Thermal expansion of gases is used today in many devices. These are turbojet engines, and diesel engines, and carburetors … The thermal unit can be of two types:
- external combustion engine;
- ICE (internal combustion engine).
Let's consider the device of the second type in detail.
General characteristics
Most cars today are equipped with such devices, where the principle of the internal combustion engine is to release heat and convert it into mechanical work. This process is carried out in cylinders.
The most economical options are piston and combination motors. They can be used for a long time and are relatively small in size and weight. But the downside in them is the movement of the piston, which occurs in a reciprocating manner with the participation of a crank mechanism, which, on the one hand, makes the work more difficult, and on the other hand, is a limiter in increasing the speed. The latter is most noticeable with large motor dimensions.
The creation, development and, in general, the operation of an internal combustion engine, of course, are based on the effect of thermal expansion, within which heated gases perform useful work. As a result of combustion, the pressure in the cylinder jumps sharply, and the piston moves. This is the principle of force action, which performs thermal expansion, which is used in internal combustion engines and other technologies.
In order for usable mechanical energy to be continuously produced, the combustion chamber must be replenished with an air-fuel mixture, due to which the piston drives the crankshaft, and the latter drives the wheels.
Most cars today are four-stroke, and the energy in them is almost completely converted into useful energy.
A bit of history
The first mechanism of this type was created in 1860 by a French engineer, and two years later, his compatriot proposed the use of a four-stroke cycle, where the operation of an internal combustion engine included the processes of suction, compression, combustion and expansion, as well as exhaust.
In 1878, a German physicist invented the first four-stroke engine with an efficiency of up to 22%, which greatly exceeded the performance of all predecessors.
Such a motor began to become widespread in various spheres of life. Today it is used in automobiles, agricultural machinery, ships, diesel locomotives, aircraft, power plants and so on.
Pros and cons
Success is mainly due to the practical characteristics ofeconomy, compactness and good adaptability. In addition, the engine is able to start in the most normal conditions, after which it quickly accelerates and reaches full load. For vehicles, such a characteristic as a significant braking torque is important.
ICE (engine) is able to run on different types of fuel, from gasoline to fuel oil.
However, these motors also have a number of disadvantages, among which are limited power, high noise, very frequent rotation of the crankshaft at start-up, inability to connect to the drive wheels, toxicity, piston reciprocating movements.
Case
The body is a classic design, consisting of a cylinder block, their head, and in the case of a split lower part of the crankcase, and a fundamental frame with covers. There is also a monoblock design. Such diversity, of course, implies a different approach to repair.
The elements of the motor housing are the base where parts of the timing and crank mechanism, cooling systems, power supply, lubrication and so on are attached.
Classification
The most widely used internal combustion engine (ICE), in which the process takes place in the cylinders themselves. But motors can be classified according to various other criteria.
According to the working cycle they are:
- two-stroke;
- four-stroke.
According to the way the mixture is formed in the internal combustion engine, the engine is:
- with externalformation (gas and carburetor);
- engine with internal mixture formation (diesel).
By cooling method:
- with liquid;
- with air.
By cylinders:
- single-cylinder;
- two-cylinder;
- multi-cylinder.
By their location:
- row (vertical or oblique);
- V-shaped.
By filling the cylinder with air:
- naturally aspirated;
- supercharged.
According to the frequency of rotation of the internal combustion engine (engine) it happens:
- slow-moving;
- increased frequency;
- fast moving.
By fuel used:
- multi-fuel;
- gas;
- diesel;
- petrol.
By compression ratio:
- high;
- low.
For purpose:
- autotractor;
- aviation;
- stationary;
- ship and so on.
Power
The power of automobile units is usually calculated in horsepower. This term was introduced in the late eighteenth century by an English inventor who followed horses pulling baskets of coal from mines. By measuring the weight of the load and the height to which it is raised, D. Watt calculated how much coal a horse can pull in a minute from a certain depth. Subsequently, this unit was called the well-known term "horsepower". After in 1960 there wasadopted International System of Units (SI), h.p. became an auxiliary unit, which is equal to 736 W.
