A car engine needs lubrication as it consists of two or more moving parts. These parts produce friction and generate heat, which causes excessive wear and tear on the pairs. The engine lubrication system 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 into physical contact with each other.
In this reading, we’ll explore what an engine lubrication system is, its functions, diagram, parts, types, and how it works.
Let’s get started!
What Is an Engine Lubrication System?
An engine lubrication system in an internal combustion engine is a system that aids in lubricating and cooling the moving parts in an engine. It functions by using a flow of lubricants to separate and protect metal parts from rust and wear. Lubricants are available in liquid, solid, or gas, but liquid is the most common form of lubrication used in engines.
Automobiles are designed with indicator lights that are “on” when the engine oil pressure is low. Although some engine use the indicator to show the quality of the oil in the engine,. Electric analogue 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.
Functions Of Engine Lubricating System
Below are the functions of lubricating oil in an engine:
- The primary purpose of engine lubrication is to minimise wear by securely closing the clearance between moving parts such as shafts, bearings, etc. Lubrication also prevents the moving parts from coming into direct contact with each other.
- Oil serves as a cleaning agent in an engine as it moves dirt particles to the oil pan. The oil filters filter out smaller particles, while the oil pan retains larger ones.
- Another purpose of engine lubrication is that it serves as a cooling system. Lubricating oil cools the moving parts of the engine and transfers 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 bearings is filled with oil. The oil acts as a cushioning agent when the bearing suddenly experiences heavy loads. Oils reduce the wear on bearings.
Related: Difference Between Petrol and Diesel Engines
Diagram Of Engine Lubrication System
Parts of Engine Lubricating System
Here are the key parts of an engine lubricating system:
Oil Pan/Sump
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 beneath the engine, making the oil easily removed through the bottom.
Oil Pump
The oil pump is a component that helps 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 Filter
The oil filter helps to keep small particles separate 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.
Oil Galleries
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 transfer oil to parts that require it.
Oil Cooler
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 stabilise the temperature of the engine oil, keep its viscosity under control, prevent the engine from overheating, minimise wear and tear, and retain the lubricant quality
Key Engine Parts that Rely on Lubrication
Certain engine lubrication systems circulate oil throughout the engine during the recycling process. Here are the components that receive oil during this 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)
- Camshafts and bearings
- Valves
- 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
Engine lubrication systems are crucial for reducing friction, dissipating heat, and ensuring the smooth operation of engine components. Here are the main types of engine lubrication systems:
Mist Lubrication System
This is the type used in two-stroke engines where oil and fuel are mixed. The mixture is generated through the carburetor. The fuel gets vaporised 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
The 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.
Related: What Is A Four-stroke Engine? Its Diagram, Stroke Cycle, and Working
How Engine Lubricating System Works
The working of two-stroke and four-stroke engines are quite different, as is their lubrication system. These internal combustion engines produce mechanical power from chemical energy contained in hydrocarbon fuels. Lubrication is required to reduce wear and tear on these engine components and improve engine performance.
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 a pressurised lubrication pump system, which is the most preferred 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
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. Furthermore, a two-stroke engine designed with oil injection injects oil directly into the engine, where it mixes with the fuel. In a premix two-stroke engine, oil and fuel are mixed before pouring them into the fuel tank.