For how much the cylinder pressure of a gasoline engine is lower than that of a diesel engine

Because diesel fuel is compression-ignited... The gasoline engine is powered by a spark plug to generate an electric spark and ignite the gas-oil mixture!

Because diesel fuel is not easy to ignite, the compression ignition test is used! I remember when I was in school, I taught once that I put cotton in the syringe and press the syringe hard, and the cotton burned! That's how diesel works... So it's stressful!

Diesel fuel is not easy to ignite, so compression ignition is used, while gasoline engines use spark plugs to ignite gasoline. Can the pressure of diesel compression ignition be reduced? This is also an important reason for the low noise of gasoline engines.

Because the ignition method of the 2 engines is different.

There are different reasons for the difference in port pressure.

Diesel engines have one more piston ring than gasoline engines.

The viscosity of lubricating oil in diesel engines is higher than that of gasoline engines.

The main thing is that the compression ratio is much higher than that of gasoline.

Generally above 16 (gasoline engine is generally about 9).

Compression ratio: maximum cylinder volume combustion chamber volume.

Gasoline has good evaporation and is easy to mix! Moreover, the ignition system of the gasoline engine is as high as 15,000-20,000 volts, so the compression ratio does not need to be so high! The diesel engine is different, there is no ignition system, and it spontaneously combustifies by compression, so it is necessary to have a sufficient compression ratio to make the diesel fuel reach enough temperature and pressure before it spontaneously combusts!

I studied automobile! Hopefully! Thank you! ~~

The minimum working volume of the cylinder, that is, the total volume above the piston when the piston is at the top dead center, is called the volume of the combustion chamber, which is represented by V c; When the piston is at the bottom dead center, the total volume above the piston, that is, the maximum volume of the cylinder, is called the total volume of the cylinder, which is expressed by V a.

i.e. =v a v c

The compression ratio indicates the degree to which the gas in the cylinder is compressed as the piston moves from the bottom dead center to the top dead center. The compression ratio is one of the important parameters of the engine. The compression ratio of modern automobile engines, gasoline engines are generally 8 11 due to the limitation of detonation.

There is no knock limit for diesel engines, and the compression ratio is generally 12 22.

Parameter application. Performance metrics.

Compression ratio The compression ratio has a lot to do with engine performance, we all know that when the gasoline engine is running, it is usually the mixture of gasoline and air that is sucked in, and the piston goes up in the compression process, in addition to squeezing the mixture to reduce its volume, two phenomena of vortex and turbulence also occur. When the gas in a closed container is compressed, the pressure increases as the temperature increases. If the compression of the engine is relatively high, the cylinder pressure and temperature generated during compression are relatively increased, the gasoline molecules in the mixture can be vaporized more completely, and the particles can be more fine, coupled with the vortex and turbulence effect just mentioned and the sealing effect obtained by the high compression ratio, so that in the next moment of movement, when the spark plug jumps out of the spark, the mixture can complete the combustion action in an instant, and release the maximum burst energy to become the power output of the engine.

Conversely, if the combustion time is extended, the energy will be consumed and the temperature of the engine will be increased instead of participating in the power output of the engine, so we can know that the engine with a high compression ratio means that it can have a large power output.

Operating temperature. The operating temperature is deeply related to the change in the compression ratio. We all know the close relationship between the compression ratio and the combustion temperature, the compression ratio but the operation of the engine has a suitable and normal operating temperature range, the cooling system of the engine must help the whole engine to work in the appropriate temperature range, otherwise whether it is too high or too low the working temperature will make the engine unable to play the real efficiency, more, it may cause the cylinder and the piston to jam and unable to work, this fault is called the cylinder, so the requirements and role of the cooling system are self-evident. Generally speaking, the current working temperature of automobile engines is designed between 80-110, and the working efficiency of the engine can reach the ideal percentage of the original design under this appropriate and normal working temperature.

The compression ratio of modern diesel engines is generally between 12 and 22, but the compression ratio of ultra-supercharged diesel engines can be as low as 8. A few years ago, the compression of a gasoline engine was 6 10, but today it is generally between 9 12.

It depends on the ignition point of the fuel used. Usually gasoline only needs 500 degrees to ignite, while diesel needs 700 degrees to ignite, in order to reach the ignition temperature of diesel, so the compression ratio of diesel engine is high.

Although diesel and gasoline engines are both internal combustion engines, the characteristics of the fuels used vary greatly, resulting in significantly different operating methods and output characteristics. Diesel and gasoline are two completely different fuels, and the spontaneous ignition temperature of diesel is low, about 220, and the viscosity is large and not volatile; The autoignition temperature of gasoline is high, about 415 530, and the viscosity is small and volatile.

The compression ratio of a diesel engine is greater than that of a gasoline engine. The compression ratio of gasoline engines is basically limited to 9-11:1, while that of diesel engines can reach 17-24:1.

Although diesel has a low ignition point, it has a stable temperament, unlike gasoline, which is naturally unruly and difficult to control. Therefore, the diesel engine can be compression-ignition without worrying about the detonation of the engine.

But gasoline is the opposite. As a result, diesel engines have larger blocks, liners, and connecting rods than gasoline engines. Then compared with the engine of the same displacement, the diesel engine is naturally larger.

The role of the engine compression ratio:

Engine compression can increase the pressure, which can make the density of the gas larger, and the distance between molecules will be smaller, so that the fuel molecules and oxygen molecules will be closer together, and the combustion speed will be faster;

Temperature allows gas molecules to move faster, making it easier for fuel and oxygen molecules to interact with each other, which makes gas mixtures more likely to ignite. Moreover, the smaller combustion space can complete the combustion faster, and the faster combustion process also improves the performance.

