A car is made up of many parts. Performance, dynamics, power, safety depend on the stable operation of each of them. The failure of one part can lead to serious consequences up to an accident.
Of course, every driver knows that the heart of the car is the engine. But his work would not be possible without a quality exhaust system. To understand its importance, let's draw a parallel with biology. You know that thanks to the lungs, the respiratory processes in the body are supported. They are also responsible for removing carbon dioxide from the blood. If this does not happen, then oxygen starvation begins.
Of course, a lack of oxygen in the blood cannot lead to anything good. In the worst case, brain function is disrupted, which, in turn, can lead to death. In the event of a malfunction of the exhaust system of a car, everything is not so tragic. But loss of power and increased fuel consumption are guaranteed. That is why it is important to understand how this unit works in order to carry out repairs if necessary.
Attention! In the worst case scenario, a malfunction of the car's exhaust system can lead to the ingress of exhaust gases into the passenger compartment.
An important function of the exhaust system of a car is to reduce engine noise. Also, one cannot ignore such important functions as improving the performance of internal combustion engines and cleaning exhaust gases before being released into the atmosphere.
History of creation
The first models of internal combustion engines created a deafening roar. In addition, they were very low-powered and allowed cars to reach extremely low speeds compared to modern supercars.
To slightly increase the power, the automakers of that time created the exhaust systems of a car in such a way that the exhaust gases entered the atmosphere immediately through a special valve. This device was a primitive analogue of a silencer, the installation of which had a positive effect on power and efficiency.
The driver himself had to open the valve of the exhaust system so that the exhaust gases would come out. At the same time, a deafening whistle was heard, frightening everyone around. This action was also accompanied black puffs of smoke.
Attention! The operation of the exhaust system valve was so terrible that drivers were forbidden to open it within cities.
Due to the too loud work of the exhaust system, there was some kind of confrontation between the townspeople and drivers. As a result, the governments of all countries have issued a law prohibiting the opening of the valve within the city.
Naturally, resourceful automakers could not miss such a chance to get ahead of their competitors. The development of a quieter exhaust system for cars began to gain momentum.
The first muffler prototype was created by automotive pioneers The Reeves Pulley Co. The author of the same invention is Milton Reeves. It happened in 1896. scientist created partition system, which was designed to minimize the noise generated by the internal combustion engine.
Of course, for more than 100 years, the muffler for the exhaust system of a car has gone through many upgrades. One of the main ones was carried out by the French engineer Eugene Goodry. It happened not so long ago. In 1962, the scientist filed a patent for a catalytic silencer. It is this design that is the basis for a modern device responsible for noise reduction.
The basic structure remained unchanged. All the same partitions greatly reduced the sound of the engine. But now additional materials have been used to create them, increasing the efficiency of the entire exhaust system. Moreover, all these elements were placed in closed systems.
Attention! Modern mufflers have a similar design, with one exception. Now most manufacturers use fiberglass as an absorbent material.
If we talk about the general structure of the exhaust system of a car, then over the past 50 years it has not changed much. Small improvements were made in the early 2000s, but they also concerned the muffler. Variable flow designs emerged. This made it possible to moderate the noise of the internal combustion engine for a different number of revolutions.
Also interesting innovations include electronic silencers. They serve to make the noise lower, using special headphones for this purpose. This modification allowed the design to take another small technological step into the future.
How does a car exhaust system work?
Device
To understand how the exhaust system of a car works, you need to take a closer look at its structure. The design itself is closely related to the functioning of the mechanism responsible for the distribution of gas. The mechanism itself consists of exhaust valves and a manifold.
The composition of the exhaust system of a car includes the following structural elements:
- intake pipe,
- resonator,
- catalyst,
- muffler,
- sensors or lambda probe.
Also, do not forget about the particulate filter, which makes the exhaust system for cars safer for the environment. This is the canonical scheme of the exhaust system of a car. Naturally, manufacturers can make additional elements and modifications to the design in order to achieve greater performance.
Attention! In detail, the main device of the exhaust system of a car, you can see in the diagram below.
The car exhaust pipe is a curved design with a welded sole. It connects to the exhaust manifold. In some modifications, a connection with a turbocharger can be observed.
The material of the exhaust pipe of the car exhaust system is fire-resistant metal. Although sometimes manufacturers can use stainless steel, such cases are quite rare. Cars with increased power have several pipes.
The resonator is shaped like a jar. It is in it that the exhaust gases are separated. Also, this element significantly reduces the speed of the exhaust. The material of manufacture is refractory steel.
