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Exhaust system - device and main malfunctions. Exhaust gas removal - a compromise between what is required and what is desired

car exhaust system- this is a structural group of spare parts, the work of which starts from the manifold, passes through the catalytic converter and ends with the muffler. The main task of this system is to remove exhaust gases from the engine, as well as sound waves that are generated as a result of the combustion process.

More about exhaust system functions

As we said above, exhaust system starts with the structural collector. It is attached directly to the engine outlet. Particularly high temperatures and gas pressure prevail in this place. The sealing gasket located in this place is subject to the greatest load. Therefore, in most cases, it is made from a non-combustible graphite composition, and is partially framed with copper rings, which allows it to fit snugly against the engine outlet. As a rule, exhaust gases from each cylinder are collected in this manifold. For this, a Y-hose is used. There is also a lambda probe, which is responsible for the distribution of the catalyst. A catalytic converter is connected to the Y-hose, or directly to the manifold. In order to mitigate vibrations from engine operation, the connection is made by means of a flexible metal hose or spring-loaded bolted connection. The catalytic converter is the most important component of the exhaust system. Directly in it, with the help of a porous ceramic block coated with precious metals, exhaust gases are cleaned. In the case of diesel engines, a particulate filter is used instead of a catalytic converter.

How does a silencer work, and why put two silencers instead of one?

The end of the exhaust system is a muffler. It is divided into several chambers, which are isolated from each other. The separate chamber technique divides the exhaust gases into several partial streams, thereby reducing the sound waves of each of the streams. This principle of operation is called the interference effect. As a result, a back pressure is formed in the muffler, which has direct influence for engine operation. Therefore, it is not recommended to open or remove insulating materials.

The muffler itself is filled with soundproofing basalt wool or metal shavings. Previously, asbestos wool was also used as a filler, but today this material is no longer used.

Today, large exhaust systems use an additional muffler. This is done allegedly because for powerful cars one muffler is not enough to absorb its “growl”. This is not entirely true. The use of an additional muffler is not necessary, since catalytic converters in modern cars also absorb sound, but the fad causes car companies to install a second muffler, which makes the car look more “driven”.

The individual components of the exhaust system are interconnected by pipes. A large number of connection points has led to the fact that now the exhaust system is produced in one block. Negative moment This approach is the fact that if one of the components fails, it is necessary to change the entire system, but thanks to modern high-quality wear-resistant materials, exhaust systems are extremely durable, and you should try hard to break something there.

An integral element of any car is the exhaust system, which performs a number of important functions, the main ones being the removal of exhaust gases and reducing the noise level at the time of the release of these gases into the atmosphere. Every responsible motorist, at least in in general terms must know how the exhaust system works in order to be able to immediately notice its malfunctions if they occur.

The exhaust system of a car is nothing more than a collection of muffler elements that are connected to the exhaust manifold. Among the main functions of the exhaust system are the function of removing hot toxic gases, cleaning emissions, as well as reducing exhaust noise.

The operation of the exhaust system of a car is inextricably linked with the functioning of the gas distribution mechanism, more precisely, with the operation of the exhaust valves and manifold. Structurally, the exhaust system consists of such elements as a downpipe, a catalyst, a resonator, a silencer, sensors or the so-called lambda probe, connecting clamps. Sometimes a particulate filter is included in the exhaust system. Consider constituent elements car exhaust system details.

Downpipe

The structural element appears as a curved pipe that connects to the outlet of the turbocharger or to the exhaust manifold. The downpipe must be made of special metals with good fire resistance properties. Sometimes the downpipe is made of stainless steel. If the car engine is different increased power, the composition of the exhaust system of the car may include several exhaust pipes.

Resonator

The resonator is a kind of "bank" of the muffler, in which the initial separation of the exhaust gases takes place. Also, the resonator is designed to reduce the speed of the exhaust. This structural element is made of refractory metals.

