Piston DVZ (internal combustion engine) is a heat engine and works on the principle of combustion of a mixture of fuel and air in the combustion chamber. The main task of such a device is to convert the energy of combustion of fuel charge into useful mechanical work.
Despite the general principle of operation, today there are a large number of units, which differ significantly from each other due to a number of individual design features. In this article we will talk about that, what are internal combustion engines, as well as what are their main features and differences.
Types of internal combustion engines
Let's start with that, that the internal combustion engine can be two-stroke and four-stroke. As for car engines, these units are four-stroke. Engine stroke cycles are:
- intake of fuel-air mixture or air (depending on the type of internal combustion engine);
- compression of a mixture of fuel and air;
- fuel charge combustion and operating stroke;
- release of exhaust gases from the combustion chamber;
They work like gasoline on this principle, and diesel reciprocating engines, which are widely used in cars and other equipment. It is also worth mentioning gas units, in which gaseous fuel is burned similarly to diesel or gasoline.
Gasoline power units
As for reciprocating gasoline engines, such engines have an ignition system to ignite the working mixture from the spark. Power supply systems in such units can be carburetor or injector (injection).
Preparation of the working mixture in the carburetor internal combustion engine takes place in the carburetor, then mixed gasoline and air are fed into the intake manifold. Today, such systems are considered obsolete, as they are not able to provide the engine with proper environmental friendliness and economy.
Injection engines by type of power system design are monoinjector (mono prisk) or distributed injection systems. In the first case, the scheme provides for the presence of only one nozzle, which injects fuel into the intake manifold. Distributed injection solutions have a separate nozzle for each cylinder, which is installed next to the intake valves.
Such a power system, particularly distributed injection, allows you to increase engine power, this achieves fuel efficiency and reduces the toxicity of exhaust gases. This was made possible by the precise dosing of the fuel supplied under the control of the ECM (electronic engine management system).
Further development of fuel supply systems led to the emergence of direct current engines (direct) injection. Their main difference from their predecessors is that, that air and fuel are supplied to the combustion chamber separately. In other words, the nozzle is not installed above the intake valves, and is mounted directly in the cylinder.
This solution allows you to supply fuel directly, and the feed itself is divided into several stages (post-injection). As a result, it is possible to achieve the most efficient and complete combustion of fuel, the engine is able to run on a lean mixture (example, motors of the GDI family), fuel consumption is reduced, reduced exhaust toxicity, etc.. d.
Diesel engines
The diesel engine runs on diesel fuel, and also differs significantly from gasoline. The main difference is the lack of a spark ignition system. Ignition of a mixture of fuel and air in a diesel engine comes from compression.
If simple, first the air is compressed in the cylinders, which is very hot. At the last moment, diesel fuel is injected directly into the combustion chamber, then the heated and strongly compressed mixture ignites on its own.
If you compare diesel and gasoline engines, diesel is more economical, best efficiency and maximum torque, which is available at low revs. With that in mind, that diesels develop more traction at lower crankshaft speeds, in practice, such a motor does not need to be "twisted" at the start, and you can count on a confident pick-up from the "bottom".
However, in the list of disadvantages of such units can be identified sensitive fuel system, as well as more weight and lower speeds in maximum speed. The point is, that the diesel is initially "slow" and has a lower crankshaft speed compared to gasoline engines.
Diesels are also more massive, as features of ignition from compression provide more serious loadings on all elements of such unit. In other words, parts in the diesel engine are stronger and heavier. Diesel engines are also noisier, due to the process of ignition and combustion of diesel fuel.
Rotary engine
Wankel engine (rotary-piston engine) is a fundamentally different power plant. Pistons are familiar in such an internal combustion engine, which carry out reciprocating movements in the cylinder, simply missing. The main element of a rotary motor is the rotor.
The specified rotor rotates on a given trajectory. Rotary internal combustion engines are petrol, as such a design is not able to provide a high degree of compression of the working mixture.
The advantages include compactness, more power with a small working volume, as well as the ability to spin quickly to high speeds. As a result, cars with such internal combustion engines have outstanding acceleration characteristics.
If we talk about the cons, it is necessary to allocate noticeably reduced resource in comparison with piston units, as well as high fuel consumption. The rotary engine is also highly toxic, that is, it does not quite fit into modern environmental standards.
Hybrid engine
The hybrid power unit is actually a combination of a piston petrol or diesel internal combustion engine and an electric motor.. There is also a traction battery in the design, which feeds the electric motor.