The catalyst cleans the exhaust gases. In appearance, the device resembles a metal container. The inner layer is fireproof. The main structural element is the body. It, in turn, is divided into ceramic and metal.
The ceramic catalyst consists of three components that help neutralize the exhaust:
- The first element is a simple wire mesh. It is usually made from stainless steel.
- The mesh covers the ceramic cushion, which is also the second element. Its constituent elements are aluminum silicate and mica.
- Thermal insulation completes the design of the catalyst. In fact, this is a simple case, which is characterized by high heat resistance and has double walls.
The metal catalyst of the car exhaust system is coated with a layer of palladium or platinum. The basis is corrugated foil. In all other elements, the design is similar to the ceramic counterpart.
The lambda probe is mounted on a threaded connection. His the main task is to fix the amount of oxygen in the exhaust gases and transmit information to the control unit. On its basis, certain adjustments to the operation of the internal combustion engine are carried out.
The muffler is a simple metal container. Partitions and special materials are placed inside to help reduce noise during the operation of the car engine. The main task of the device is to moderate the flow of exhaust gases.
All elements of the design of the exhaust system of a car work with each other in close cooperation. The failure of one element leads to the fact that the entire system begins to fail. That is why car manufacturers spend a lot of time and money to create a truly reliable structure.
Principle of operation
The principle of operation of the exhaust system of a car is not particularly complicated. Moreover, it has not changed much since the introduction of this structural element into the car.
The exhaust system of the car still works thanks to the exhaust valve. When this mechanism opens, the exhaust gases enter the exhaust manifold. Then it all depends on the type of engine.
If the car has a gasoline engine, then the exhaust system sends gases through the exhaust pipe. In diesel engines, things are a little different. The exhaust gaseous substances cause the impeller to rotate. Naturally, this greatly increases the efficiency of the device.
Attention! In diesel internal combustion engines, exhaust gases enter the exhaust pipe only after the turbocharger impeller is forced to work.
From the exhaust pipe of the car, gaseous substances are redirected to the catalyst. There is a settling of harmful impurities. More precisely, active elements. The structural element itself is able to work normally only at temperatures of 250 degrees and above.
The lambda probe is responsible for the chemical composition of the gas. Ideally, the exhaust system of a car has two sensors at once. One is at the inlet to the catalyst, and the other is at the outlet. This allows you to ensure high productivity of the system.
The main advantage of systems with two sensors is a more accurate display of data. This structure allows you to more accurately fix the ratio of air and fuel.
After the lambda probe collects information, it sends it to the control unit. Based on the data received, commands are issued for the system responsible for injecting the fuel mixture into the engine cylinders. More precisely, there is an adjustment of the ratio of air and fuel.
As soon as the exhaust gases pass through the catalyst, the exhaust is “quenched”. As a result, the gaseous substance that enters the muffler poses a much lesser danger to the environment.
Attention! The mufflers change the direction of the exhaust. Because of this, the noise is drastically reduced.
After passing through all the elements of the car exhaust system, the exhaust gases escape into the atmosphere. In many ways, the efficiency of this unit depends on the thickness of the pipes, which also represent an important part of the mechanism. Moreover, the catalyst and muffler must be clean enough. Otherwise, the exhaust may be difficult.
If the catalyst and muffler are clogged, then the exhaust gases will accumulate in the car's cylinders. It is because of this that in most cases the power of the motor drops. In the most difficult cases, this leads to the fact that the entire fuel system becomes unusable.
Results
The exhaust system plays a huge role in the operation of the car. If it fails, there is a serious drop in power and increased fuel consumption. If timely measures are not taken, then this automotive unit may fail and cause damage to all other units.
Many motorists do not even realize how important the exhaust system of a car is in the trouble-free operation of the power unit, and do not pay due attention to its maintenance, as a result of which, engine failure may occur. It is for this reason that you should carefully familiarize yourself with the principle of operation of the exhaust system, its design features, and know what the exhaust system consists of.
In the operation of an internal combustion engine, an important role is played by the timely removal of exhaust gases to the outside, which begin to accumulate in the combustion chamber of the cylinder head immediately after the ignition of the fuel mixture. This task is designed to perform exhaust systems, or as motorists say, mufflers, which are equipped with all modern cars. The proper operation of the exhaust system, aimed at removing the remnants of the spent fuel mixture from the engine, depends entirely on the serviceability of all its constituent elements, which have some design differences depending on the type of engine.
