Eight characteristics of two-stroke gasoline saw engine

by:Jiali     2020-06-28
As an indispensable garden machine in comprehensive operations such as forest harvesting, timber production, and tree branching, chain saws are widely used in landscaping, forest fire prevention, wood processing, furniture manufacturing, and construction engineering. There are three main types of chain saw engines : External combustion engine, internal combustion engine and electric motor. External combustion engine and internal combustion engine are all converted into mechanical energy by the heat energy released when the fuel is burned. They are collectively referred to as heat engines. The engine of the chain saw is a two-stroke engine. The engine is different from the engines commonly used in automobiles and tractors. The following is a brief introduction to the eight characteristics of the chain saw engine for the majority of chain saw users. 1. The chain saw engine generally adopts a high-revolution two-stroke gasoline engine. This engine is very similar to the 'small engine' (starting engine) on the Dongfanghong tractor and 40 skidder tractor engines, and is also similar to the engine on small motorcycles. The power of the chain saw engine is generally 3-5 horsepower or more, and the crankshaft revolutions per minute can reach 5000-8000 revolutions. 2. Since the crankshaft of the two-stroke engine can complete one working cycle every revolution, the four-stroke engine needs two weeks. In theory, when other conditions are the same, the power of a two-stroke engine is double that of a four-stroke engine. Because the two-stroke gasoline engine needs to lose some fuel in the intake and exhaust process, as well as other reasons, its actual power is only 50-60% larger than that of the four-stroke engine. 3. Since the two-stroke engine is adopted, the valve mechanism is omitted, the body is simplified, the structure is simple, the volume is small, the weight is reduced, and the price is cheaper. Due to the complex structure of the four-stroke engine, the volume and weight are relatively large and the price is expensive. 4. Since there is no special mechanism to complete the gas distribution, its accuracy is worse than that of the four-stroke engine, and the fuel loss is large. Some of the fuel (mixed gas) runs away with the exhaust gas. The carburetor has a simple structure and cannot be effectively adjusted according to the engine. The difference in load automatically adjusts the oil supply and air intake, so the fuel consumption is very large. 5. The four-stroke engine relies on the inertial splash of the oil pump and crankshaft to lubricate the entire engine. The oil in the two-stroke engine only lubricates the transmission mechanism. The cylinder, piston and crankshaft rely on a separate oil tank through the oil pump or manual to mix the oil into gasoline The internal combustion is carried out at the same time, and the purpose of lubricating the relevant parts is achieved at the same time, so the two-stroke engine will emit blue smoke, while the four-stroke engine does not emit smoke under normal conditions. 6. The weight of the flywheel can be smaller due to the use of the high-speed machine, so the weight is reduced accordingly. However, due to the high number of revolutions, the friction between the rotating parts and the sliding parts is increased, which requires the use of higher-grade wear-resistant materials to manufacture various parts, which increases the complexity of the manufacturing process. For example, in order to increase the hardness of the cylinder wall, it needs to be hardened, and it needs special bearings that can withstand the work of high revolutions. 7. When two-stroke and four-stroke internal combustion engines complete the same working cycle, their crankshaft revolutions differ by a factor of two. That is to say, every two revolutions of the crankshaft, the piston of a two-stroke internal combustion engine is subjected to more pressure of the combustion gas than the piston of a four-stroke internal combustion engine. Therefore, from this perspective, the rotation of the two-stroke internal combustion engine is more balanced. 8. Under the same conditions, the two-stroke engine speed is higher and the heat of the cylinder is greater, so its heat sink is also made larger. The two-stroke engine has higher noise and vibration, and the four-stroke engine has lower noise and vibration. Finally, remind everyone to pay attention to that the oil of the two-stroke engine and the four-stroke engine of the chain saw cannot be mixed. Two-stroke chain saws with four-stroke oil will cause serious carbon deposits on the top of the spark plug and shorten life. There is serious carbon deposition inside the combustion chamber, which will wear moving parts like abrasives.
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