What is a gasoline car four stroke engine?

Air intake, compression, work, exhaust, crankshaft rotation two times The piston is called a four-stroke engine.

What is a four-stroke engine for gasoline vehicles.

Each working cycle of the engine is composed of intake stroke, compression stroke, power stroke and exhaust stroke, while the four-stroke engine needs to complete a working cycle, and the piston needs to make 4 strokes in the cylinder (that is, the crankshaft rotates 2 revolutions). Four-stroke engines are further divided into four-stroke gasoline engines and four-stroke diesel engines, and the main difference between the two is the different ignition methods. The gasoline engine is spark plug ignition, while the diesel engine is compression ignition.

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1. InhaleThe intake valve opens, the exhaust valve closes, and the piston moves downward from the top dead center.

2. CompressionThe intake and exhaust valves are closed, and the piston moves upwards from the bottom dead center.

3. Do workThe intake and exhaust valves are closed, and the piston moves downward from the top dead center.

4. Exhaust,The intake valve closes, the exhaust valve opens, and the piston moves upwards from the bottom dead center.

Classification of four-stroke engines.

Four-stroke engines belong to reciprocating piston internal combustion engines, which are divided into three categories: gasoline engines, diesel engines and gaseous fuel engines according to the different types of fuels used. A piston internal combustion engine fueled by gasoline or diesel is called a gasoline engine or a diesel engine, respectively. Piston internal combustion engines that run on natural gas, liquefied petroleum gas, and other gaseous fuels are called gaseous fuel engines.

Gasoline and diesel are both petroleum products that are the traditional fuels for automobile engines. Non-petroleum fuels are referred to as alternative fuels. Engines that burn alternative fuels are called alternative fuel engines, such as ethanol engines, hydrogen engines, methanol engines, etc.

l) Intake stroke.

The piston moves from the top dead center to the bottom dead center, the intake valve is opened, the exhaust valve is closed, with the piston moving downward, the cylinder volume above the piston increases, so the pressure is reduced to below the atmospheric pressure, that is, the vacuum degree is generated in the cylinder, under the action of external atmospheric pressure, the combustible gas is sucked into the cylinder by the intake pipe and the intake valve, as shown in Figure 3-l(a). When the piston reaches the top dead center, the intake air is finished, and the gas pressure in the cylinder is lower than the atmospheric pressure, and the temperature is about 80-l30.

a-intake stroke; b-Compression stroke; c-Work stroke; d-Exhaust stroke.

2) Compress the stroke.

At the end of the intake process, the intake and exhaust valves are closed, the crankshaft continues to rotate, and the piston moves upwards from the bottom dead center to compress the combustible mixture, as shown in Figure 3-1(b). When the compression ends, the temperature and pressure of the mixture are related to the magnitude of the compression ratio, the larger the compression ratio, the higher the pressure and temperature at the end of compression. At the end of compression, the temperature of the mixture is about 350-450 °C, and the pressure.

3) Work itinerary.

At this time, the intake and exhaust valves are still closed, when the piston is close to the top dead center, the spark plug emits an electric spark, ignites the compressed mixture, and releases a large amount of heat when the mixed gas is burned, so that the pressure in the cylinder increases suddenly, the instantaneous maximum temperature can reach about 2000, and the maximum pressure reaches the top dead center under the impetus of high-pressure gas, and the piston moves to the dead center, so that the crankshaft rotates to do work, as shown in Figure 3-i(c).

4) Exhaust stroke.

The exhaust gases generated after the combustion of the combustible mixture must be discharged from the cylinder before the next intake stroke is possible. When the expansion is close to the end, the exhaust valve is opened early before the piston reaches the bottom dead center, and the exhaust gas is discharged by itself by the pressure of the exhaust gas, and after the piston reaches the bottom dead center, when the top dead center moves, the exhaust gas is forced to be discharged into the atmosphere, and the exhaust stroke ends after the piston reaches the top dead center. At this time, the temperature in the cylinder is about 600 900, the pressure is about l03 l19kpa, due to the existence of the combustion chamber and the influence of gas flow resistance, the exhaust gas in the cylinder can not be completely discharged.

The residual exhaust gas accounts for about 5% l5% of the fresh gas in the inlet cylinder.

At the beginning of the next cycle, the live wall descends, the exhaust valve closes, the intake valve opens, and the four-stroke cycle starts again, and in this way, the above process is always carried out continuously and again in the operation of the gasoline engine.

Air intake, compression, work, exhaust.

Air intake, compression, work, exhaust.

