple structure, but the lubrication is not reliable enough, consumes a large amount of engine oil, and is prone to oxidation and pollution.

(2) Pressure lubrication is used to lubricate friction surfaces that bear heavy loads and have high relative motion speeds, such as main bearings, connecting rod bearings, camshaft bearings, etc., by utilizing the pressure of the oil pump to send oil from the oil pan through oil passages and pipes to the friction surfaces of various moving parts for lubrication. This lubrication method is reliable, effective, and has good cleaning and cooling effects.

(3) Composite lubrication adopts both pressure lubrication and splash lubrication oil supply methods to lubricate the friction surfaces of the engine separately. Modern multi cylinder engines commonly use this lubrication method. Not only does it work reliably, but it can also simplify the structure of the entire lubrication system.

Due to the fact that the lubrication systems of various engines are basically the same, but some large and medium-sized diesel engines have different ways of accommodating lubricating oil, which can be divided into two categories: dry and wet cycle systems.

A. Dry cycle system: The oil is stored separately in the oil tank outside the engine, which is called a dry cycle system. The oil pan on the engine only collects the circulating oil from various lubrication parts, and then sends it to the oil tank for storage through the oil suction pump. The oil in the oil tank is sent to various friction surfaces through a pressure pump. This system is suitable for mobile large and medium-sized low-speed diesel engines.

B. Humidity circulation system: The oil is directly stored in the bottom of the oil tank, which is called a wet circulation system. Its characteristic is that it does not require an oil suction pump, and only two pressure pumps are needed to achieve oil circulation. This circulation system is used in small and medium-sized engines.

3. Composition of lubrication system

The composition of the lubrication system is determined based on the specific needs of the engine. The lubrication system of modern engines consists of the following basic components:

(1) The oil storage and transportation device includes an oil pump, oil pipeline, and oil pan, which circulate the oil within the engine.

(2) The oil filtration device includes a crude oil filter and a fine oil filter, which are used to filter various impurities contained in the oil.

(3) The oil cooling device has an oil cooler or oil radiator, which is used to cool the oil and prevent the oil temperature from being too high and affecting the normal operation of the engine.

(4) The safety protection devices include safety valves, pressure limiting valves, various alarm devices for high-power engines, and automatic shutdown devices for low oil pressure.

(5) The indicating device includes an oil temperature gauge, an oil pressure gauge, etc., to monitor the operation of the lubrication system.