Comparative analysis of the advantages and disadvantages of two stroke and four stroke diesel engine

Two-stroke internal combustion engines have the following advantages compared to four-strokes:

1) Improve the workmanship ability of diesel engine.

2) Improved the dynamics of the diesel engine.

3) The structure of the diesel engine has been simplified.

The following disadvantages: 1) Poor ventilation starting quality and thermal efficiency.

What are the differences between a two-stroke and a four-stroke engine? Do you understand after reading it?

Four-stroke is divided into 4 stages: air intake, compression, work, and exhaust.

Two-stroke: First stroke: The piston goes from top dead center to bottom dead center. Complete two actions.

1.The spark plug ignites, and the work is done – exhaust.

2.The intake air is closed and the air mixture is pressed from the lower part of the piston into the crankcase, and from the upper part of the piston to the cylinder.

Second stroke: The piston goes from bottom dead center to top dead center. Complete two actions.

Turn off all intake and exhaust air and compress the mixture.

Every two strokes complete the work, so it is called a two-stroke.

Advantages: simple structure, small size, light weight, low cost; Stable work, low vibration; Fast acceleration over short distances.

Disadvantages: high fuel consumption (lubricating oil, gasoline); high temperature and high pollution; The exhaust is noisy.

Similarities: both have diesel pumps and oil nozzles, both of which are ignited by compression.

The difference is that the two-stroke has more scavenging pumps, the two-stroke diesel engine cylinder stroke is much more than the four-stroke, the two-stroke cylinder has an additional air intake hole (some are two), and the two-stroke has more horsepower under the same displacement.

Here's a brief introduction to two-stroke diesel engines:

In a four-stroke diesel engine, the piston travels four strokes to complete a working cycle, two of which are strokes (intake and exhaust), and the piston functions as an air pump. In the two-stroke diesel engine, every revolution of the crankshaft, that is, the piston completes a working cycle every two strokes, and the intake and exhaust process is completed by using a part of the compression and working process, so the piston of the two-stroke diesel engine does not have the role of an air pump, in order to eliminate the exhaust gas after combustion, and fill the cylinder with fresh air, a special scavenging pump (supercharger) must be installed on the diesel engine.

Here's how a two-stroke engine works:

First stroke – The piston moves from the bottom dead center to the top dead center.

When the piston is at the bottom dead center, the exhaust valve and the air inlet hole have already been opened, and the compressed air in the air storage chamber L enters the cylinder and rushes to the exhaust valve, which produces the effect of removing the exhaust gas, and also fills the cylinder with fresh air. When the piston moves from bottom dead center to top dead center, the air inlet hole is first closed by the piston, and then the exhaust valve is also closed; The air is compressed inside the cylinder.

Second stroke – The piston moves from top dead center to bottom dead center.

Before the piston travels to the dead center, the injector injects fuel into the combustion chamber, and the high temperature generated by the compressed air immediately ignites the atomized fuel, and the pressure generated by the combustion pushes the piston down until the exhaust valve is opened again. After combustion, the exhaust gas is discharged from the exhaust valve by itself under the action of the internal and external pressure difference. When the air inlet is opened by the piston, the cylinder is scavenged.

Every time the crankshaft turns, the piston goes two strokes to complete a cycle, so it is called a two-stroke diesel engine.

One- and two-stroke engines:

Advantages: The two-stroke engine does not have intake and exhaust valves, does not have a complex valve mechanism and lubrication system, and the cooling system is generally air-cooled, so it is simpler in structure than the four-stroke engine, relatively light in weight, and has a manufacturing cost.

Low cost, failure rate.

It is also lower and easier to maintain.

Disadvantages: The intake and exhaust process of the two-stroke engine only occupies the crankshaft.

The angle of 130 ° 150 °, the intake and exhaust processes are carried out almost simultaneously, and the use of new gas to sweep away the exhaust gas, there will inevitably be some fresh mixed gas flowing out of the exhaust port with the exhaust gas, and the exhaust gas is not easy to clean. Therefore, the air exchange quality of the two-stroke internal combustion engine is poor, the fuel efficiency is not high, and the fuel consumption of the whole vehicle is relatively high.

2. Four-stroke engine:

Advantages: Since the intake and exhaust of the four-stroke engine are independent, the intake and exhaust efficiency is high, the combustion is sufficient, and the economy is fuel-efficient. Due to the intake and exhaust mode, the stroke of the piston can be designed to be longer than that of the two-stroke, and the output at medium and low speeds is much larger than that of the two-stroke, so that it can carry more pulp to produce greater pulling force.

And under light and heavy load conditions, the output can be consistent.

Disadvantages: Four-stroke engines work every two weeks. So the power of an engine of the same displacement is less than that of a two-stroke. According to the technical parameters provided by the manufacturer and the general opinion, the power of the four-stroke engine is equivalent to 60% of that of the two-stroke.

Summary. The lubrication system of the two-stroke engine is relatively simple and rough, and the four-stroke engine is as precise as the lubrication, and the long-term use of the two-stroke engine causes the wear of the engine components to be greater than that of the 4-stroke engine, so in terms of engine operation durability, the 2-stroke engine is not as good as the 4-stroke engine. Due to the structural disadvantages of the 2-stroke engine lubrication system, the lubrication effect for the lubricating oil is higher, which also means that the 2-stroke engine will be more expensive in terms of lubricating oil cost than the 4-stroke engine.

