Briefly describe the working characteristics of gasoline engine air intake, compression, work and ex

1. Intake stroke.

The working fluid that enters the cylinder is pure air. Due to the less resistance of the diesel engine intake system, the pressure at the end of the intake air is pa= (, which is better than that of a gasoline engine.

High. The intake terminal temperature ta=300 340K, which is lower than that of a gasoline engine.

2. Compression stroke.

Since the compressed working fluid is pure air, the compression ratio of the diesel engine.

Higher than gasoline engines (generally =16 22). The pressure at the end of compression is 3 000 5 000 kPa, and the temperature at the end of compression is 750 1 000 K, which greatly exceeds the autoignition temperature of diesel (about 520 K).

3. Do power stroke.

When the compression stroke is nearing the end, under the action of the high-pressure oil pump, the diesel is sprayed into the cylinder combustion chamber through the injector at a high pressure of about 10MPa, and it is mixed with air in a very short time and immediately ignites and burns by itself. The pressure of the gas in the cylinder rises rapidly to a maximum of 5 000 9 000 kPa and a maximum temperature of 1 800 2 000 K. Because the diesel engine is self-ignited and burned by compression, the diesel engine is called a compression-ignition engine.

4. Exhaust stroke.

The exhaust of a diesel engine is basically the same as that of a gasoline engine, except that the exhaust temperature is lower than that of a gasoline engine. General TR = 700 900K. For single-cylinder engines, their rotational speed is uneven, the engine works unsmoothly, and the vibration is large.

This is because only one of the four strokes is work-done, and the other three are those that consume power in preparation for work.

The four-cylinder engine ignited the bai order, only 1243 or 1342, because the du14 was in the same position, and 23 in the same position.

The gasoline engine is a working cycle that includes four piston strokes (the so-called DAO piston stroke refers to the process of the distance between the piston from the top dead center to the bottom dead center): intake stroke, compression stroke, expansion stroke (power stroke) and exhaust stroke. The working process of a four-stroke gasoline engine is a complex process, which consists of four strokes (strokes) of air intake, compression, combustion expansion, and exhaust.

1. Air intake stroke:

The intake valve opens, the exhaust valve closes, the piston moves from top dead center to bottom dead center, and the cylinder volume above the piston increases, creating a vacuum.

The pressure in the cylinder drops below the inlet pressure, and under the action of vacuum suction, it passes through the carburetor.

or gasoline injected by an atomized gasoline, mixed with air to form a combustible mixture, which is sucked into the cylinder by the intake tract and intake valve.

2. Compression stroke:

The intake and exhaust valves are all closed, the combustible mixture in the cylinder is compressed, the temperature of the mixture rises, and the pressure rises. Before the piston approaches the top dead center, the pressure of the combustible mixture rises to about 0 6 1 2MPa, and the temperature can reach 330 430.

3. Work itinerary.

During this stroke, the intake and exhaust valves remain closed, and when the piston approaches the top dead center, the spark plug is installed in the cylinder block hall or cylinder head.

An electric spark is emitted to ignite the compressed combustible mixture, and when the combustible mixture is burned, a large amount of heat energy is released, and its pressure and temperature increase rapidly. The resulting high temperature, high-pressure gas pushes the piston from top dead center to bottom dead center, passing the connecting rod to the crankshaft.

Rotate and output mechanical energy.

4. Exhaust stroke:

The exhaust gases generated after the combustion of the combustible mixture must be removed from the cylinder for the next working cycle. When the expansion is nearing the end, the exhaust valve is opened, and the exhaust gas is discharged freely by the waste pressure, and when the piston reaches the top dead center and then moves to the top dead center, the exhaust gas is forced to be discharged into the atmosphere.

What are the components of an air jet engine with a compressor? and briefly describe the role of each part.

The role of the turbine engine 1, the air intake: the purpose of the orange is to make the air flow into the compressor at a smooth flow rate 2, compressor: through the rotation of the compressor impeller with blades, the pressure of the air increases, the density increases, so as to improve the efficiency of combustion, and at the same time increase the jet speed and increase the thrust.