Four-stroke: The course of the engine's movement.

Generally speaking, the composition of a four-stroke engine consists of two major mechanisms and five major system mechanisms, one is the crank connecting rod mechanism and the other is the valve mechanism. In the case of the system, there is an ignition system, a starting system, a lubrication system, and a cooling system. There are also five systems of the fuel supply system.

The working principle of the stroke gasoline engine is simply four strokes: air intake, compression, exhaust and ignition. The working cycle of a four-stroke gasoline engine consists of 4 piston strokes, namely intake stroke, compression stroke, work stroke and exhaust stroke.

How a four-stroke gasoline engine works

The gasoline engine is to mix the air and gasoline into a good mixture in a certain proportion, which is sucked into the cylinder during the suction stroke, and the mixture is compressed and ignited to produce heat energy, and the gas of high temperature and high pressure acts on the top of the piston, pushing the piston to make a reciprocating linear motion, and outputs mechanical energy through the connecting rod and crankshaft flywheel mechanism.

A four-stroke gasoline engine completes a working cycle in the intake stroke, compression stroke, power stroke and exhaust stroke.

Generally speaking, the four-stroke starter is composed of two major mechanisms, five major system mechanisms, one is the crank connecting rod mechanism, and the other is the Qiqiao gas distribution mechanism. In the case of the system, there is an ignition system, a starting system, a lubrication system, and a cooling system. There are also five systems of fuel supply, which are empty.

The four-stroke gasoline engine is composed of the body, crank connecting rod mechanism, valve mechanism, lubrication system, fuel system and ignition system (diesel engine does not have ignition system).

The working principle of the four-stroke gasoline engine is relatively simple, this engine has four strokes when running, and these four strokes are the suction stroke, the compression stroke, the power stroke, and the exhaust stroke. The intake valve opens during the suction stroke of the engine, at which point the piston runs downwards to draw in air or a combustible mixture. The intake and exhaust valves are closed during the compression stroke, at which point the piston runs upwards to compress the combustible mixture.

The spark plug ignites the combustible mixture during the power stroke, at which point the combustible mixture burns, and the burning combustible mixture pushes down the piston. During the exhaust stroke, the exhaust valve opens and the piston runs upwards to exhaust the exhaust gases from combustion. Four-stroke gasoline engines are naturally aspirated, turbocharged, and supercharged.

All three engines differ only in the way they intake air, and the four strokes all work on the same principle. In the actual use of the situation is more complicated, so most engines will also be equipped with variable valve lift system and variable valve timing system, which can change the operating state of the engine under different working conditions. The four-stroke diesel engine works on a similar principle as described above, except that the four-stroke diesel engine does not have a spark plug, and this engine is compression-ignition.

There are also two-stroke engines, but two-stroke engines are less common in ordinary civilian vehicles.

How a four-stroke gasoline engine works:

1. The working cycle of the four-stroke gasoline engine is composed of 4 piston strokes, namely intake stroke, compression stroke, power stroke and exhaust stroke;

2. The intake valve is opened, the exhaust valve is closed, the piston moves from the top dead center to the bottom dead center, and the cylinder volume above the piston increases;

3. The vacuum degree is generated, the pressure in the cylinder drops below the inlet pressure, and under the action of vacuum suction, the gasoline atomized through the carburetor or gasoline injection device is mixed with air to form a combustible mixture, which is sucked into the cylinder by the intake tract and the intake valve;

4. The intake process continues until the piston passes the bottom dead center and the intake valve is closed. Then the ascending piston begins to compress the gas.

Hello, the working principle of a four-stroke engine is mainly to utilize. Gasoline burns, then. The resulting force pushes the piston, which then moves back and forth to push the crankshaft to rotate and transmit the power to the spot.

Everyone knows the importance of the engine to the car, it is the power unit of the car, and at the same time, it is also the "heart" of the car, and it is an indispensable part of the car. Today we will talk about the specific operation process of the automobile engine, the gasoline engine generally has to go through the four processes of air intake, compression, combustion, slip leakage search, and exhaust to complete a cycle of work. That's why people call it also:

Four-stroke gasoline engine. So now let's talk about the specific steps to complete each stroke of a four-stroke gasoline engine.

Intake stroke: In this stroke, the intake valve is opened, the exhaust valve is closed, the cylinder communicates with the carburetor, the piston moves from the top dead center to the downward karma point, the volume above the piston increases, and a certain vacuum degree is generated in the cylinder. The combustible mixture is sucked into the cylinder.

