The principle of operation of a diesel engine - photo and video of the process
Machine operation

The principle of operation of a diesel engine - photo and video of the process


Diesel engines have managed to go through a long and successful path of development from inefficient and polluting units of the early twentieth century to the super economical and completely silent ones that are now installed in a good half of all cars produced today. But, despite such successful modifications, the general principle of their operation, which distinguishes diesel engines from gasoline engines, has remained the same. Let's try to consider this topic in more detail.

The principle of operation of a diesel engine - photo and video of the process

What are the main differences between diesel engines and gasoline engines?

It is already clear from the name itself that diesel engines do not run on gasoline, but on diesel fuel, which is also called diesel fuel, diesel fuel or just diesel. We will not delve into all the details of the chemical processes of oil refining, we will only say that both gasoline and diesel are produced from oil. During distillation, oil is divided into different fractions:

  • gaseous - propane, butane, methane;
  • sledges (short chain carbohydrates) - used for the production of solvents;
  • gasoline is an explosive and rapidly evaporating transparent liquid;
  • kerosene and diesel are liquids with a yellowish tinge and a more viscous structure than gasoline.

That is, diesel fuel is produced from heavier fractions of oil, its most important indicator is flammability, determined by the cetane number. Diesel fuel is also characterized by a high sulfur content, which, however, they are trying to reduce by all means so that the fuel meets environmental standards.

Like gasoline, diesel is divided into different types depending on temperature conditions:

  • summer;
  • winter;
  • arctic.

It is also worth noting that diesel fuel is produced not only from oil, but also from various vegetable oils - palm, soybean, rapeseed, etc., mixed with industrial alcohol - methanol.

However, the fuel being poured is not the main difference. If we look at the gasoline and diesel engines “in the context”, then we will not notice any visual difference - the same pistons, connecting rods, crankshaft, flywheel, and so on. But there is a difference and it is very significant.

Diesel engine working principle

Unlike gasoline, in a diesel engine, the air-fuel mixture is ignited according to a completely different principle. If in gasoline - both in carburetor and injection - engines, the mixture is first prepared and then ignited with a spark from a spark plug, then in a diesel engine air is injected into the combustion chamber of the piston, then the air is compressed, heating up to temperatures of 700 degrees, and at this moment, fuel enters the chamber, which immediately explodes and pushes the piston down.

The principle of operation of a diesel engine - photo and video of the process

Diesel engines are four-stroke. Let's look at each beat:

  1. The first stroke - the piston moves down, the intake valve opens, thereby air enters the combustion chamber;
  2. The second cycle - the piston begins to rise, the air begins to compress and heat up under pressure, it is at this moment that diesel fuel is injected through the nozzle, it ignites;
  3. The third stroke is a working one, an explosion occurs, the piston begins to move down;
  4. The fourth stroke - the exhaust valve opens and all the exhaust gases exit into the exhaust manifold or into the turbine nozzles.

Of course, all this happens very quickly - several thousand revolutions per minute, it requires very coordinated work and adjustment of all components - pistons, cylinders, camshaft, crankshaft connecting rods, and most importantly sensors - which must transmit hundreds of pulses per second to the CPU for instant processing and calculation of the required volumes of air and diesel fuel.

Diesel engines give out a greater efficiency, which is why they are used on trucks, combines, tractors, military equipment and so on. DT is cheaper, but it should be noted that the engine itself is more expensive to operate, because the compression level here is almost twice as high as in gasoline, respectively, pistons of a special design are needed, and all components, parts and materials used are reinforced, that is, they cost expensive.

Also, very strict requirements are placed on fuel supply and exhaust gas systems. Not a single diesel engine can work without a high-quality and reliable high-pressure fuel pump - a high-pressure fuel pump. It ensures the correct supply of fuel to each nozzle. In addition, diesel engines use turbines - with their help, exhaust gases are reused, thereby increasing engine power.

The diesel also has a number of problems:

  • increased noise;
  • more waste - the fuel is more oily, so you need to regularly change filters, monitor exhaust;
  • problems with starting, especially cold, a more powerful starter is used, the fuel thickens quickly when the temperature drops;
  • repairs are expensive, especially for fuel equipment.

In a word - to each his own, diesel engines are characterized by greater power, are associated with powerful SUVs and trucks. For a simple city dweller who goes to work - from work and leaves the city on weekends, a low-powered gasoline engine is enough.

Video showing the whole principle of operation of a diesel internal combustion engine




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