Catalyst

The catalyst is a special device designed to clean exhaust gases. Directly inside the container is the so-called "catalyst body", which can be divided into two components - ceramic and metal catalysts. The ceramic catalyst is a three-way exhaust gas catalyst. It consists of a stainless steel wire mesh covering a kind of cushion made of special ceramic materials, as well as thermal insulation, which is a heat-resistant case that has double walls. The composition of the metal catalyst, structurally similar to the ceramic one, includes corrugated foil coated with platinum or palladium.

The Lambda probe

A special sensor, called a lambda probe, is a sensitive oxygen element. It is mounted on a threaded connection in such a way that it comes into close contact with the exhaust of the car.

Muffler

A silencer is a kind of metal container with several internal partitions, the purpose of which is to reduce the level of noise that is generated at the time the exhaust gases are released into the atmosphere.

How a car exhaust system works

When the exhaust valve opens, gases are sent straight to the exhaust manifold. If the car is equipped with a gasoline engine, then the gases continue to move along the exhaust pipe. If the engine is diesel, then the gases exit into the exhaust pipe only after the turbocharger impeller is activated. At the next stage, the exhaust is sent to the catalyst, where harmful toxic impurities settle on the surface of the active element. It should be noted that the operation of the catalyst is possible only when elevated temperatures(from 250 degrees).

Exhaust gas composition control is assigned to the lambda probe. Some exhaust systems are equipped with two sensors placed at the catalyst inlet and outlet. In such systems, the ratio of air and fuel in the mixture is reflected much more accurately. The sensors send a signal to the injection control system, which is responsible for regulating the supply of fuel or air to the cylinders.

After the exhaust gases pass through the catalyst, they are "quenched" in the resonator, eventually entering the muffler. The muffler is designed to abruptly change the direction of the exhaust, thereby reducing the noise level. After passing through the muffler, the exhaust gases are released into the atmosphere.

It is very important to pay attention to the fact that the efficiency of the car exhaust system largely depends on the diameter exhaust pipe, as well as the cleanliness of the muffler and catalyst. If at least one of these elements will give some failures, exhausts can accumulate in the cylinders. As a result, not only will the engine power be significantly reduced, but the entire fuel system may also fail.

The history of the creation of the exhaust system of the car

The muffler is one of the oldest parts in the design of an automobile engine. The system, which dampened the roar that accompanies the operation of the internal combustion engine, was used even on the earliest production cars. The design flaw of the first engines was their low power, therefore, in order to increase the maximum speed and save fuel, the exhaust system was organized so that the exhaust gases during movement were discharged directly into the atmosphere through a special valve installed before the muffler. The driver opened this valve, and clouds of black smoke escaped into the air with a terrible roar. It was written that when driving through the streets of cities, the valve must be closed, however, for one reason or another, this rule was periodically violated. This state of affairs, and the governments of several countries were forced to pass laws prohibiting motorists from breaking the silence. The current situation prompted manufacturers to improve the exhaust system.

The device of the car exhaust system and the principle of its operation

The exhaust system is often referred to as a muffler, but this is not entirely correct. Among the elements of the system, not only, but also other devices. The exhaust system consists of several elements arranged in series. The first of them is the intake manifold, which is designed to remove exhaust gases from the engine cylinders and output them to a single intake pipe. Next comes the exhaust pipe, which connects the manifold and (if provided) and the middle part of the muffler (if there is no catalyst).

The phrase "Cook a spider" does not refer to the slang of witches and psychics. We are talking about artisanal production of equal length exhaust manifold

After the exhaust pipe, an optional catalyst is installed, which reduces the amount of harmful emissions in the exhaust gases. After the catalyst comes a resonator responsible for sound insulation. This is followed by the middle pipe, which ensures the movement of gases from the resonator to the muffler. And finally, a silencer, similar in function to the resonator, but having a different device. Depending on the design of the engine, exhaust gases, in addition to the listed elements, can pass through the pipes of the pressurization system and itself.

Exhaust System Operation Issues

Due to the fact that all components of the exhaust system are located in places where they are constantly in contact with an aggressive environment (active chemical elements in exhaust gases, salt and reagents on the road) and are exposed to high temperatures They are subject to increased wear and often require replacement.

