What is the principle of engine exhaust stroke work?

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. To solve this problem, the flywheel must have a large enough moment of inertia, which in turn leads to an increase in the mass and size of the entire engine. The use of multi-cylinder engines can compensate for the above shortcomings.

Modern cars mostly use four-, six- and eight-cylinder engines.

1) In the power stroke of the engine, the high-temperature and high-pressure gas pushes the piston to move downward, do work externally, and convert energy into energy at the same time.

2) There is a four-cylinder engine, the main technical indicators of which are shown in the table on the right. The displacement is equal to the sum of the working volume of the four cylinders, and the cylinder working volume refers to the volume swept by the piston from the top dead center to the bottom dead center, also known as the single-cylinder displacement, which depends on the area of the piston and the distance of the piston moving up and down (both the stroke is long). The rotational speed indicates the number of revolutions per minute that the crankshaft or flywheel has turned.

The engine does work in 1 s J and the displacement of a single cylinder v = l.

In each power stroke, the engine does work w = j.

3) In the work stroke, the work done by the gas on the piston can be expressed as w = p v, where p is the pressure of the gas on the piston, then p = pa. （1 l=10-3 m3）

4) Fig. 18 is a schematic diagram of the engine in the power stroke. The proof of the formula w = p v is given below, please complete the derivation process (each expression is required to be represented by s, l, or p):

Let the area of the piston be s, the stroke length is l, and the pressure of the gas to the piston is p, then the pressure of the gas to the piston is f= and the work done by the gas on the piston is w= , and according to the mathematical knowledge, the single-cylinder displacement of the engine v= , so w = p v.

The working principle of a two-stroke engine is that there are three holes in the engine cylinder block, namely the air intake, exhaust and ventilation holes, which are closed by the piston at a certain time.

First stroke: the piston from top dead center to bottom dead center. Complete two actions.

1. The spark plug is ignited, and the work is done - exhaust.

2. Close the air intake, press the air mixture from the lower part of the piston into the crankcase, and then enter the cylinder from the upper part of the piston.

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

1. Close all intake and exhaust air and compress the mixture.

2. To complete a work cycle, the piston needs to move two strokes, so it is called a two-stroke.

Advantage 1, two-stroke engines do not have valves, which greatly simplifies their structure and reduces their own weight.

2. The two-stroke engine is ignited once every rotation, while the four-stroke engine is ignited once every other rotation. This makes the two-stroke engine an important power base.

3. The two-stroke engine can run in any direction, which is important in some equipment such as chainsaws. A standard four-stroke engine can fail when the oil is shaking, unless it is upright. Solving this problem greatly increases the flexibility of the engine.

These advantages make two-stroke engines lighter, simpler, and cheaper to manufacture. The two-stroke engine also has the potential to pack twice as much power into the same space, as it has twice the power stroke per revolution. The combination of lightness and double power gives it an amazing "thrust-to-weight ratio" compared to many four-stroke engines.

There are three holes in the engine cylinder block, namely the air intake, exhaust and vent, which are closed by the piston at a certain moment. Its duty cycle consists of two strokes: Schematic diagram 1 of a two-stroke engine

The first stroke: the piston moves upwards from the bottom dead center, and after the three air holes are closed at the same time, the mixture entering the cylinder is compressed; When the air intake hole is exposed, the combustible mixture flows into the crankcase. 2.

Second stroke: When the piston is compressed near the top dead center, the spark plug ignites the combustible mixture, and the gas expands to push the piston down to work. At this time, the air intake hole is closed, and the combustible mixture sealed in the crankcase is compressed; When the piston approaches the bottom dead center, the exhaust hole is opened, and the exhaust gas is flushed out; Then the vent is opened, and the pre-pressurized combustible mixture punches the cylinder to expel the exhaust gas and carry out the ventilation process.

Intake and exhaust solenoid valve is broken symptoms if intake and exhaustCamshaftsIf the solenoid valve is broken, the engine fault light will be on, and the power of the engine will also be seriously reduced.

Most automobiles have engines that are designed with double overhead camshafts, which are mounted on the cylinder heads. The DOHC engine has two camshafts, one that controls the intake valve and the other that controls the exhaust valve. The camshaft and valve are both part of the engine's valve train, which is very important for the engine.

Most engines are designed with four valves per cylinder, with two intake valves and two exhaust valves. During the suction stroke, the intake valve opens and the exhaust valve closes, and during the compression stroke, the intake and exhaust valves close. During the power stroke, the intake and exhaust valves will close, and during the exhaust stroke, the intake valves will close, and the exhaust valves will open.

Some engines come with variable valve timing.

system and variable valve lift system, which can change the timing and lift of the valve according to different operating conditions, which can improve efficiency and reduce fuel consumption. Engines with variable valve timing have solenoid valves on the camshafts, and if this solenoid valve is broken, it will cause the engine to have a decrease in power. When the intake and exhaust camshaft solenoid valve of the engine is damaged, the riders should repair it immediately.

Generally four-strokes i.e. intake, compression, work, exhaust.

When intake, the intake valve is opened, the exhaust valve is closed, the compression and power stroke intake valve and exhaust valve are closed, the exhaust valve is opened when exhausting, and the intake valve is closed.

Suction is the movement of the piston from top to bottom, that is, from top dead center to bottom dead center, the piston moves from bottom to top when pressing the Ming Yu shrink, the piston does the power stroke from top to bottom, and the piston from bottom to top when exhausting.

