The basic difference between a diesel and an internal-combustion engine is that during a diesel, the fuel is sprayed into the combustion chambers through fuel injector nozzles just when the air in each chamber has been placed under such great pressure that it’s hot enough to ignite the fuel spontaneously.
the following may be a step-by-step view of what happens once you begin a diesel-powered vehicle.
1.You turn the key within the ignition.
Then you wait until the engine builds up enough heat within the cylinders for satisfactory starting. (Most vehicles have a touch light that says “Wait,” but a sultry computer voice may do an equivalent job on some vehicles.) Turning the key begins a process during which fuel is injected into the cylinders under such high that it heats the air within the cylinders all by itself. The time it takes to warm things up has been dramatically reduced — probably no quite 1.5 seconds in moderate weather.
Diesel fuel is a smaller amount volatile than gasoline and is simpler to start out if the combustion chamber is preheated, so manufacturers originally installed little glow plugs that worked off the battery to pre-warm the air within the cylinders once you first started the engine. Better fuel management techniques and better injection pressures now create enough heat to touch off the fuel without glow plugs, but the plugs are still in there for emissions control: the additional heat they supply helps burn the fuel more efficiently. Some vehicles still have these chambers, others don’t, but the results are still equivalent.
2.A “Start” light goes on.
When you see it, you tread on the accelerator and switch the key to “Start.”
3.Fuel pumps deliver the fuel from the fuel tank to the engine.
On its way, the fuel passes through a few fuel filters that clean it before it can get to the fuel injector nozzles. Proper filter maintenance is particularly important in diesel because fuel contamination can clog the small holes within the injector nozzles.
4. The fuel injection system pump pressurizes fuel into a delivery tube.
This delivery tube has named a rail and keeps it there under a constant high of 23,500 pounds per sq in (psi) or maybe higher while it delivers the fuel to every cylinder at the right time. (Gasoline fuel injection system pressure maybe just 10 to 50 psi!) The fuel injectors feed the fuel as precipitation into the combustion chambers of the cylinders through nozzles controlled by the engine’s engine control unit (ECU), which determines the pressure, when the fuel spray occurs, how long it lasts, and other functions.
Other diesel oil systems use hydraulics, crystalline wafers, and other methods to regulate the fuel injection system, and more are being developed to supply diesel engines that are even more powerful and responsive.
5.The fuel, air, and “fire” meet within the cylinders.
While the preceding steps get the fuel where it must go, another process runs simultaneously to urge the air where it must be for the ultimate, fiery squeeze play.
On conventional types of diesel, the air comes in through an air filter that’s quite almost like those in gas-powered vehicles. However, modern turbochargers can ram greater volumes of air into the cylinders and should provide greater power and fuel economy under optimum conditions. A turbocharger can increase the facility on a diesel vehicle by 50 percent while lowering its fuel consumption by 20 to 25 percent!
6.Combustion spreads from the smaller amount of fuel that’s placed struggling within the precombustion chamber to the fuel and air within the combustion chamber itself.