4-stroke engine: operating principle

The type of power equipment is crucial when choosing. Today there are two options - 4-stroke engine and 2-stroke.

Features

The power equipment works on the basis of expansion of gases at heating which occurs at ignition of the fuel getting in an internal part of the cylinder. Many people are of the opinion that the Briggs Stratton 4-stroke engine has better characteristics. To get an unambiguous answer, it is worthwhile to understand the peculiarities of the work of both types.

Crank-crank design and mechanism responsible for the distribution of gas - this is the main components, no less important systems that provide lubrication of elements, ignition and power.

The crank-crank device transmits the necessary impact of expanding gases, while the mechanism that distributes them supplies gasoline to the cylinder space.

The 4-stroke engine is characterized by economical fuel consumption, the absence of combustible mixtures in the exhaust, a lower level of reproduced noise, and environmental friendliness, which has made it popular with many companies involved in the production of cars.

How the two-stroke engine works

The whole process is based on working progress and compression.

The piston is basically in two positions - the lower and upper dead points. When moving from one to the other, the purge and discharge port alternately overlap, then the gas present in the cylinder begins to contract. At this time, the combustible mixture exits the inlet port and enters the chamber of the crank mechanism, which it will subsequently compress.

After the vapors of air and gasoline reach the maximum degree of compression, the electric spark coming from the candle ignites them. At this time, a pressure is created that facilitates the movement of the piston to the lower point due to a sharp increase in the volume of the gas and the temperature of the mixture. During the movement, the outlet opens and the combustion products exit. The mixture is squeezed when the piston moves and it is in the combustion chamber, at the same time a purging window is opened.

Positive and negative sides

The mechanism is distinguished by a sufficient number of drawbacks, among which high fuel consumption, with most of it wasted. This is due to the partial release of the vapor mixture during the simultaneous opening of the exhaust and purge windows. Also it is necessary to note a continuous oil consumption, since it is a part of the mixture and without it the engine can not work. Another negative side is the continuous preparation of the fuel mixture.

Two-stroke mechanism has a small weight and dimensions, which can not boast a 4-stroke engine. But in the process of using the car it gives more problems, because of what such an option is common in the field of modeling, where special importance is attached to every extra kilogram.

How the four-stroke engine works

It is completely different from its lighter counterpart. The principle of the 4-stroke engine is a cycle consisting of sequential intake, compression, working stroke and exhaustion, due to which the valve system has found its application.

The piston opens the inlet device by moving downwards, then the combustible mixture enters the cylinder, while the working mixture is created after mixing with the residues from the used composition.

Processes that are systematically repetitive, in a set sequence, represent a duty cycle, they occur in all cylinders and provide mechanical work by converting energy.

Advantages

The motor in a conventional car works on the basis of a four-stage cycle, it occurs during four movements of the piston or two crankshaft revolutions.

4-stroke diesel engine has a completely different method of ignition of the working mixture and its formation, compared with the carburettor option. The main difference in the intake stroke, as air enters the diesel cylinder heated to high temperature values, and fuel, sprayed onto the smallest particles, ignites under the influence of the temperature level.

The 4-stroke engine has an oil sump in its design, this part is responsible for the lubricants, more precisely, for a constant stay at the established level. The oil pump transfers the material to the lubrication system and distributes it to the walls of the inside of the cylinder. As a result, the friction of the piston is reduced due to the oil thin film. The oil-removable special ring elements prevent the oil fluid from entering the combustion chamber by means of a back-off. In this case, the oil pump is used, as a rule, in engines with a capacity of more than 5 l / s. In other cases, the lubricant is distributed by oil mist, the creation of which is provided by the crankshaft.

The 4-stroke engine has a lower load, due to this, the oil arrives systematically in the required volume, thereby increasing the life of the mechanism.

During the season, only one lubricant replacement is needed. It is worth noting that you need to periodically check the oil level, although it can not suddenly disappear. Today, manufacturers have simplified the task for drivers and equipped modern models with special sensors that control the level of lubrication and report on the need to replace it.

The main difference

As noted above, two types of motor have a fundamental difference, which consists in the lubrication of two-stroke mechanisms, carried out by a mixture of gasoline and oil, which subsequently burns. Some of them have a special system that supplies oil to the crankcase, but the meaning remains the same - the gasoline burns together with the oil. While the Chinese 4-stroke "Lifan", like any other similar plan, is equipped with devices for returning oil to a special compartment.

Lubricants

In view of the differences in the engines, car oils must meet different requirements:

• Oil for the four-stroke mechanism must have high lubricating properties, which remain the same for a long time;
• For another type, the maximum combustion of the lubricant with minimal residual phenomena in the form of soot and ash is necessary.

At the beginning of the existence of engines, the usual distillation of petroleum products was used to produce lubricants. The composition was the same for both variants. The need to create new oils did not arise due to the fact that the 4-stroke engine had low power, and as a result, little wear and low loads on the components. Later, the reserve of trains was exhausted by a gradual increase in turnover in the process of work and general parameters. This task was solved by the use of additives - special additives for motor oils. Today they significantly increase the characteristics of the lubricant.

Power

There is an opinion that the 2T engines are more powerful due to the full use of fuel energy for two shaft revolutions. This is not quite true, because in this version the cylinder, unlike the other type of motor, has not an integral structure, and its part falls on the exhaust and inlet openings, respectively, the smaller volume of fuel burns.

The simplicity of the 2T mechanism resulted in the use of a mixture of gasoline and oil as a lubricant. A working mixture with a lubricant content is characterized by a lower energy release. Also, structural features led to an empty consumption of the combustible mixture, which accounts for a fairly large part. At the same time, the 4-stroke Chinese engine has a more complex design, and as a result, a small amount of non-combustible fuel. That is, the 2T motors are more powerful only in a fairly narrow range.