Gasoline engines come in two-stroke and four-stroke, which is more durable?

Hello, glad to answer for you, four-strokes are more durable.

The two-stroke engine lubrication system is relatively simple and rough, and the four-stroke engine is as precise as the four-stroke engine, and the long-term use of the two-stroke engine causes the wear of the engine components to be greater than that of the 4-stroke engine, so the 2-stroke engine is not as good as the 4-stroke engine on the surface of the collapse of the engine operation durability. Due to the structural disadvantages of the 2-stroke engine lubrication system, the lubrication effect for the lubricating oil is higher, which also means that the 2-stroke engine will be more expensive in terms of lubricating oil cost than the 4-stroke engine.

1: Four-stroke diesel engine, working process: suction - compression - expansion - exhaust, a total of 4 strokes, the crankshaft rotates 2 times.

Two-stroke diesel engine, working process: suction compression-expansion exhaust, a total of 2 strokes, crankshaft rotation 1 turn.

That is, with the same displacement, the power emitted by a two-stroke is theoretically twice that of a four-stroke.

2: Four-strokes are mostly medium and high-speed machines. Two-strokes are mostly low-speed machines.

In addition, the structure such as the air scavenger and the turbocharging arrangement are also different.

Hope it helps!

Hello, the 4-stroke gasoline engine must be better than the 2-stroke gasoline engine, because the 4-stroke gasoline engine has low noise and low exhaust emission pollution, and the gasoline can be fully burned when the gasoline engine is working, and the exhaust gas is not very strong gasoline smell, and the 2-stroke gasoline engine is noisy and the exhaust emission is serious, and the gasoline can not be fully burned during work, so the fuel consumption will naturally be high, and the energy source is wasted, which is not a low-carbon environmental protection leniency.

Hello, the similarities and differences between four-stroke diesel engines and two-stroke diesel engines are as follows: Similarities: 1

Both are internal combustion engines, which generate power through fuel combustion. 2.All are diesel engines, using diesel as fuel.

3.It is composed of cylinder block, piston, connecting rod, crankshaft and other components. Differences:

1.The working principle is different: the one-time cycle of a four-stroke diesel engine includes four stages: intake, compression, combustion and exhaust, while the one-cycle of a two-stroke diesel engine only has two stages: intake and compression.

2.The emission pollution is different: the four-flush Yancheng diesel engine can achieve lower emission standards due to the net hall weighing system after combustion; The two-stroke diesel engine has high emission pollution due to the lack of a purification system.

3.The power output is different: the power output of a four-stroke diesel engine is relatively smooth, while the two-stroke diesel engine has a stronger power output at high speeds.

With the continuous improvement of environmental awareness, four-stroke diesel engines have gradually replaced two-stroke diesel engines and become the mainstream of diesel engines. At the same time, with the continuous progress of science and technology, the emission pollution of diesel engines is also decreasing.

Hello, diesel engines can be divided into four-stroke and two-stroke, and the similarities and differences between them are described below. 1.Working principleThe working principle of four-stroke diesel engine and two-stroke diesel engine is basically the same, both of which use compressed air to make the fuel spontaneously ignite at high temperature and high pressure, and promote the piston movement to complete the work.

The difference is that a four-stroke diesel engine completes one cycle with four working strokes, while a two-stroke diesel engine only needs two working strokes. 2.In the working process of the four-stroke diesel engine, from the intake to the exhaust, it takes four strokes:

Air intake, compression, combustion, exhaust. Whereas, a two-stroke diesel engine only needs two strokes: compression and combustion.

3.The compression ratio of a four-stroke diesel engine is generally larger, usually above 16:1.

Whereas, the compression of a two-stroke diesel engine is relatively small, usually around 14:1. 4.

The power take-off four-stroke diesel engine has a relatively smooth power delivery due to the fact that each stroke has its own working time, which allows for better use of the power output. Whereas, the power take-off of a two-stroke diesel is relatively abrupt because its two strokes need to be completed in a shorter time. 5.

Maintenance and durability Due to the simple structure, the maintenance of a two-stroke diesel engine is easier than that of a four-stroke diesel engine. At the same time, two-stroke diesel engines have a lower number of components, so they have higher durability.

Four-stroke diesel engine and two-stroke gasoline engine are both common types of internal combustion engines, although they have certain differences in working principles and structural design, but they also have many things in common, and the following are their similarities and differences:

1.The working principle is different: the four-stroke diesel engine adopts the compression-ignition ignition method, and the piston movement is driven by high-pressure gas to complete the reciprocating motion; The two-stroke gasoline engine uses a spark ignition method to promote the piston movement through **.

2.The type of fuel is different: a four-stroke diesel engine uses diesel, while a two-stroke gasoline engine uses gasoline.

3.The number of cylinders is different: In general, a four-stroke diesel engine has more cylinders than a two-stroke gasoline engine.

4.Different power output: Since diesel has a higher calorific value than gasoline and the supercharging method allows for better use of fuel, the output power of a four-stroke diesel engine is higher for the same volume. The two-stroke gasoline engine has a certain advantage in terms of speed.

5.Different emission standards: Since diesel combustion produces more exhaust pollutants than gasoline, four-stroke diesel engines are relatively high in national emission standards.

In short, four-stroke diesel engines and two-stroke gasoline engines have their own advantages and disadvantages, and choosing different engine types in different use scenarios can better meet the needs of users.