When starting a very cold engine, it is not possible to reach the auto-ignition temperature only due to the compression ratio. In this case, a fresh charge must be preheated. To do this, a glow plug is installed in each vortex chamber, which heats the charge.
In addition, the diesel engine has a temperature controller that moves the injection advance clutch piston in the injection pump in the advance direction. Thanks to this, fuel is injected into the hot air earlier, and the cold engine starts faster. When the engine reaches operating temperature, the thermostat automatically returns the clutch piston back.
Fuel is sucked from the fuel tank directly by the fuel injection pump of the distribution type. In the injection pump, a high pressure of approximately 130 bar is created, which is necessary for the implementation of the diesel process, and the fuel is distributed to the individual cylinders in accordance with the order of their operation. At the same time, the regulator in the injection pump changes the cyclic fuel supply in accordance with the position of the accelerator pedal. Through the injectors, diesel fuel with a given advance angle is injected into the swirl chambers of the corresponding cylinders. Due to the shape of the prechamber or swirl chamber, the air entering the cylinder receives a certain vortex motion during compression, which creates optimal conditions for mixing the injected fuel and air.
Before fuel enters the injection pump, it passes through the fuel filter. In the filter, dirt and water are retained. Therefore, it is extremely important to remove the water from the filter in a timely manner and replace the filter element in accordance with the maintenance instructions.
HPF does not require maintenance. All moving parts of the pump are lubricated with diesel fuel. The drive of the high-pressure fuel pump, as well as the camshaft, is carried out by a chain. Since the diesel engine self-ignites the fuel-air mixture, and it cannot be stopped by turning off the ignition, a solenoid valve is installed on it that blocks the fuel supply channel. When the ignition is turned off, the voltage supply to the valve stops and the valve closes the fuel channel. This ensures that the fuel supply is interrupted before the steering lock is locked. When the ignition is turned on to start the engine with a starter, voltage is applied to the solenoid valve, and it opens the fuel channel. When the engine is started, the anti-theft system unlocks the solenoid valve, allowing the engine to start. About the anti-theft system see p. 154.
Vehicle operation in winter
With a decrease in ambient temperature, the fluidity of diesel fuel decreases due to the crystallization of the paraffin contained in the fuel. Diesel fuel becomes thick as honey. For this reason, additives are added to diesel fuel at oil refineries in winter, which increase its fluidity and allow the engine to start up to a temperature of -20°C. On models of vehicles manufactured since 9/93, there is also an electric heater in front of the fuel filter, which is automatically switched on by a thermal switch at temperatures below 0°C. At the same time, in the event of a malfunction, the thermal switch protects the fuel from possible overheating.
However, these additives are not always sufficient for normal operation, so diesel engines of cars are equipped with electrical heating. Thanks to this, crystallization of diesel fuel is prevented even in extreme frost. Heating is switched on at temperatures below +6°С after starting the engine and switched off at temperatures above +16°С. This ensures reliable operation of the vehicle at all temperatures.
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