Introduction-to-the-Automotive-Four-Stroke-Engine.pptx

Introduction to Automotive the Four-Stroke Engine

1. Introduction to the Automotive Four-Stroke Engine The four-stroke engine is the most common type of internal combustion engine used in automobiles. It operates through a sequence of four distinct steps: intake, compression, power, and exhaust, each playing a crucial role in the engine's efficient operation. by LEE SALVALEON

2. The Four Strokes: Intake, Compression, Power, and Exhaust 1 Intake The piston moves downward, drawing in the air-fuel mixture through the open intake valve. 2 Compression The piston moves upward, compressing the air-fuel mixture to prepare for ignition. 3 Power The compressed air-fuel mixture is ignited, driving the piston downward and generating power. 4 Exhaust The piston moves upward, expelling the spent gases through the open exhaust valve.

3. Intake Stroke: Drawing in the Air-Fuel Mixture 1 Cylinder Intake The piston moves downward, creating a vacuum that draws in the air-fuel mixture through the open intake valve. 2 Valve Timing The intake valve opens at the beginning of the intake stroke and closes at the end, ensuring efficient intake of the mixture. 3 Fuel Injection In modern engines, fuel is injected directly into the cylinder or the intake manifold, providing a precise air-fuel ratio.

4. Compression Stroke : Compressing the Air-Fuel Mixture Piston Movement The piston moves upward, reducing the volume of the cylinder and compressing the air-fuel mixture. Valve Timing Both the intake and exhaust valves are closed during the compression stroke, trapping the mixture for efficient compression. Compression Ratio The compression ratio, typically between 8:1 and 11:1, determines the engine's power and efficiency.

5. Power Stroke: Ignition and Expansion Ignition The compressed air-fuel mixture is ignited by the spark plug, causing a rapid expansion that drives the piston downward. Expansion The expanding gases push the piston down, converting the chemical energy of the fuel into mechanical energy to power the vehicle. Valve Timing The exhaust valve remains closed during the power stroke, allowing the maximum force to be transmitted to the crankshaft.

6. Exhaust Stroke: Expelling the Spent Gases Exhaust Valve Opening The exhaust valve opens, allowing the spent gases to be expelled from the cylinder. Piston Rises The piston moves upward, pushing the exhaust gases out of the cylinder and through the exhaust system. Cycle Completion The four-stroke cycle is completed, ready to repeat the sequence for the next power stroke.

7. Key Components of the Four-Stroke Engine Piston Converts the energy of the expanding gases into rotational motion. Crankshaft Transforms the reciprocating motion of the pistons into rotational motion. Valves Control the intake and exhaust of the air-fuel mixture and spent gases. Spark Plug Ignites the compressed air-fuel mixture, initiating the power stroke.

8. Benefits and Advantages of the Four-Stroke Engine Efficiency The four-stroke cycle allows for a more efficient use of fuel, resulting in improved fuel economy. Power Delivery The power stroke provides a continuous and smooth power delivery, making the engine well-suited for automotive applications. Durability The four-stroke design is relatively simple and robust, contributing to the engine's overall reliability and longevity. Emissions Advancements in engine technology have helped reduce emissions from four-stroke engines, making them more environmentally friendly.