A straight-through muffler is good for more than just waking up babies in strollers. This element, in combination with other modified parts of the exhaust system, is able to increase engine power.

The efficiency of the exhaust system largely depends on the diameter of the pipes connecting its elements, as well as on the condition of the muffler and catalyst. If the catalytic converter and muffler are clogged with soot, the ventilation of the cylinders will be inefficient, resulting in reduced power and the accumulation of combustion products on the internal surfaces cylinders. Among the main malfunctions characteristic of the exhaust system of a car are corrosion destruction, burnout of the walls of the exhaust gas system, and leakage. The poor condition of the catalyst affects the operation of the engine, since the modern one focuses on the readings of the temperature sensor built into the body of this element. The causes of an exhaust system malfunction can be different. This is a violation of the integrity of the elements of the system due to mechanical damage or loose connection of the main parts; operation of the car in adverse conditions (humid climate, abundant use of the reagent); problems in ; use of low-quality fuel and so on.

When buying a car older than 10 years, you need to be prepared to replace the entire exhaust system if the previous owner did not do it for you

In some cases, you can replace individual parts, and sometimes you have to change the entire system. In the process of spot repair damaged areas are usually cleaned, and the holes found are patched by welding.

Exhaust system tuning

Contrary to popular belief, exhaust system tuning is not just a means to annoy neighbors in the yard with a loud roar at night. Some elements of the exhaust system are easily visible from the outside. Often this circumstance, along with a real opportunity increase in power encourages owners to make modifications to the exhaust system.

When thinking about tuning the exhaust system, fire protection measures must be taken into account - simplified muffler elements emit a large number of heat

Modification of the exhaust system, if it is not done for the sake of "beauty", has two main goals. The first is a decrease in the so-called back pressure in the exhaust system, which allows to increase. To achieve this goal, it is necessary to modify the system from beginning to end. Back pressure is the resistance exerted by the walls of the duct to the flow of exhaust gases. To reduce it, the usual collector is changed to an equal length, that is, one in which the distance that the gas flows from each of the four cylinders pass along the way to the exhaust pipe is the same. In everyday life, these are called "spiders" for the characteristic appearance. In order not to create bottlenecks further along the gas flow, all connecting pipes, including the intake, are replaced with new ones of a larger diameter. In addition, the path is straightened as much as possible. The catalyst is thrown out of such a system, replacing it with a simplified one, and the final muffler is made as primitive as possible, direct-flow (that is, creating minimal resistance to gas flow). As a result of all these operations, the flow of gases gets the opportunity to pass the entire path almost unhindered. Unfortunately, the ability of the “muffler” to muffle something after modification practically disappears, and the system becomes very noisy. The second direction is heat removal from the engine compartment. The pipes of an equal-length collector, the most heated part, are covered with a special thermal spray with low thermal conductivity. This reduces the generation of heat in the engine compartment, which has a positive effect on the efficiency of the injection system.

Every car owner is familiar with the elementary design of a modern engine, and knows that the car has an exhaust system (at least everyone has heard about the muffler). But the most interesting thing is that few people are familiar with the principles of operation and design of the entire exhaust system, and can talk about all the processes that go through it. But everything changes dramatically when serious problems begin in it, and then it becomes clear that this system not so simple. In this article we will try to deal with the device, possible breakdowns and improvements.

How it all started

It is worth noting that the exhaust system of the car performs most of the work to normalize the operation of the engine, clean exhaust gases, reduce noise and exhaust gases. But the first systems really had the only function - to turn off the engine. internal combustion. The first engines were not distinguished by quiet operation and fuel economy, and all this at modest capacities, and the muffler could reduce the engine power by a few more points. Therefore, engineers had to go to tricks and find compromises between power and silence.

So, on the first cars with silencers, a bifurcated exhaust system with a mechanical valve was implemented. In the first mode, the exhaust gases passed through the muffler, which reduced the noise level. But the car could not start in this mode due to low power. Therefore, it was necessary to switch the valve to another position, which turned off the muffler, and sent the sound with the exhaust gases directly. This made it possible to increase power and easily start moving.

