In a diesel engine, clean air is sucked into the cylinders and compressed to a high pressure, reaching the ignition temperature of diesel fuel. When the piston approaches TDC, diesel fuel is injected into the cylinders under high pressure, which ignites spontaneously.
When the engine is cold, the temperature of the compressed air does not reach the ignition point of the fuel. In this case, the cylinders must be preheated. For this purpose, glow plugs are located in the vortex chambers of the cylinders. In addition, the diesel engine has a starting device that sets the injection advance controller in the high pressure fuel pump (injection pump) for an earlier injection. As a result, the fuel is injected into the hot air earlier and the cold engine starts better. As soon as the temperature in the cylinders reaches the value required for the ignition of the fuel, the starting device automatically turns off.
The fuel is sucked in by the injection pump directly from the fuel tank and is supplied at a pressure of about 135 bar. It is distributed among the cylinders in the order in which they operate.
The amount of fuel injected is controlled by the accelerator pedal. Fuel is supplied at the right time to the vortex chamber of the corresponding cylinder and sprayed by a nozzle. The swirl chamber is shaped so that the air is optimally mixed with the injected fuel.
Before fuel enters the injection pump, it passes through the fuel filter, being cleaned of contaminants and water. The filter must be replaced in a timely manner.
The injection pump does not require maintenance. All moving parts of the pump are lubricated with diesel fuel. The pump is driven by a toothed belt, which also drives the camshaft. Since the diesel engine does not have an ignition system, it cannot be shut down by disconnecting the high voltage from the spark plugs (like a gasoline engine). To stop the engine, a special solenoid valve is provided, which, when the ignition is turned off, closes the fuel supply channel.
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