General information about the device of the car
Immediately, we note that we will not talk about the repair and maintenance of a car of a particular brand, whether it is a “Lada” or a “Mercedes”. For this there is a special literature, which, by the way, does not prevent every motorist from having – at least it will help an inexperienced driver to understand what the mechanic is trying to explain to him at the service station.
So why is the car moving at all?
If to speak in a simple way, the car will go only when the wheels start spinning. And the wheels will spin when the engine creates traction on them. Most modern cars use for this thermal energy, which is released during the combustion of fuel.
Therefore, these engines are called internal combustion engines. There are several varieties of these engines, but we will focus on the most common of them – the piston engine.
The basis of piston engines are cylinder and piston. The piston is attached to the oscillating (“reeling”) around the axis of attachment of the rod – the rod. The second end of the connecting rod is mounted on a round neck of the lever – the knee of the shaft, so called – cranked, or crank. The mechanism consisting of a cylinder, piston, connecting rod and crankshaft is called a crank.
At the top of the cylinder is set head. When the piston is in the extreme position in the side of the head, there is a very small space between it and the head of the block – the combustion chamber. If an explosion is made in the combustion chamber, then its energy will find only one pressure element in the cylinder – the piston. The piston tends to fly out of the cylinder with a projectile force, but since it is mounted on the connecting rod, it moves with it.
The other end of the connecting rod will push the lever-knee and turn the crankshaft, using the force of the explosion. Automobile engines can have several cylinders, from two to sixteen, which are located in the cylinder block. The rotation of the shaft is transmitted through the transmission, about which we will speak further, to the propulsion device – the wheels of the car.
The internal combustion engine (it would be more correct to say – an internal explosion) uses an explosion that is quickly compressed 10–15 times in the combustion chamber of a mixture of gasoline, gas or diesel fuel vapors with air. The energy of the explosion is manifested in a sharp increase in pressure in the combustion chamber due to the expansion of gases resulting from the chemical reaction of the explosion.
The mixture of gasoline and air vapor is sucked in by the piston through the intake valve, which opens at the right moment with the cam of the camshaft directly or through additional devices. After the explosion of the work, the products of combustion escape from the cylinder under their own pressure through the exhaust valve, also opened by the rocker, controlled by the same camshaft, and go out through the exhaust system.
The mechanism consisting of valves, rocker arms, camshaft, intake and exhaust pipes and other parts is called a gas distribution system, or a gas distribution mechanism, which is located in the cylinder head.
A mixture of gasoline or combustible gas and air is suitable not for everyone, but in certain proportions, and it is prepared by its simple device – a carburetor (for gasoline) or a mixer (for gas) outside the cylinder. A mixture of diesel fuel and air is prepared directly in the cylinder, for which, after the air is sucked in, fuel is injected with a special device – a nozzle (injector). Some gasoline engines also use fuel injection. The carburetor, fuel pump, fuel tank, piping, fuel and air filters make up the power system.
In diesel engines, nozzles and a high-pressure pump are used instead of a carburetor. In some designs, pump nozzles are used, without a high pressure pump. The combustible mixture of diesel fuel and air itself explodes due to the high temperature resulting from the rapid compression of air by the piston, if the moment of fuel injection is set exactly at the moment of maximum air compression.
The compression ratio in diesel engines is about one and a half times higher than in gasoline engines.
A combustible mixture of gasoline or gas with air is ignited by an electric spark of high voltage applied to the spark plug at the moment of ignition, which is the moment of maximum compression of the combustible mixture.
The spark is prepared by several devices that make up the ignition system – sources of electricity (battery and generator), transistor switch, high voltage coil, distributor, high voltage wires, plugs.
In an engine, the interaction of parts is hampered by friction, which takes power and causes wear to parts. A lubrication system consisting of an oil pump, an oil sump, a filter, and a variety of channels and holes in the parts provides oil to the rubbing surfaces.
The explosion of the combustible mixture causes the combustion chamber to heat up to about 2000 degrees, so the cylinders need to be cooled to a temperature of 80-90 degrees.