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Pic. 1. Turbocharger: 1 - compressor; 2 - shaft; 3 - turbine
The turbocharger consists of 3 turbine impellers (pic. 1) and compressor 1 mounted on a common shaft 2. To drive the turbine, the energy of the exhaust gases that rotate its blades is used. The rotation of the turbine drives the compressor, which, in turn, compresses and supplies air from the atmosphere into the engine cylinders. The speed of the turbocharger rotor does not depend on the speed of the engine crankshaft, since they do not have a rigid connection between them.
The turbocharger is a precision assembly operating under conditions of high temperatures and dynamic loads, so its repair or replacement requires special equipment and high qualifications of the performer. Carry out these works at specialized service stations.
Note. The turbocharger shaft bearings are lubricated under pressure with engine oil from the engine lubrication system. The speed of the turbocharger shaft is very high, so it continues to rotate for a long time even after the engine has stopped, when there is no pressure in the lubrication system. Therefore, to prevent damage to the turbocharger shaft bearings, do not turn off the engine immediately after parking the vehicle. Let it idle for a few minutes so that the turbocharger shaft has time to reduce the speed to a minimum while continuing to lubricate its bearings.
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Pic. 2. Turbocharged engine air supply system: 1 - air filter; 2 – low pressure air supply hose; 3 - boost control valve; 4 - turbocharger; 5 - throttle assembly; 6 - air supply sleeve of cooled charge air; 7 - charge air cooling radiator (intercooler); 8 - air supply sleeve of hot charge air; 9 - air intake
Air entering the air intake 9 (pic. 2), passes through the air filter 1 and enters the turbocharger 4 through the low-pressure air supply hose 2. In the turbocharger, the air is compressed under the action of the rotating compressor wheel and, as a result, heats up. From the turbocharger, the heated charge air, through the air supply sleeve 8, enters the radiator for cooling (intercooler) 7. Cooling the charge air is necessary for two reasons: firstly, hot air can cause detonation; secondly, cold air is denser, so more oxygen enters the engine. In the intercooler, the air is cooled and enters the throttle assembly 5 through the air supply hose 6. In the engine, the air mixes with the required amount of fuel and, having done useful work, enters the exhaust manifold in the form of exhaust gases. Once in the exhaust manifold, the exhaust gases meet the turbine wheel of the turbocharger on their way and, rotating it, go into the exhaust system. Boost control valve 3 is used to relieve excess air pressure created when the throttle valve is closed. When the valve is actuated, excess air that has passed through the turbocharger flows back into the low pressure air supply hose.
Helpful Hints
With a certain skill and care, many malfunctions of the engine and its systems can be quite accurately determined by the color of the smoke coming out of the exhaust pipe. Blue smoke indicates that oil has entered the combustion chambers, and constant smoking is a sign of severe wear of the parts of the cylinder-piston group. The appearance of smoke during regassing, after prolonged cranking by the starter, after long idling or immediately after engine braking, as a rule, indicates wear on the valve stem seals. Black smoke is a sign of too rich a mixture due to a malfunction of the engine control system or injectors. Blue or thick white smoke with an admixture of moisture (especially after the engine has overheated) means that coolant entered the combustion chamber through a damaged cylinder head gasket. If this gasket is severely damaged, the liquid sometimes enters the oil sump, the oil level rises sharply, and the oil itself turns into a cloudy whitish emulsion. White smoke (steam) when the engine is cold in wet or cold weather, this is normal.
Quite often you can see a car standing in the middle of a city traffic jam with an open hood, emitting puffs of steam. Overheat. It is better, of course, not to allow this, often looking at the temperature gauge. But no one is immune from the fact that the thermostat, electric fan may suddenly fail, or coolant may simply leak. If you miss the moment of overheating, do not panic and do not aggravate the situation. Overheating is not as bad as its possible consequences. Never immediately turn off the engine - it will get a heat stroke and, possibly, having cooled down, will refuse to start at all. Stopping, let it run at idle, then the system will continue to circulate fluid. Turn on the heater to maximum power and open the hood. If possible, pour cold water over the radiator. Stop the engine only when the temperature has dropped. But never immediately open the cork of the expansion tank: on an overheated engine, a geyser from under the open cork is provided to you. Take your time, let everything cool down, so you save the health of the machine and your own health.
Almost all instructions for the car contain a recommendation to depress the clutch when starting the engine. This recommendation is justified only in case of starting in severe frost, so as not to waste battery energy on turning the shafts and gears of the gearbox in thickened oil. In other cases, this is just a recommendation so that the car does not move if the gear is switched on due to forgetfulness. This technique is harmful to the engine, since when the clutch is depressed, a significant force is transmitted through it to the crankshaft thrust bearing, and when starting (especially cold) Lubricant doesn't get to it for a long time. The bearing wears out quickly, the crankshaft receives axial play, and starting off begins to be accompanied by strong vibration. In order not to spoil the engine, make it a habit to check the position of the gear lever before starting and start the engine with the parking brake applied, without depressing the clutch unless absolutely necessary.
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