The story of diesel engines actually started with the invention of gasoline engines. In 1876, Nikolaus Otto invented the gasoline engine. his invention is referred to as the "Otto Cycle" which describes the current 4-stroke combustion principle.
When the gasoline engine was first invented, it was found that they were not efficient enough compared to steam engines. This was because only 10% of the fuel could be used to move the vehicle. The remaining heat disappeared from use.
On February 23, 1893, Rudolf patented the engine, now known as the diesel engine, by developing and developing the working principle of the diesel petrol engine. Diesel engines operate more noisy than gasoline engines and emit more black smoke. In general, users do not prefer diesel engines for these reasons. However, diesel engines are preferred for vehicles that will travel long and carry heavy loads (trucks, trucks, etc.). In line with the reasons why people prefer it or not, studies have started to make diesel engines more environmentally friendly and less noisy.
Comparison of Diesel Engines and Gasoline Engines
Theoretically, gasoline and diesel engines are very similar. Both engine types are designed as internal combustion engines that convert the chemical energy they obtain through their fuel into mechanical energy. The produced mechanical energy pistons move up and down in the cylinders. By means of these linear movements and the crank, the power is transmitted to the wheels by making the vehicle move by converting to circular motion.
Both diesel and gasoline engines convert fuel into energy after a series of explosions. The main difference between diesel and gasoline engines; These are the formation of these explosions in the engine.
In gasoline engines, gasoline is taken into the cylinder by mixing with air, compressed with piston and ignited with spark plug and explosion event is formed. In diesel engines, the air taken in is compressed and then fuel is sprayed. Because in diesel engines, the compressed air is heated and thus the fuel spontaneously ignites.
The four-cycle combustion cycle takes place as follows;
1) Suction Stroke: As the piston moves downwards, the valves open and take in air.
2) Compression Stroke: The piston moves up and compresses the air.
3) Combustion Stroke: When the piston reaches the top point, the upper dead point, the fuel is sprayed and ignited at the appropriate moment, the piston moves downwards.
4) Exhaust Stroke: The combustion gases formed by the piston moving up again are discharged with the opening of the valves.
Diesel engines do not have spark ignition. The compressed air reaches a very high temperature and automatically ignites the fuel.
Fuel Injection System in Diesel Engines
The biggest difference between diesel and gasoline engines is; injection process. Many automobile engines have a carburetor. The carburetor mixes air and fuel well before it enters the cylinder. Thus, all the fuel is taken into the cylinder when it is time to suck and then compressed. The air and fuel mixture is compressed according to the compression ratio of the engine. If the compression is too high, a sudden explosion will occur due to overheating, causing a knock. This knock causes damage to the engine.
In diesel engines, direct injection system is used. That is, the fuel is sprayed directly into the cylinder. In diesel engines, injectors are the most complex components of diesel engines. The injectors must be pressure and high temperature resistant and deliver the fuel into the cylinder in atomized form.
The fuel must be swirled into the cylinder and evenly distributed. For this reason, some diesel engine engineers are working to create a suitable vortex from the combustion chamber by developing special electromagnetic injector-like equipment in the form of a pre-combustion chamber. In other words; engine ignition and compression systems are trying to improve.
Some diesel engines have glow plugs. when the engine is cold, the compression process may not be able to achieve the temperature level sufficient to ignite the air. Glow plugs are powered by electricity. In addition, it warms the air in the combustion chamber and brings it to the appropriate temperature level for the engine to start. After the engine has started, the glow plugs close as completed.
A modern engine is controlled by the ECU (Electronic Control Unit). All information measured by the sensors is transmitted to the ECU. Engine temperature, oil pressure,