An automotive engine needs lubrication as they comprise two or more robing, moving parts. These parts produce friction and generate heat which causes excessive wear and tear of the pairs. Lubrication plays a vital role in automobiles as it aids the working efficiency and longevity of an engine. When two moving parts experience a film of lubrication, they are separate from each other. That is, they do not come in physical contact with each other.
Automobiles are designed with indicator lights that are “on” when the engine oil pressure is low. Although some engine uses the indicator to show the quality of the oil in the engine. Electric analog and electronic digital gauges are used to indicate the oil pressure. A dipstick is also available to measure the oil level in the oil pan.
Today we’ll be looking at the definition, parts, functions, types, and diagram of engine lubrication systems in automobiles.
What is Engine Lubrication?
Engine lubrication is the process in which robing metal parts are separated by the flow of lubricating substances between them. lubricants are available in liquid, solid, or gas, but liquid is the most form of lubrication used in engines.
Functions of Engine Lubricating System
Below are the functions of lubricating oil in an engine:
- The primary purpose of engine lubrication is to minimize wear by securely closing the clearance between moving parts such as shafts, bearings, etc. Lubrication also avoids the moving parts not to come in direct contact with each other.
- Oil serves as a cleaning agent in an engine as it moves the dirt particle to the oil pan. Smaller particles are filtered out by the oil filters while larger ones are retained in the oil pan.
- Another purpose of engine lubrication is that it serves as a cooling system. Lubricating oil cools the moving parts of the engine and transferred the hot oil into the cooler oil in the oil pan.
- The oil creates a seal between the cylinder walls and the piston rings. It also reduces the exhaust gas blowby.
- Clearance between the rotating journals and bearing is filled with oil. The oil acts as a cushioning agent when the bearing suddenly experiences heavy loads. Oils reduce the wear on bearings.
Major Parts of Engine Lubricating System
The following are lubrication system components:
An oil sump is a reservoir in the shape of a bowl that stores the engine oil. With the sump, the oil circulates within the engine. The part is located below the crankcase which is the beneath the engine, making the oil to be easily removed through the bottom. Bad roads often cause damage to the oil pan. This is why the sump is made with hard material and featured a stone guard at it underneath. This sump guard withstands any hits from uneven ground or bad roads.
The oil pump is a component that helps to push the lubricating oil to all the moving parts in the engine. It’s located at the bottom of the crankcase, close to the oil sump. It supplies oil to the oil filter before sending it further. Oil pumps can eventually stop working, which may lead to damage to the engine. It can be caused by small particles inside the lubricating oil, which choke the oil pump and galleries. To avoid this problem, changing the engine oil and filter is very necessary within some period of time.
The oil filter helps to keep small particles, separating them from the oil so that clean oil can flow to the engine parts. The oil pump allows the oil to flow through the oil filter to the galleries before reaching the engine parts.
The function of oil galleries in the engine lubrication system is to circulate oil quickly to reach all moving parts in automobiles. So, the performance of an oil gallery determines how fast your engine parts received oil. The oil galleries are a series of interconnected passages that transfers oil to parts that requires it. These passages are big and small holes drilled inside the cylinder block. The bigger holes are connected to the smaller ones until it reaches the cylinder head and overhead camshafts.
An oil cooler is a device that works as a radiator as it cools down the hot oil. Coolers transfer the heat from the engine oil to the engine coolant using its fins. Oil coolers stabilize the temperature of the engine oil, keep its viscosity under control, prevent the engine from overheating, minimize wear and tear as well as retain the lubricant quality
Some engine lubricating system circulates oil within the engine with the recycling process. The following are the parts that oil is supplied during the process:
- Crankshaft main bearings
- Big end bearings
- Piston pins and small end bushes
- Piston rings
- Timing Gears
- Air-compressor piston and bearings (in commercial vehicles for air-brake)
- Camshaft and bearings
- Cylinder walls
- Oil pump parts
- Water pump bearings
- Turbocharger bearings (if available)
- Vacuum pump bearings (if available)
- In-Line Fuel Injection Pump bearings
- Tappets and push-rods
Types of Engine Lubrication Systems
Below are the types of engine lubrication systems:
Mist Lubrication System: is the type used in two-stroke engines where oil and fuel are mixed. The mixture is generated through the carburetor.
The fuel gets vaporized while the oil in the form of a mist enters the cylinder through a crank base. In the crank base, the oil lubricates the connecting rod along with the piston ring, piston, and cylinder.
Wet Sump Lubricating System: is generally located next to or near the crankshaft. it’s the lower part of the engine and it has a single oil pump. This pump moves the oil through the oil galleries. The construction is easier and it’s unexpansive.
Dry Sump Lubricating System: a dry-sump system has an oil reservoir that is not located at the bottom of the engine. It uses two oil pumps to keep the oil circulating within the engine. The system is more complex and expensive to design. However, there’s more flexibility to the design of the pan as it’s located in an unusual place. It is often found in performance engines.
Lubricating System in Two-stroke and Four-stroke engines
The working of two-stroke and four-stroke engines are quite different the same as their lubrication system. These internal combustion engines produce mechanical power from chemical energy contained in hydrocarbon fuels. The working of these engine components requires lubrication to minimize wear and tear so as for engine effectiveness.
The major difference between the engines is that two-stroke engines have a power stroke or expansion in each cylinder during each revolution of the crankshaft. The exhaust and the intake process occur simultaneously as the piston moves through its lowest. While
A four-stroke engine requires two complete turns of the crankshaft to make a power stroke. burnt gases are firstly displaced by the piston during an upward stroke. Fresh charge enters the cylinder during the next downward stroke.
Lubrication in Four-stroke Engine
In the lubrication of four-stroke engines, oil is stored in an oil sump or pan. The oil circulates within the engine through splash lubrication or pressurized lubrication pump system which is the most preferable choice by manufacturers. Although the two can be featured together in an engine.
The splash lubrication happens when the crankshaft is partly immersed in an oil sump. The momentum of the rotating crankshaft splashes oil to other components in the engine such as the cam lobes, cylinder walls, wrist pin, etc.
Pressurized lubrication is achieved using an oil pump to push the film of lubricant between moving parts such as the main bearings, rod bearings, and cam bearings. It also pumps oil to the engine’s valve guides and rocker arms.
Two-stroke Engine Lubrication
Generally, two-stroke engines tend to wear more quickly as there is no lubrication source in them. but there is a high-quality oil that significantly reduces engine wear.
Two-stroke engines receive oil beneath the crankshaft using a total-loss lubrication system. This lubricating system combines both oil and fuel to provide both energies for engine lubrication.
The two agents are combined in the cylinder’s intake tract and lubricate components such as crankshaft, connecting rod, and cylinder walls.
Two-stroke designed with oil injection injects oil directly into the engine where it mixes with the fuel. In a premix two-stroke engine, oil-fuel is mixed before pouring it into the fuel tank.
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