The only drawback of such a system was the city scorchers, who used the second mode in constant operation and "rushed" along the city streets. Because of this, the mayor's office of the cities received numerous complaints about excessive noise and danger on the streets. It was this that contributed to the emergence of a number of regulatory laws that regulated maximum level noise and traffic rules.

All bills contributed to the revision of the principles of the exhaust system. What led to the emergence modern species muffler, catalytic converter, etc. Helping reduce fuel consumption, reduce noise and keep emissions as low as possible harmful substances in atmosphere.

What does a modern exhaust system consist of?

After a short digression into history, we can move on to the theoretical structure of modern systems. It is worth noting that modern system consists of 5 fundamental blocks:

Receiving pipe;

catalytic converter;

Resonator;

Muffler;

Sensors.

It can already be understood that the whole system is not just a pipe with a silencer, but a complex mechanism for removing exhaust gases from an internal combustion engine, which we will consider in more detail.

Downpipe- this is the very beginning of the system, which provides a reliable connection to the exhaust manifold. Usually, this part of the system is made of heat-resistant steel with ceramic or other refractory gaskets. In order to ensure greater reliability during operation, this part is equipped with a strong but flexible corrugation. This eliminates the load from vibration, which is transmitted from the engine and body. If this part were absent, then the exhaust system would not withstand the load and burst in numerous places.

catalytic converter is a special filter for exhaust gases, which allows to reduce the level of influence of harmful substances on environment. The neutralizer contains special elements and substances that contribute to the oxidation and breakdown of harmful substances in exhaust gases. At the same time, most of the harmful compounds are converted into relatively safe carbon dioxide, nitrogen and water.

Resonator- this is a kind of brake for exhaust gases, which is an empty can. In which the flow is decelerated and oscillations are reduced. This results in an initial reduction in the noise level.

Muffler- This is the extreme detail of the exhaust system, which plays a major role in reducing noise. Inside is located complex structure from partitions and channels, the location of which is measured out according to complex calculations and contribute to a complete change in the flow of exhaust gases, and to reduce fluctuations. Therefore, modern cars are able to work almost silently.

Sensors- this is the main part of a modern car, helping to regulate the operation of the engine. Lambda probes (oxygen sensors) are installed in the exhaust system to help regulate the proportions and amount of the fuel mixture in the combustion chambers. Thanks to them, the electronic control unit is able to select the most efficient proportions of fuel and air, which allows you to achieve maximum power at any given time and reduce fuel consumption.

Practical use of the exhaust system

Despite the fact that the exhaust system is one of the most durable components of the car, and here are the reasons for high costs during repair.

The fact is that sooner or later, there will come a time when the catalytic converter (in most cases) or the muffler will be clogged with soot so much that the reduced capacity will affect the power and stability of the engine. Therefore, it will be necessary to change without fail, catalyst. The cost of which can vary from 10,000 to 200,000 rubles, depending on the model of the car.

But the main cause of failure is always corrosion, which inevitably forms on pipes, welds and all elements. It so happened that the exhaust system is always located under the bottom of the car, which allows water, dirt and aggressive chemicals from the road. In addition, the process of corrosion formation is aggravated by temperature changes (especially in the cold season). Therefore, if the muffler does not rust, it will burn out over time.

But these are the cases that will inevitably occur when long-term operation vehicle. In addition to them, you can speed up the processes using low-quality fuel, or damaging the exhaust system during careless driving, hitting the bottom of a curb or bump.

Also, one should visual inspection systems for proper fastening, or fastening condition. Remember that the exhaust system must not be allowed to come into contact with the car body or other elements. This can lead to unplanned repairs and high costs later. In addition to the exhaust system itself, the fastening of other elements may be broken, which will lead to contact with the exhaust system. For example: the most common case is the parking brake cable, which can come into contact with pipes and break after a while.

Naturally, all automakers recommend making repairs by completely replacing a worn out part. But there are many professional firms that deal with quality repair or tuning the exhaust system. For example: one of these firms is located in St. Petersburg, more full information can be obtained from this link - Silencer Master.