The intake stroke is to let sufficient oxygen enter during combustion, to support combustion, no energy conversion, compression stroke is to compress air, increase temperature, mechanical energy into internal energy, combustion, power stroke is to convert the heat energy of gasoline combustion into mechanical energy, exhaust stroke is to eliminate exhaust gas, prepare for the next stroke, no energy to turn defeat and deification.

The order of work in a four-stroke engine is: intake, compression, work, and exhaust.

The answer is A

Four-stroke: The process of activating the motion of the cavity of the bureau.

The working principle of the four-stroke diesel engine is: the work of the diesel engine is completed by the four processes of air intake, compression, combustion expansion and exhaust, which constitute a working cycle. A diesel engine where the piston goes through four processes to complete a working cycle is called a four-stroke diesel engine.

Intake stroke: the intake valve is opened, the exhaust valve is closed, the piston is driven by the crankshaft and connecting rod, moves from the top dead center to the bottom dead center, sucks fresh air into the cylinder, the piston reaches the bottom dead center, and the intake stroke ends.

Compression stroke: the intake and exhaust valves are closed, the piston is driven by the crankshaft and connecting rod, moves from the bottom dead center to the top dead center, the air sucked into the cylinder is compressed into high temperature and high pressure gas, and when the piston reaches the top dead center, the compression stroke ends.

Power stroke: After the compression stroke is over, (the intake and exhaust valves are still closed) the fuel injector will inject fuel into the cylinder, under the action of high temperature and high pressure gas, the fuel is compression-ignited, and a huge amount of energy is generated in the cylinder, which pushes the piston to move from the top dead center to the bottom dead center, the crankshaft flywheel group stores and outputs energy, and when the piston reaches the bottom dead center, the power stroke ends.

Exhaust stroke: the intake valve is closed, the exhaust valve is opened, the piston is driven by the crankshaft and connecting rod, and moves from the bottom dead center to the top dead center, and the exhaust gas after combustion in the cylinder is discharged, and when the piston reaches the top dead center, the exhaust stroke ends. In the four strokes of air intake, compression, work and exhaust, only the power stroke produces energy, and the other three strokes are completed by the inertia of the crankshaft and flywheel.

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.

The differences are many.

The four-stroke engine crankshaft completes a work cycle every two weeks, and the piston up and down completes a work cycle every two times, and the two-stroke engine crankshaft rotates for one week, and the piston completes a work cycle up and down.

The four-stroke has an independent valve mechanism, which controls the opening and closing of the valve through the camshaft, timing chain or valve ejector rod, which is more precise, and the intake and exhaust system is perfect, so it is more fuel-efficient. Two-stroke engines use pistons to open and close the intake, exhaust and scavenging ports located on the cylinder block at different stages during the upward and downward movements, which can cause waste. Therefore, the four-stroke car with the same displacement is more fuel-efficient than the two-stroke, and the two-stroke car is more fuel-intensive and polluting because the oil is discharged without combustion.

Four-stroke engines are relatively large in size and weight due to their complex structure, and they are also expensive, while two-stroke engines are simple in structure and small in size, and they are cheaper.

The four-stroke engine relies on the inertia splash of the oil pump and the crankshaft to lubricate the whole engine, the oil in the two-stroke engine only lubricates the transmission mechanism, and the cylinder, piston and crankshaft rely on a separate oil tank to mix the oil into the gasoline and burn it together through the oil pump or manually, and at the same time achieve the purpose of lubricating the relevant parts, so the two-stroke engine will emit blue smoke, while the four-stroke engine will not smoke normally.

Under the same conditions, the two-stroke engine revs higher and the cylinder area heats more, so its heat sink is also larger. Two-stroke engines have more noise and vibration, and four-stroke engines have lower noise and vibration.

Four-stroke engines are more advanced and widely used in all kinds of fuel-powered machinery, while two-stroke engines are less and less used, and are only used for the power of small motor vehicles such as special track cars and some small general-purpose engines (such as chain saws, lawn mowers, etc.).

The working principle of a four-stroke diesel engine is the same as that of a gasoline engine, and each working cycle is also composed of an intake stroke, a compression stroke, a power stroke and an exhaust stroke. Because diesel has a low autoignition temperature and high viscosity compared with gasoline, it is not easy to evaporate, so the diesel engine uses compression ignition at the end of compression to ignite (compression ignition ignition), while the gasoline engine is ignited by a spark plug. Hope to adopt.

Its function is to remove exhaust gases.

According to the data of the Pacific Automobile Network, the function of the exhaust stroke is to remove the exhaust gas, and the mechanical energy is converted into kinetic energy. At the end of the working stroke, the exhaust valve opens. Due to the high pressure in the cylinder, the dust is cleared by atmospheric pressure, and the high-temperature exhaust gas is quickly discharged from the cylinder.

This stage is the free exhaust phase, where the hot exhaust gases are discharged through the exhaust valve at local sound speed.

When the piston arrives near the top dead center, the exhaust faction and the front process end, because the combustion chamber occupies a certain volume, it is impossible to completely exclude the exhaust gas at the end of the exhaust, and the remaining part of the exhaust gas is called the residual exhaust gas, the car belongs to the piston engine, and its working process is divided into four processes: intake stroke, compression punch orange stroke, power stroke and exhaust stroke, so the piston engine is also called four-stroke engine.