Main components of lubrication system by Asiautos Auto Parts(vehicles Aftermarket Parts Expert)

The main components of lubrication system are oil pump, oil filter, various valves, oil radiator and inspection equipment.

1. Oil pump

Function: Increase oil pressure and ensure continuous circulation of oil in lubrication system. At present, two types of oil pumps are widely used in engine lubrication system: external gear oil pump and internal gear rotor oil pump.

(1) Gear type mechanical pump (Figure 6-5)

The gear type oil pump consists of driving shaft, driving gear, driven shaft, driven gear, housing, etc. Two gears with the same number of teeth mesh with each other and are installed in the housing. The radial and end face clearance between the gear and the housing is very small. The driving shaft is keyed to the driving gear, and the driven gear is loosely sleeved on the driven shaft.

When working, the driving gear drives the driven gear to rotate in the opposite direction. When the two gears rotate, the oil filled between the gear teeth is carried from the oil inlet chamber to the oil outlet chamber along the wall of the oil pump casing. On one side of the oil inlet chamber, a vacuum is generated due to the disengagement of the gears and the continuous removal of the oil, so that the oil in the oil pan enters the oil inlet chamber through the filter under the action of atmospheric pressure. On the other side of the oil outlet chamber, the gears are engaged and the oil is continuously brought in, which creates an extrusion effect, and the oil is pumped out at a certain pressure.

The gear oil pump has a simple structure, convenient machining, reliable operation, long service life, and is widely used.

(2) Rotor oil pump (Figure 6-6)

The rotor oil pump consists of a housing, an inner rotor, an outer rotor, and a pump cover. The inner rotor is fixed to the rotor shaft with a key or pin and is driven directly or indirectly by the crankshaft gear. The eccentricity of the inner rotor and the outer rotor center is e, and the inner rotor drives the outer rotor to rotate in the same direction. The inner rotor has 4 convex teeth and the outer rotor has 5 concave teeth, so that the inner and outer rotors rotate in the same direction but not synchronously.

The tooth profile of the rotor is designed so that when the rotor rotates to any angle, the tooth profile of each tooth of the inner and outer rotors can always make point contact with each other. In this way, four working chambers are formed between the inner and outer rotors. As the rotor rotates, the volume of the four working chambers is constantly changing. In the cavity on one side of the oil inlet channel, the volume gradually increases due to the disengagement of the rotor, and a vacuum is generated. The oil is sucked in. The rotor continues to rotate and the oil is brought to the side of the oil outlet channel. At this time, the rotor just enters the meshing, which reduces the volume of this cavity, increases the oil pressure, and squeezes out from between the teeth and is pressed out through the oil outlet channel. In this way, as the rotor continues to rotate, the oil is constantly sucked in and pressed out.

The rotor oil pump has a compact structure, small size, light weight, large oil suction vacuum, large oil pumping volume, good oil supply uniformity, low cost, and is widely used in medium and small engines.

2. Oil filter

When the engine is working, metal grinding chips, dust in the atmosphere, and carbon particles produced by incomplete fuel combustion will penetrate into the engine oil. The engine oil itself will also produce colloidal sediments due to thermal oxidation, and the engine oil contains these impurities. If such dirty engine oil is directly sent to the surface of moving parts, the mechanical impurities in the engine oil will become abrasives, accelerate the wear of parts, and cause blockage of oil channels and agglutination of parts such as piston rings and valves. Therefore, an oil filter must be installed in the lubrication system to purify the circulating oil before it is sent to the surface of moving parts. Ensure good lubrication of the friction surface and extend its service life. Generally, several filters with different filtering capabilities are installed in the lubrication system, including a collection filter, a coarse filter, and a fine filter, which are connected in series and in parallel in the main oil channel respectively. The filter connected in series with the main oil channel is called a full-flow filter, which is generally a coarse filter; the filter connected in parallel with the main oil channel is called a split-flow filter, which is generally a fine filter, and the oil flow rate is about 10-30%.

(1) Filter (Figure 6-7)

The filter is a filter with a metal mesh, installed on the oil pump inlet pipe, and its function is to prevent larger mechanical impurities from entering the oil pump. The floating filter floats on the surface of the oil to absorb oil, and can absorb cleaner oil on the oil surface, but the foam on the oil surface is easily absorbed, which reduces the oil pressure and makes lubrication unreliable. It is not widely used at present. The fixed filter is submerged below the oil surface, and the oil absorbed is less clean, but it can prevent foam from being absorbed, and the lubrication is reliable. It has a simple structure and is gradually replacing the floating filter.

(2) Coarse filter

The coarse filter is used to filter out larger impurities in the oil, and has a small oil flow resistance. It is usually connected in series between the oil pump and the main oil channel, and is a full-flow filter. The coarse filter is a filtering filter. Its working principle is to use the impurities larger than the holes or gaps to leave them on the outside of the filter element when the oil passes through small holes or gaps. There are various structural forms depending on the filter element. Traditional coarse filters mostly use metal sheet gap type and winding type, but now paper type and sawdust type are mostly used.

1. Metal sheet gap type coarse filter (Figure 6-8)
2. 

The filter element of this coarse filter is composed of filter plates, spacers and scrapers made of thin steel sheets. They are mounted on the filter element shaft in the same way and compressed with upper and lower cover plates and nuts. Because there are spacers between the filter plates, a certain gap is formed, and the engine oil can flow into the filter element through this gap, and then flow to the main oil channel through the upper cover oil outlet channel. The direction of engine oil flow is shown by the arrow in the figure. A bypass valve is provided on the upper cover. When the filter element is blocked, the bypass valve is pushed open by the oil pressure, and the lubricating oil flows directly into the main oil channel without passing through the filter element, ensuring that the oil supply will not be interrupted.

1. Paper filter element type oil coarse filter (Figure 6-9)

The metal sheet type coarse filter is a permanent filter. Due to its disadvantages such as large mass, complex structure and high manufacturing cost, it has been basically eliminated. The filter element of the paper filter is made of microporous filter paper. In order to increase the filtering area, the microporous filter paper is generally folded into a fan shape and a corrugated shape (Figure 6-10). The microporous filter paper is treated with phenolic resin and has high strength, corrosion resistance and water resistance. It has the advantages of small mass, small volume, simple structure, good filtering effect, small filtering resistance, low cost and convenient maintenance. It has been widely used.

1. Sawdust filter element type engine oil coarse filter

The filter element of the sawdust filter element type coarse filter is a sawdust filter element bonded with phenolic resin. It has low resistance, good filtering effect and long service life.

(3) Fine filter

The engine oil fine filter is used to remove fine impurities. This filter has a large flow resistance to the engine oil, so it is mostly made into a split flow type. It is connected in parallel with the main oil channel. Only a small amount of engine oil passes through it and returns to the oil pan after filtering. There are two types of fine filters: filtering type and centrifugal type. The filtering type engine oil fine filter has a contradiction between filtering capacity and passing capacity. For this purpose, most engines use centrifugal fine filters.