The usual low compression ratio refers to a compression ratio of less than 10, and a compression ratio of more than 10 is considered a high compression ratio engine. The level of the compression ratio will directly affect the grade of gasoline used in the engine, generally speaking, the larger the compression ratio, the higher the gasoline grade required.

If gasoline is used below the recommended mark, problems such as "cylinder knocking", increased engine vibration, uneven driving, etc., can also impair engine performance and shorten service life.

In general, the compression ratio is 92 or 93 gasoline; 95 gasoline should be used for the compression ratio above.

In the compression stroke, the gasoline engine compresses the fuel mixture, which cannot be compressed too much, so as not to rise too high and spontaneous combustion occurs. Diesel engines compress air more and at a higher temperature, so it is more efficient.

The advantages and disadvantages of carbureted diesel generator sets are for your reference.

1: High thermal efficiency, low fuel consumption rate, some units have thermal efficiency as high as 45%, while fuel consumption rate is 190 grams per kWh, or even lower.

2: Low operating costs, the positive mold can use a variety of fuels, low requirements for fuel quality, suitable for heavy oil with high viscosity, and the ** of heavy oil is much lower than that of light diesel oil.

3: High reliability, stable power generation, usually the power generation is operated at 90% of the rated power.

4: The load adaptability is strong, and the fuel consumption rate changes little when the load of the unit changes from 50% to 100%, so the economy is good during peak regulation, and the load change range is large.

5: The unit starts quickly, and can quickly reach full power, the start of the diesel engine generally only takes a few seconds, in the emergency state can reach the full load within 60 seconds, in the normal state (900 seconds ---1800 seconds) to reach the full load.

6: The capacity of the single machine is small, and the operation technology is simple, which is easy for general operators to master. The maintenance is simple, the maintenance is convenient, the number of operators required is small, and the maintenance amount during the standby period is small.

7: For the generator set matched with high-supercharge, medium-speed diesel engine, its structure is compact (large power per unit volume).

8: Bootstrap rent moderation type, noise and vibration can be effectively controlled.

a. The gasoline engine only inhales a mixture of air and fuel in the suction stroke, so A is wrong;

B. At the end of the compression stroke, because the diesel engine compresses the fuel mixture to a greater extent, the disadvantage is higher, so B is wrong;

c. At the beginning of the stroke of finger failure, the diesel engine is burned by spraying mist diesel from the fuel injector, so C is wrong;

d. The suction, compression, and exhaust strokes are all completed by the inertia of the flywheel, so d is correct;

Therefore, choose D

Wrong! Compression ratio.

It refers to the ratio of the total volume of the cylinder to the volume of the combustion chamber.

i.e. (cylinder working volume + combustion chamber volume) combustion chamber volume.

Supplement: 1) Combustion chamber volume: When the piston is at the top dead center, the volume between the piston top and the cylinder head is called the combustion chamber volume. Represented by VC.

2) Total cylinder volume: When the piston is at the bottom dead center, the volume of the space above the piston top is called the total cylinder volume. It is denoted by va.

3) Cylinder working volume: The volume of space swept by the piston when the piston moves from the top dead center to the bottom dead center or has the bottom dead center to move to the top dead center, which is called the cylinder working volume. Expressed by VH.

4) Compression ratio: the ratio of the total volume of the cylinder to the volume of the combustion chamber, which is called the compression ratio. i.e. =v a v c

The ratio of the total volume to the volume of the combustion chamber (compression chamber volume), that is, (working volume + combustion chamber volume) combustion chamber volume.

No, it should be the ratio of the total volume to the combustion chamber volume (compression chamber volume), that is, (working volume + combustion chamber volume) combustion chamber volume.

1200～1400 kpa

The working condition of the engine depends on the cylinder pressure of the engine. Most EFI engines have cylinder pressures of 1200 to 1400 kpa, and a few high compression ratio engines have cylinder pressures above 1700 kpa.

The original design cylinder pressure of the engine mainly depends on the volume of the combustion chamber and the compression ratio of the engine, as well as whether there is a pressurization mechanism; In actual use, the main factors affecting the pressure of each cylinder of the engine are the amount of carbon deposited in the combustion chamber, and the sealing condition of the combustion chamber and whether the exhaust is smooth.

The formula for calculating cylinder pressure: the cylinder pressure of each cylinder is added and divided by the number of cylinders to be the average cylinder pressure. The average cylinder pressure of the engine must not be lower than 75% of the standard, otherwise it needs to be repaired.

Hello, gasoline engine ignition, diesel engine is compression ignition, so diesel engine compression ratio is larger, I hope it can help you.

The compression ratio indicates the degree to which the gas is compressed in the cylinder and also indicates the multiple of the volume change as the gas expands.

Diesel engine belongs to the compression-ignition engine, the compression stroke is close to the end of the diesel injected into the cylinder is by absorbing the heat of the high-temperature and high-pressure air that has been compressed in the cylinder and ignites by itself, in order to create favorable conditions for the spontaneous combustion of the diesel engine, the compression ratio must be designed higher, generally 16 22 is more suitable.

When the compression ratio is too high, due to the high temperature and pressure in the cylinder during the compression process, premature combustion or deflagration of the cylinder mixture will occur. Therefore, the compression ratio of the gasoline engine should not be too high, generally 6 9

Generally speaking, diesel engines have a large compression ratio. The compression ratio of diesel engines is generally 15-22, and the compression ratio of gasoline engines is generally 6-10. This is related to the characteristics of gasoline and diesel, diesel has a high viscosity and is not easy to evaporate, and the combustible mixture is ignited by compression ignition, which is suitable for low-speed engines, but the output torque is large and the compression ratio is large.