Otto Cycle in Internal Combustion Engines

Summary:

The text discusses the Otto Cycle, an air-standard cycle used in Gas/Petrol Engines (Spark-Ignition Engines). It was developed by Nikolaus Otto in 1876 and is known for its four-stroke process. The key components of a Spark-Ignition Engine are the spark plug, carburettor, and fuel pump. The cycle involves four processes: Suction Stroke, Compression Stroke, Expansion Stroke, and Exhaust Stroke. There are three types of Ignition Systems: Coil-ignition, Magneto-ignition, and Electronic-ignition systems. Each system serves the purpose of generating a spark to ignite the air-fuel mixture in the combustion chamber. The Electronic Ignition System has three types: Transistorized Ignition System, Distributor-less Ignition System, and Capacitive-discharge Ignition System.

Overall, the text provides an overview of the Otto Cycle, its components, and the types of Ignition Systems used in Spark-Ignition Engines.

Excerpt:

Otto Cycle in Internal Combustion Engines

A. WHAT IS AN OTTO CYCLE?

An Otto Cycle is an air-standard cycle that uses constant-volume heat addition or isometric heat addition. Nikolaus Otto, a German scientist, developed the first practical four-stroke engine (the Otto Silent Engine) with in-cylinder compression 1876. It produced 2 HP at 160 rpm using a compression ratio 2.5, and a brake efficiency of 14%. He was the first person to be recognized as the founder of the internal combustion engine industry. The Otto Cycle is the ideal air-standard cycle for Gas/Petrol Engines, commonly known as the Spark-Ignition Engine (sometimes called constant volume cycle or volume cycle) because of the use of a spark plug to produce combustion, which means it takes place at the top dead centre.

B. PARTS PRESENT IN A SPARK-IGNITION ENGINE

1. Spark Plug – For high potential conduction from the ignition system into the combustion chamber, it produces a spark by applying a high voltage (6 to 10 kV) in 0.001 seconds to ignite the combustion chamber 30 degrees before TDC. It has an average gap of 1.2 mm. The ignition quality of petrol is expressed by the octane number, commonly ranging from (80 to 100). If the mixture ignites due to compression before the spark, it is called pre-ignition. Hot Carbon or lead deposits can also be the cause for pre-ignition.