Two-stroke engine. Principle of operation

Today, few people are surprised by such an invention as an internal combustion engine. Millions of various devices use them for their functioning. An invention of this type appeared in the 19th century, and it was due to the necessity of creating a modern and effective mechanism that could drive the technical devices. Initially, it had many shortcomings, and the efficiency was extremely low. Subsequently, it underwent a variety of changes, has been improved and now we have the opportunity to use this invention. Including it is used in the design of the motorcycle.

The two-stroke engine, as well as any other engine, is the heart of technology. Regardless of the type, its primary task is to ensure the movement of the mechanisms connected to it. Almost everyone knows how it looks and where it is installed, but how it works, understand not all. Let's try to figure it out now.

The engines of modern motorcycles have a number of differences and the main ones are:

• Method for performing a duty cycle

There are four- and two-stroke engines. The latter differ by almost twice the power with the same volume of cylinders with a four-stroke analog. But this advantage is considered very conditional. First, they have a relatively low efficiency. Therefore, they are used in conditions where low weight, size and unimportant economy is required in fuel consumption. This makes such units ideal for use in motorcycles, light motor boats, gasoline pumps, chainsaws, etc.

• Cooling method

The engine can be air-cooled or liquid-cooled. In view of the small size, the two-stroke engine is most often supplied with air cooling. In its design, everything is aimed at minimizing its weight.

• Scope

A large volume provides for a larger power reserve.

Four-cycle engines are popular, economical, productive, but in motorcycles more often two-stroke engines are used. This preference is primarily due to the simplicity of the motor design, its low weight, low fuel consumption. Negative point is connected with the fact that the filling of the combustible mixture is insufficient. This nuance is associated with poor cleaning of the cylinders from the exhausted mixture of gases.

The principle of the two-stroke engine is based on a short operating cycle, which occurs in one revolution of the crankshaft.

During the movement upwards from the bottom dead center (BDC) to the top dead center (TDC), the piston creates a vacuum, which provides fuel and air mixture to the crankcase. At this point in the combustion chamber, the fuel (working mixture) is compressed. Then, at the top dead center, the working mixture lights up and, expanding, moves the piston down into the NMT.

The modern two-stroke engine differs little from its predecessors, therefore the scheme for supplying a fresh fuel mixture and the withdrawal of processing takes place approximately equally in these units.

Now consider another option - the engine with a valve "plate" type.

During the movement of the piston downward in the crankcase, the pressure increases, which helps to close the poppet valve. At this time, the piston ensures the opening of the exhaust ports, and the spent working mixture in the form of exhaust gases rushes into the receiver. The next action of the movement of the piston towards the NMT is the opening of the purging windows, from which a charge of a fresh working mixture comes in. The two-stroke engine continues its work. The cycle is repeated, ensuring the movement of the motorcycle.

The principle of the two-stroke engine ensures a long service life of the motorcycle, because the system is simple and does not contain a large number of parts. It is resistant to many factors (be it low-quality fuel or oil) and powerful enough to cope with the functions assigned to it.