A two-stroke engine is an internal combustion engine that completes the complete cycle of one wheel revolution. History of two-stroke engine
History of two-stroke engine
In many sources, the creation of the first internal combustion engine is credited to Gottlio Daimler, while others are thought to be the inventor of Nicholas Otto. However, there is a version that both are wrong. Back in 1858, Belgian Jean Joseph Etienne Lenoir created a two-stroke internal combustion engine on the gas fuel.
Unlike the steam engine, it was simpler and more economical. However, the Belgian engineer's engine was far from perfect. That was proven by Nicholas Otto, introducing his four-stroke engine. His efficiency was much higher than that of the Lenoir motor, and the engine had smaller dimensions. The two-stroke engine has lost popularity, and before the beginning of the 20th century almost completely disappeared.
In Russia, the "Planet" and "Jupiter" bikes are well known in Russia. In Germany, during the Second World, two-stroke engines were actively used in the aircraft industry. In our time, for example, Rotax motors are widely used in small aviation.
With the toughening of the toxicity norms, two-stroke engines have ceased to be considered as power units for civilian transport, but on scooters, snowmobiles, boats and air model sports, that is, where the engines of low volume and weight are required, they are still not competitors.
two-stroke engine
The two-stroke and four-stroke engines are structurally similar. The main difference between them is the principle of gas distribution and that the two-stroke engine cycle is carried out over a single rotation of the crankshaft.
There is no separate gas distribution mechanism in the two-stroke engine. The role of the inlet and outlet valves shall be performed by the holes in the cylinder wall, and the exhaust gases shall be pushed out and drawn into the next portion of the working mixture itself. In the process of gas exchange, the screw-shing chamber is also involved.
The inlet window is used to fill the cylinder with a fuel-air mixture. The second, exhaust window, is used to remove the exhaust gas from the cylinder. It's higher than the intake.
During the first tact, the piston is moving upward, closing the window and then the prom. The fuel mixture is being compressed. At this time, a vacuum shall be created in the screwy chamber which is used to suction the fuel-air mixture from the carburetor to the cavity of the crankcase.
The next tact begins. The spark ignition ignenches a compressed fuel-air mixture. By expanding, the gases are pushing the piston down. As the piston moves downwards, the exhaust window shall be opened and a portion of the gases shall be removed from the cylinder. When the piston is in motion, an excess pressure is created in the chamber. The piston continues to move downward, to the lower dead point, and opens the blowout hole. The filling of the cylinder with a fuel dispenser shall begin. The fresh mixture pushes the remains of the exhaust gas from the cylinder.
The scheme described is typical for carburettors. The work of diesel and injection two motors is different in that the fuel is injected into the combustion chamber through the nozzle, and the clean air is sucked into the chamber cavity.
Advantages and disadvantages of two-stroke engines
The main advantage of two-stroke engines is higher, compared to four-stroke, litre capacity. The case here is that with an equal number of cylinders and the number of revolutions of the crankshaft per minute, each cylinder makes twice more work. At the same time, the actual engine capacity of the two-stroke engine is shorter (it is shorter by the gas exchange processes) and the actual engine capacity is increased by 50 to 60 per cent.
No less important is compactness. Due to this quality, two-stroke engines are widely used not only in small vehicles like snowmobiles but also in garden machinery as well as tools (for example, in chainsaw). Moreover, the absence of a gas distribution mechanism makes the design easier and cheaper to manufacture.
There are two-stroke DFA' s and significant drawbacks. They use more fuel to waste because when opening the exhaust system, a portion of the unburned mixture falls into the exhaust system. The classic two-stroke engine is extremely primitive-the gasoline is mixed with oil in advance, and both of these substances enter the combustion chamber at the same time. This is because it is impossible to organize oil bath in the crater. As a result, the oil, which does not lubricate the walls of the cylinder, burns with the fuel. The two-stroke engine is also significantly smaller, mainly due to the high turnover of the cap. For this reason, only the special quality oil developed for use in two-stroke engines applies to this type of engine. Environmental parameters are also left to be desired: in the exhaust, due to gas distribution, there is a large number of CO and SN.
2-stroke engine operation
In order to lubricate the piston group of a two-stroke engine, it is necessary to add fuel directly to the fuel. And gasoline and oil, before you fill the tank, you have to mix it up. However, some producers remove the owners from this problem by installing a separate oil product. In this case, it is automatically added to the fuel in the desired proportion.
It should not be forgotten that the crankcase is also involved in the gas distribution and shall be hermetically sealed. Therefore, it is necessary to carefully monitor the condition of the gaskets.
