How a diesel engine works
In a diesel engine, clean air is pumped into the cylinders and is strongly compressed there. As a result, the temperature in the cylinders increases so much that it exceeds the autoignition temperature of the fuel. When the piston approaches the top dead center (TDC), diesel fuel is injected into the compressed air heated to a temperature of ~600°C. The fuel autoignites and therefore spark plugs are not required.
In a very cold engine, the compressed air may not reach the required temperature. In this case, a preliminary roll-on is used. For this purpose, a glow plug is installed in each swirl chamber of the diesel engine, which heats up the combustion chamber. In addition, the diesel engine is equipped with a cold start accelerator, which is activated using a button on the instrument panel before starting the engine. Under the influence of the cold start accelerator, the injection moment of the high-pressure fuel pump (HPFP) moves towards the advance, thereby fuel is injected earlier into the hot air, the cold engine starts quickly. As soon as the engine reaches its operating temperature, the cold start button must be released again.
The fuel is sucked directly from the fuel tank by the injection pump (IPP). It creates the pressure of about 135 bar required for injection, and distributes the fuel to the individual cylinders according to the firing order. At the same time, the injection pump regulator controls the injection volume depending on the position of the accelerator pedal. At the moment of ignition, the diesel fuel enters the swirl chamber of the corresponding cylinder via the injectors. During the compression stroke, the sucked air takes the form of a swirl flow in the shape of the swirl chamber and is thus optimally mixed with the injected fuel.
Before the fuel reaches the injection pump, it passes through the fuel filter. There it is cleaned of dirt and water. Therefore, it seems necessary to change the fuel filter according to the maintenance recommendations.
The injection pump does not require maintenance. All moving parts of the pump are lubricated with diesel fuel. The pump is driven by the crankshaft through the pump drive shaft in the drive chain box.
Since a diesel engine is a device with spontaneous combustion of fuel, it does not turn off when the voltage in the ignition system is interrupted; for this purpose, it is equipped with an electromagnetic fuel cut-off valve. When the ignition is turned off, the voltage on the electromagnetic valve is disconnected and it closes the fuel supply channel. Its operation can be checked by ear (when the valve is triggered, a click should be heard). When the engine is started by the starter switch, voltage is applied to the valve, thereby opening the fuel channel.
Visitor comments