3. Combustion chamber: Fuel and air are mixed and ignited in this space to do work and provide energy. 4. Turbine in the circle:

It is under the same control as the compressor, and can compress the air flow to drive the compressor to rotate. 5. Tail nozzle: At the tail of the engine, the flow rate of the airflow can be increased through a special structure, the thrust of the engine can be improved, and the thrust direction can be changed by noise reduction.

The principle of turbojet engine is actually the same as that of the common piston engine, which is the four functions of air intake, pressurization, combustion and exhaust, but the biggest difference with the piston engine is that all the functions in the system are operated simultaneously and continuously.

Summary. Pro, there are many kinds of modern car intake control applications, intake turbocharging; variable valve timing control; Intake noise control; Intake manifold control; Intake inertia pressurization control; Variable air intake system control; Cylinder breaking control and other auxiliary devices, etc. 1. Intake turbocharging - using the high temperature and high pressure exhaust gas discharged by the engine to drive the exhaust gas turbine to rotate, the exhaust gas turbine drives the compressor on the same shaft to rotate together, and the air compressor compresses the air filtered by the air filter, so that the air is compressed and pressurized into the engine cylinder, and a device that improves the air intake volume of the engine 2, the control of variable valve timing In order to improve the engine power performance, only improve the charging efficiency, control the gas distribution phase and can change with the different engine speeds, It is also possible to use the inertia and resonance effect of the intake air, which is the best way to improve the intake efficiency3. Intake Noise Control - The intake system of the engine is a very complex noise source, including various types of noise, and the mechanism of each noise generation is also different, which will have a certain impact on the intake efficiency.

In order to improve the intake efficiency, the main intake control system applied to gasoline engines is included.

Pro, there are many kinds of modern car intake control applications, intake turbocharging; variable valve timing control; Intake noise control; Intake manifold control; Intake inertia pressurization control; Variable air intake system control; 1. Intake turbocharging - the use of high temperature and high pressure exhaust gas discharged by the engine to drive the exhaust gas turbine to rotate, the exhaust gas turbine drives the compressed air belt machine on the same shaft to rotate together, and the air machine compresses the air filtered by the air filter, so that the air is compressed and pressurized into the engine cylinder, and the engine air intake volume is increased 2, variable valve timing control In order to improve the engine power performance, only to improve the charging efficiency, Controlling the valve phase and can change with the different engine speeds, and can also use the inertia and resonance effect of the intake air, which is the best way to improve the charging efficiency3. Intake Noise Control - The intake system of the engine is a very complex noise source, including various types of noise, and the mechanism of each noise generation is also different, which will have a certain impact on the intake efficiency.

4. Control of the intake branch pipe - use the intake fluctuation effect and minimize the difference between the intake speed of the engine at high and low speeds, so as to improve the economy and power of the engine. Zaozhi 5, Pei Hui intake inertia pressurization control bench Zhongmin - use the pressure generated by the intake inertia to provide the air intake rate 6, variable air intake system - each cylinder is equipped with two air intake channels, which are changed through the conversion valve, and when the engine is high speed and large load, the air intake path is reduced and the inflation volume is increased, so that the power performance of the engine is greatly improved.

Summary. Hello, now fashionable vehicle modification, there are changes to the appearance, there are changes to the suspension, there are changes to the power, but in the final analysis, the depth of a car modification potential, but also depends on the quality of the foundation. Let's talk about power, many people think that the air intake modification in the power is to add a mushroom head, thinking that the air intake efficiency can be improved.

In fact, this is very one-sided, and the most relevant thing to follow up the gas efficiency should be the shape of the intake pipe! The shape of the intake pipes of different shapes, lengths and cross-sections represents the design appeal of this engine. Here, let's talk about the shape of the intake pipe.

Under different working conditions of the engine, what characteristics of the intake pipe and filling pipe are better.

Hello, now fashionable vehicle modification, there are changes to the appearance, there are changes to the suspension, there are changes to the power, but in the final analysis, the depth of a car's modification potential, but also depends on the number of silver blocks. Let's talk about power, many people think that the air intake modification in the power is to add a mushroom head, thinking that the air intake efficiency can be improved. In fact, this is very one-sided, and the most relevant thing to follow up the gas efficiency should be the shape of the intake pipe!

The shape of the intake tubing with different shapes, lengths and cross-sections, represents the design appeal of this engine. Here, let's talk about the shape of the intake pipe.