When the piston reaches the bottom dead center, the crankshaft turns half a circle, the intake valve closes, and the intake stroke ends.

Compression source search stroke: After the intake stroke is completed, the intake valve and exhaust valve are closed at the same time. The crankshaft continues to rotate, the piston moves from the bottom dead center to the top dead center, the volume above the piston decreases, and the mixture entering the cylinder is gradually compressed, so that its temperature and pressure increase.

When the piston reaches the top dead center, the compression stroke ends.

Work stroke: Towards the end of the compression stroke, the spark plug emits an electric spark that ignites the combustible mixture. Due to the rapid combustion and expansion of the mixture, the pressure can reach 3 5 MPa in a very short time, and the maximum temperature is about 2200 2800 K.

The high-temperature, high-pressure gas pushes the piston down rapidly, and rotates the crankshaft through the connecting rod to work externally.

Exhaust stroke: After the mixture is burned, it becomes exhaust gas, in order to facilitate the next working cycle, these exhaust gases should be discharged from the cylinder in time, so at the end of the work stroke, the exhaust valve is opened, the piston moves upward, and the exhaust gas is discharged into the atmosphere. When the piston reaches the top dead center, the exhaust valve closes and the crankshaft turns to two weeks, completing a working cycle.

The four-stroke gasoline engine works like this: the core type of the four-stroke engine means that the working process is divided into four processes: air intake, compression, work and exhaust, and the four-stroke engine is to complete these four processes in the four strokes of the piston up and down movement.

When this kind of engine is running, Qisen will compress the gasoline through the pressure configuration inside the cylinder to achieve the effect of fuel **, which plays a role in the operation of the engine.

In the operation of a four-stroke gasoline engine, there are two major systems and five major mechanisms working together. This completes the power provided to the car.

Four-stroke concept.

Intake fuel injection. Compression evaporation.

Expansion does work. Exhaust gases.

Each step is a stroke, and the four steps are combined to achieve efficient combustion. The principle of intake fuel injection is to use the positive pressure of the head-on collision wind in the car and the negative pressure suction generated by the downward operation of the piston to suck in air; The ECU trip computer calculates the amount of fuel injected into the engine based on the amount of oxygen in the air, which is called the "air-fuel ratio", and mixes the oil and gas after inhaling the air and injecting the fuel, which lays the foundation for the second stroke.

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The compression stroke is a crucial step, as the piston moves upwards in the cylinder from bottom to top under the propulsion of the crankshaft. The purpose of this action is to compress a large volume of air into a small volume, and in the process of compression, the violent movement of molecules will produce high temperature due to friction - the purpose of compressed air is to heat up, and use the raised temperature to atomize the liquid fuel to evaporate into a gaseous state. It is important to know that the combustion rate of gaseous mixed oil and gas is much higher than that of liquid fuel oil, and the significance of increasing the speed is to fully combustion.

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Knowledge points: The concept of engine speed (rpm) is the speed of the crankshaft, which refers to how many revolutions are rotated in one minute, and the speed can also be understood as how many times work is done in a minute. Assuming that the engine runs at 2000rpm, then 2000 times of "intake and detonation" actions will be completed in one minute, and the time left for the expansion power stroke is the millisecond standard.

In order to fully burn and partially convert the mixed oil and gas into effective work (power) in such a short time, the premise is that the mixed oil and gas burn very quickly, which is where the compression stroke evaporates the fuel.

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Expansion stroke: Described in the vernacular as "ignition work" or "detonation push", a gasoline engine uses an electric arc from a spark plug to ignite a mixed oil gas, much like the concept of igniting fuel with a lighter. The diesel engine uses the ultra-high compression ratio to directly heat the air to a very high temperature, and uses the high temperature to make the diesel spontaneously ignite to achieve expansion work.

The so-called expansion refers to the process of violent movement of molecules in the chemical reaction during combustion, using the driving force of the movement to drive the piston to move from top to bottom, the piston drives the connecting rod and the connecting rod to promote the crankshaft to rotate, and the flywheel at the power output end of the crankshaft will output the rotating power (moment) to the gearbox, and drive the wheels to rotate through the transmission system.

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Exhaust stroke: The above three steps are completed in the cylinder of the engine, and the exhaust gas generated by combustion must be discharged from the cylinder to start the next round of "pressure and burst exhaust" of lead fiber, so exhaust is naturally an action that must be completed. So far, the four-stroke internal combustion engine has completed an energy conversion, and the four-step process of completing the four-step process is from low speed to high speed of the fuel-powered vehicle with 1000 6000 times per minute.