Lesson Notes By Weeks and Term v4 - SHS 3
INTRODUCTION TO ENGINE TECHNOLOGY
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INTRODUCTION TO ENGINE TECHNOLOGY
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Subject: Applied Technology
Class: SHS 3
Term: 1st Term
Week: 1
Grade code: 3.1.1.LI.2
Strand code: 1
Sub-strand code: 1
Content standard code: 3.1.1.CS.1
Indicator code: 3.1.1.LI.2
Theme: AUTOMOTIVE TECHNOLOGY
Subtheme: INTRODUCTION TO ENGINE TECHNOLOGY
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This lesson introduces the vital system that powers compression ignition (CI), or diesel, engines. In Ghana, diesel engines are the heart of our economy. They power the tros-tros and buses that take us to school and work, the large trucks that transport cocoa and timber from our farms and forests, and the generators that provide electricity to our homes, schools, and hospitals during power outages ('dumsor'). Understanding how fuel gets from the tank to the engine is a fundamental skill for any aspiring technician or engineer. It helps in diagnosing common problems like engine sputtering, loss of power, or failure to start.
A. What is a Compression Ignition (CI) Engine?
First, let's be clear on what we are studying. A Compression Ignition (CI) engine, commonly known as a diesel engine, works differently from a petrol engine. Petrol Engine (Spark Ignition - SI): A mixture of air and petrol is drawn into the cylinder, compressed, and then ignited by a spark from a spark plug. Diesel Engine (Compression Ignition - CI): Only air is drawn into the cylinder and is compressed to a much higher pressure. This extreme compression makes the air incredibly hot (over 500°C). At the perfect moment, diesel fuel is sprayed (injected) into this hot air, and it ignites instantly due to the heat and pressure alone. There is no spark plug.
This difference is crucial. Because the diesel engine relies on high pressure and heat for ignition, its fuel system must be capable of delivering fuel at extremely high pressures. This makes it more complex than a typical petrol fuel system. B. The Main Components and their Functions
The fuel supply system is like the engine's circulatory system, with the fuel being the blood. It must deliver a precise amount of clean fuel, at the right time, and at a very high pressure. Let's follow the journey of the diesel fuel.