In terms of shape, the air intake duct can be divided into a vertical air intake and a swing air intake. Because of the small intake resistance, the vertical air intake is conducive to the formation of resonance at high revs, improving the intake efficiency, and is also convenient for arranging fuel injectors. The gyratory air intake can be conducive to the generation of vortex during air intake, improve the mixing degree of air attack gas and gasoline, and improve the combustion efficiency in the cylinder at low rotation, which is generally suitable for the hypoenvy engine that emphasizes the performance of low rotation.

Here we will take two more extreme examples to explain to you. The V10 engine mounted on the M5 does not use a lot of complex technologies to improve the response speed of the engine, high power output at high speeds, and so on. Rather, it is the most direct and pure way to achieve the perfect interpretation of high performance.

The V10's 10 engine's 10 intake pipes are all very short vertical and have throttle valves in each of the bends, which are the most obvious design features that emphasize high revs and responsiveness.

The most obvious rotation of the intake duct is the diesel engine, the general speed of the diesel engine is not high, the emphasis is on the power performance at low speed, so the diesel engine is no exception to the Shenchang talk is all about the use of gyratory intake. Some diesel vehicles also deliberately increase the degree of rotation at the end of the intake tract in order to produce the maximum intake vortex and achieve the purpose of increasing the degree of air and fuel mixing.

Answer]: The valves are stacked.

Analysis: The ventilation process of an internal combustion engine is mainly divided into three stages.

1. Exhaust stage.

Free exhaust stage: In the crankshaft angle from the opening of the exhaust valve to the bottom dead center of the exhaust, the gas pressure in the cylinder is higher than the exhaust back pressure in the exhaust pipe, and the gas in the cylinder can be automatically discharged from the cylinder while working on the piston.

Forced exhaust phase: The exhaust from bottom dead center to top dead center. The effective power exhaust fluidity of the engine needs to be consumed: supercritical exhaust, subcritical exhaust.

2. Intake process: From the opening to closing of the intake valve, the whole process of inhaling fresh charge in the internal combustion engine allows the intake valve to be opened in advance before the suction top dead center, and should be postponed after the suction bottom dead center.

3. Valve stacking: Before and after the dead center of the intake and exhaust, due to the early opening of the intake valve and the delay of the exhaust valve, the internal combustion engine is opened at the same time during the period from the opening of the intake valve to the closing of the exhaust valve, which is called valve stacking.

Answer: The four strokes of the gasoline engine have their own characteristics and functions The characteristics of the suction stroke are that the intake valve is open, the exhaust valve is closed, and the piston moves downward, and the effect is to suck in the mixture of gasoline and air; The compression stroke is characterized by the closure of the intake and exhaust valves, and the upward movement of the piston, which compresses the mixture of fuel and air, so that their internal energy increases, the temperature rises, and the state ignition forms a high-temperature and high-pressure mixture; The characteristics of the power stroke are that the intake valve and exhaust valve are closed, the fuel and air are mixed with high temperature and high pressure and the virtual gas is burned, and the volume expansion pushes the piston to move downward, and the role is to do work externally; The exhaust stroke is characterized by the closing of the intake valve, the opening of the exhaust valve, and the upward movement of the piston, which is used to discharge the exhaust gas out of the cylinder In summary, option a is the role of the exhaust stroke; Therefore, option B is the role of the power stroke; So option c is the role of the inspiratory stroke; Option d is the effect of the compression stroke, so the correct answer is d

The first null: compression.

The second emptiness: doing work.

Key points: (1) A working cycle of an internal combustion engine includes four strokes: suction stroke, compression stroke, power stroke, and exhaust stroke (2) In each stroke, it is accompanied by energy conversion and loss Among them, it is important to master two strokes:

Compression stroke: converts mechanical energy into internal energy; Do the power stroke, which converts the internal energy into mechanical energy

In the four processes of suction, compression, work and exhaust, the gasoline engine converts mechanical energy into internal energy is the ( ) stroke, which will be internal.

In the four processes of suction, compression, work and exhaust, the gasoline engine converts mechanical energy into internal energy is the (compression) stroke, and the internal energy into mechanical energy is the (work) stroke.