What are the two major categories of internal combustion engines?
3 Answers
Internal combustion engines can be classified by cooling method into air-cooled and water-cooled types; by the number of cylinders, they can be divided into single-cylinder and multi-cylinder engines, among others. Broadly speaking, they are categorized into free-piston internal combustion engines, reciprocating piston internal combustion engines, and rotary piston internal combustion engines, which also include jet engines and rotary turbine gas engines. Based on the type of fuel used, internal combustion engines can be classified into gasoline engines, diesel engines, and gas-fueled engines. Engines that use gasoline as fuel are called gasoline engines; those that use diesel are called diesel engines, while gas fuels mainly include natural gas, liquefied petroleum gas, and others.
The most common classification of internal combustion engines falls into two major categories: gasoline engines and diesel engines. Having worked on so many vehicles, I can say gasoline engines rely on spark plugs for ignition, typically with a compression ratio of 9 to 12. They operate quietly and accelerate quickly, making them the standard choice for passenger cars. Diesel engines, on the other hand, operate on compression ignition with a higher compression ratio ranging from 16 to 22. They deliver more torque and are more fuel-efficient, albeit noisier, which is why they're commonly found in trucks and tractors. Recently, I've noticed advancements in diesel technology, with some passenger cars now adopting turbocharged diesel versions that significantly reduce fuel consumption.
Two types: spark ignition and compression ignition. Gasoline vehicles are typical examples of spark ignition engines, which require spark plugs to generate electrical sparks to ignite the gasoline-air mixture. Those who have driven diesel pickups know the power of the other type, the compression ignition engine, which relies solely on compression to generate high temperatures for diesel self-ignition, delivering exceptional explosive force, especially noticeable when hauling loads or climbing slopes. The fuel injection methods of these two engines are completely different, one being intake manifold injection and the other direct cylinder injection.
