What is the difference two-stroke engine from four-stroke? The most prominent difference is the modes of ignition of a combustible mixture, which can immediately be seen by sound. The two-stroke motor usually publishes a shrill and very loud hum, while the four-stroke is characteristic of a more calm purring.
Application
In most cases, the difference is also mainly the purpose of the aggregate and its fuel efficiency. In the two-stroke engines, the ignition occurs at every turn crankshaftTherefore, in terms of power, they are twice the four-strokes, in which the mixture is flammable only through turnover.Four-stroke motors are more economical, but harder and more expensive. They are usually installed on cars and special equipment, while on devices such as lawn mowers, motor collections and lung boats, more often are more compact two-stroke models. But gasoline generatorFor example, you can find both two-stroke and four-stroke. may also relate to any type. The principle of operation of these engines is mainly the same, the difference only in the method and efficiency of energy conversion.
What is tact?
Fuel recycling in both varieties of motors is carried out by sequentially performing four different processes known as tactics. The speed with which the engine through these tacts passes is exactly what the two-stroke engine is different from the four-stroke.The first tact is injection. In this case, the piston moves down the cylinder, and the intake valve opens to insert the air-fuel mixture into the combustion chamber. Next comes compression tact. During this tact, the intake valve is closed, and the piston moves around the cylinder up, squeezing the gases there. The working stroke beat begins when the mixture is ignited. At the same time, the spark of the candle flammifies compressed gases, which leads to an explosion, the energy of which pushes the piston down. The last tact is the release: the piston rises up the cylinder, and the exhaust valve opens, allowing you to exit the combustion chamber so that you can start the process again. Returnable piston movements rotate crankshaft, torque from which is transmitted to the working parts of the device. This is where the fuel combustion energy is converted into a translational movement.
The operation of the four-stroke engine
In the standard four-stroke engine, the ignition of the mixture occurs on each second turnover of the crankshaft. Rotation of the shaft drives a complex set of mechanisms that provide synchronous execution of the clock sequence. The opening of intake or exhaust valves is carried out with a cam shaft, which alternates presses the rocker. The valve refund to the closed position is performed using a spring. To avoid the loss of compression, it is necessary that the valves are tightly adjacent to the cylinder head.
The operation of the two-stroke engine
Now let's see what the two-stroke engine from the four-stroke on the principle of operation is different. In two-stroke engines, all four actions are performed in one crankshaft turnover during the piston running from the upper dead point to the bottom, and then back up. The release of exhaust gases (purge) and fuel injection are integrated into one clock, at the end of which the mixture is ignited, and the resulting energy pushes the piston down. This design eliminates the need to use the valve mechanism.Place of valves occupy two holes in the walls of the combustion chamber. When the piston is moving down due to the combustion energy, the outlet opens, allowing the spent gases to exit the chamber. When moving down in the cylinder, there is a vacuum formed, due to which the mixture of air and fuel is drawn through the inlet channel below the inlet canal. When moving up, the piston overlaps the channels and squeezes the gases in the cylinder. At this moment, the ignition candle is triggered, and the whole process described above is repeated again. It is important that in the engines of this type, the ignition of the mixture occurs at each turn, which allows you to extract more power from them at least in the short term.
Mass and power ratio
Two-stroke engines are better suited for devices that require quick and sharp energy bursts, rather than uniform work for a long time. For example, a two-stroke engine accelerates faster than a four-stroke truck, however, it is intended for short-term trips, while a truck can drive hundreds of kilometers before he needs rest. The low duration of the operation of the two-stakeholders is compensated by a low mass ratio to power: such engines usually weigh much less, so faster starts and reach the operating temperature. For their movement, less energy is also required.Which motor is better
In most cases, four-stroke engines can only work in one position, while the two-strokes in this regard are less demanding. This is largely due to the complexity of moving parts, as well as the design of the oil pan. Such a pallet providing engine lubricant is usually present only in four-stroke models and has a huge importance for their work. Two-stroke engines usually do not have such a pallet, so they can be operated in almost any position without the risk of oil flipping or interrupting the lubrication process. For devices such as chainsaws, circular saws and other portable tools, such flexibility is very important.
Fuel efficiency and environmental component
It often finds out that compact and fast engines are more polluted air and consume more fuel. At the bottom point of the movement of the piston, when the combustion chamber is filled with a combustible mixture, a certain amount of fuel is lost, falling into the outlet. This can be seen on the example of the suspended boat motorIf you look closely, you look around it multicolored oily spots. Therefore, these kind engines are considered ineffective and pollutants. environment. Although the four models are somewhat harder and slower, but in them the fuel is completely burned.
Cost of acquisition and maintenance
Smaller engines are usually less expensive, both in terms of initial purchase and in maintenance. However, they are designed for less long. Although there are some exceptions, most of them are not intended for continuous operation for more than a few hours and is designed for not very long term operation. The absence of a separate lubrication system also leads to the fact that even top Motors This type is relatively rapidly wears and come into disrepair due to damage to moving parts.
In part due to the lack of a gasoline lubrication system, designed to fill into a two-stroke motor scooter, for example, you need to add a certain amount special oil. This leads to additional costs and troubles, and can also cause damage (if you forget to fill oils). Motor 4-stroke in most cases requires a minimum of maintenance and care.
Which motor is better
This table briefly describes how the two-stroke motor is different from the four-stroke.What looks younger: the best haircuts for those for those for 30, 40, 50, 60 girls at 20 years old do not worry about the form and the length of the hairstyle. It seems that youth is designed for experiments on appearance and bold curls. However, there is already a post
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