Exhaust system modification or tuning

It should be understood that the efficiency of the exhaust system depends on the diameter of the pipe and throughput. Any tuning can be divided into two types - a decrease in back pressure and a decrease in heat transfer in the engine compartment.

decline back pressure due to the increase in the diameter of the entire system. It should be understood here that replacing one element will not give a result. Also, you will have to dismantle the catalytic converter, replacing it with a flame arrester, which has a large throughput. Also, you will have to install an equal-length exhaust manifold (spider), which allows you to equalize the pressure of the exhaust gases in all cylinders and normalize air flow. In addition, it will be necessary to install a straight-through muffler. After that, the car will acquire additional power, but the volume of work will increase and the environmental performance of the car will decrease.

The second point will be a decrease in heat transfer from the exhaust manifold. This will help reduce the temperature of the engine and fuel system, which will provide a more accurate supply of the fuel mixture and improve engine cooling. For this, apply special means asbestos-based, not susceptible to high temperatures and providing good thermal insulation.

Conclusion

As it became clear from the above information, the exhaust system in a modern car plays a big role. Able to affect the power, volume and environmental friendliness of the vehicle.

One of the main systems of the car is the exhaust system, the work of which is aimed at releasing exhaust gases from the combustion chamber of the engine. It is noteworthy that in good condition, the exhaust system has minimal effect on engine operation. The system should not only remove exhaust gases outside the car, but also preliminarily reduce the level of their toxicity (environmental standards have not yet been canceled).

The modern exhaust system of a car, in addition to the above functions, is also a tuning element for both ordinary and sports cars, affecting not only their external parameters, but also their sound quality.

The exhaust system of a car looks like this:

collector, in which all exhaust gases are connected into a single stream;
catalyst, whose duties include reducing the level of toxicity of exhaust gases;
a downpipe, through which parts such as a manifold and a catalyst are connected;
resonator is responsible for noise reduction;
muffler, which, in fact, performs the same function as the resonator, but is made of a material with more high rates sound absorption;
the resonator and muffler are connected using the middle pipe.

The principle of operation of the exhaust gas removal system is represented by the following steps:

fuel mixture is injected into the engine cylinders;
as a result of its work, the combustion of the mixture occurs;
the result of combustion are toxic gases;
toxic gases under high pressure enter the collector;
in the collector, all toxic gases are combined into a single stream.

If the car is sports or tuned, then the role of the collector is performed by the so-called "spider", which owes its name to the presence of smooth bends (due to this, the resistance to gas flow will be the least). Having passed the collector or "spider", the gases, by means of movement through the exhaust pipe, enter the catalyst, from where they exit as harmless as possible.

In the same part of the exhaust system, the noise reduction process also takes place, as evidenced by the relatively pleasant sound familiar to motorists. After passing through the following stages of processing in the exhaust system, the gases leave the car by moving through the muffler.

It is noteworthy that, due to the creation of resistance to the flow of exhaust gases, automobile exhaust systems affect the operation of other components and assemblies of the car. By studying the instructions that came with the vehicle, you can clarify the level of back pressure, which is optimal. Remember that only the correct operation of the exhaust gas system allows you to operate vehicle in safe mode. There are more than enough cases when gases cease to be removed from the car, gradually penetrating into the car interior, therefore only a serviceable exhaust system of a car can guarantee the safety of vehicle operation.

Despite the fact that the production of the exhaust system for different brands cars are handled by various specialized companies, in most cases as consumable used stainless steel. A high-quality stainless steel exhaust system, subject to regular maintenance, can be used for the longest possible time.

When should I immediately address the issue of repairing the exhaust system? If a:

during the operation of the car, a loud roar is heard;
fuel consumption without visible reasons began to increase;
engine operation is no longer stable;
with enviable regularity, there is a loss of power level.

In most cases, these "symptoms" indicate that the exhaust system is out of order. Only professional repair using specialized equipment can guarantee the subsequent operation of the system and the entire vehicle. By entrusting repairs to professional specialists, you can be sure of the quality of the final result and highly qualified service.

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