The hybrid works on the principle of maximum fuel economy, that is, the internal combustion engine is activated only in certain modes. When driving quietly, the motor rotates, and the internal combustion engine is connected then, when the battery is discharged, intensive acceleration of the vehicle is required, loads are quite high t. P.
The energy recovery scheme is also actively used during the operation of the hybrid unit. Example, the generator runs during engine braking, which charges the traction battery. This combination of two types of power plants allows to improve the acceleration dynamics (especially when the internal combustion engine and the electric motor are involved at the same time), there are significant fuel savings and low emissions.
Layout and technical characteristics of the internal combustion engine
It is worth adding, that there are many types of internal combustion engines, which differ from each other in the layout and location of the cylinders.
The point is, that the space in the engine compartment is limited, at the same time on different cars there is a need to contain in such space the unit with this or that quantity of cylinders.
Usually, by layout on most machines can often be found:
- in-line engine;
- V-shaped motor;
- opposite engine;
In-line engine means, that all its cylinders are located in one plane. In-line "fours" (4-x cylinder engine) is the most common type of internal combustion engine. In-line "sixes" are also quite popular, they vibrate less, have acceptable power, however, such an engine is quite long.
Another option is a V-shaped engine. The cylinders in this engine are located in two planes, reminiscent of the letter "V". It has a similar internal combustion engine 6 or 8 cylinders (V6 or V8), while the length of the engine compared to an in-line engine is less, although the width naturally increases. We will add, that the angle between the planes is called the angle of collapse.
The opposition engine also deserves special attention. Notable, that such an arrangement implies a collapse angle 180 degrees. Actually, cylinders and pistons are opposite each other, and the unit itself is called "boxer". This arrangement allowed to reduce the height of the opponent, reduce vibration, improve weight, etc.. d.
Let's add, that there are so-called VR engines. Their feature is a small angle of collapse, allowing to reduce the sizes of the internal combustion engine in length and width. Also worth mentioning are the powerful W-engines. These power units are multi-cylinder (example, W12) regarding layout, the design may include three rows of cylinders at once, which are located at a large angle of collapse.
We also recommend reading the article about it, what is the opposite engine. In this article you will learn about the design features, as well as the main advantages and disadvantages of motors of this type.
Another option is to arrange the same three rows of cylinders, while the angle of collapse is minimized (as in the case of VR-layout). Usually, the last variant got accustomed to powerful cars of a class "premium", sports cars and solid SUVs. The point is, that even with so many cylinders, the engine is still compact.
The main technical parameters of the internal combustion engine
Internal combustion engines also have a number of characteristics and parameters, which are laid down constructively. If simple, we are talking about the working volume, degree of compression, power and torque, etc.. d.
The greatest interest for the average person, of course, there is power and torque. Torque, which is created on the crankshaft, actually indicates that, what traction force will be transmitted to the wheels.
Naturally, the greater the torque, the greater the traction. In other words, acceleration dynamics depends on this indicator. As for engine power, this is the value, which reflects the work done per unit time.
There are two ways to increase torque and power:
- larger working volume;
- burning more fuel-air mixture;
If simple, in the first case, it is a physical increase in the combustion chamber and the volume of the cylinders. The second refers to the forced supply of air to the cylinders under pressure to burn more fuel.
Usually, powerful engines with a large volume of atmospheric, that is, "suck" the outside air into the cylinders themselves due to the vacuum from the movement of the pistons. Powerful units, at the same time have a smaller volume, are equipped with mechanical compressors or turbocharging. In such internal combustion engines air is forced, that is, enters the combustion chamber under pressure.
As a result
As you can see, the above material gives a general idea, which are internal combustion engines. At the same time, even taking into account the general principle of operation, power units can differ significantly in such indicators, as a layout, power, torque, fuel consumption, etc.. d.
We also recommend reading the article about it, what is a GDI engine. In this article you will learn about the design features, principles of work,as well as the pros and cons of motors of this type.
Moreover, even engines, similar in design (example, in-line four-cylinder engine), may have different numbers of inlet and outlet valves per cylinder (example, 8-and and 16-valve engines).
On some internal combustion engines the system of change of phases of gas distribution in a complex with turbocharging is used for reception of necessary power, while others with exactly the same workload and layout do not have such solutions.
For this reason, to objectively assess the performance of an engine at different speeds, and not on the crankshaft, but on wheels, it is necessary to carry out special complex measurements on the dynamometer stand.