The principle of operation of the exhaust system
The modern automobile exhaust system consists of several parts, unlike the first devices, which looked like a mechanical valve, which was forcibly opened by the driver of the car manually. All elements of the exhaust system, which are interconnected by means of fixing bolts through flanges located at their ends, are intended for:
- removal of exhaust gases and other unburned residues of the fuel mixture from the combustion chamber of the engine;
- reduce the noise emitted by the motor during operation;
- reducing the amount of toxic substances in the exhaust of the car;
- prevent toxic gases from entering the vehicle interior.
The device of the car exhaust system has a fairly simple principle of operation, which involves the removal of exhaust gases from the combustion chamber, passing them through pipes to the rear of the vehicle, while reducing noise generated by the motor due to the tightness of the entire structure and connections through flanges with heat-resistant seals.
Reducing the amount of toxic substances in exhaust gases is achieved through the use of catalytic converters (catalysts) in the design of the exhaust system, the performance of which is controlled by a special sensor called a lambda probe. In modern diesel cars, to improve the environmental friendliness of the exhaust, manufacturers use a particulate filter, which is also equipped with a diesel exhaust system.
In the design of a diesel engine, as well as a modern gasoline unit, a turbocharger is often used, which uses an air mixture of oxygen and exhaust gases taken from the exhaust manifold to supply the combustion chamber with an air mixture of oxygen and exhaust gases. The amount of exhaust gases entering the turbine is controlled by a sensor located on the exhaust manifold housing.
The structure of the structure and the purpose of its components
The parts that make up this design have different functional loads and their own designations, reflecting the stages of their work. The very scheme of the exhaust system and the names of its parts are as follows:
- exhaust pipe;
- catalyst or otherwise catalytic converter;
- resonator or flame arrester;
The exhaust manifold is a mounted type of equipment of the power unit, and is designed to receive exhaust particles and gases of the fuel mixture from the combustion chambers of each of the cylinders, and is made mainly of ceramics, cast iron or stainless steel alloys with increased thermal stability.
The downpipe, referred to by motorists as "pants", because of its similar appearance, is designed to combine several exhaust gas streams into one, and to move them further to the catalytic converter (catalyst). The pipe is often equipped with a so-called corrugation, with the help of which the vibration transmitted to the entire structure of the exhaust system by a running engine is damped.
The catalyst is a ceramic honeycomb, the surface of which is coated with a layer of an alloy of platinum and iridium, which allows exhaust gases to enter into a chemical reaction with them, as a result of which they are separated into oxygen and nitrogen oxide. The released oxygen in the catalyst helps to burn the remaining fuel mixture more efficiently, as a result of which only a nitrogen-dioxide-carbon mixture is supplied to the muffler. The operation of the catalytic converter is controlled by a special sensor lambda probe, transmitting a signal to the control unit of the vehicle's power unit. A similar sensor is also installed on the exhaust manifold to analyze the toxicity indicators of the exhaust gases entering the catalyst.
The resonator or flame arrester is designed to lower the high temperature of the exhaust gases, which is achieved using its cellular internal structure. The last detail in the design is the muffler, the task of which is to reduce the noise of a running engine due to a perforated pipe inside its body.
All components of the exhaust system are connected to each other through flanges using mounting bolts and heat-resistant seals, which are responsible for the tightness of this design, without which the full operation of the engine of a modern car is impossible.
Possible malfunctions, methods for their elimination and tuning options
The design of the exhaust system is an ideal option for tuning a passenger vehicle, due to the ease of installation of its components and the presence of a large assortment of various parts. The most common muffler tuning option is to install the so-called straight-through exhaust, when the resonator is removed from the system.
The most frequent malfunctions of the exhaust system are associated with the loss of tightness of parts or their connections, the seals in which can be very worn out. To replace the sealing elements, it is necessary to purchase an exhaust system repair kit, and after unscrewing the fixing bolts, change them to new ones.
The parts of the exhaust system made of various metal alloys are subjected to significant heating, a sharp temperature drop, and work under conditions of increased loads, as a result of which they are subject to severe wear and burnout of internal parts. The loud noise of the running engine and visual diagnostics of the exhaust system will allow to determine these breakdowns, after which the damaged structural part must either be replaced with a new one, in case of internal malfunctions, or its body must be repaired using electric / gas welding.
In modern cars, the operation of the power unit is controlled by the control unit, which receives certain signals from numerous sensors located on all its structural units. In the design of the exhaust system there is a sensor called a lambda probe, which measures the amount of toxic substances in the exhaust gases. Its malfunction or incorrect operation can only be detected by a diagnostic stand, after which the sensor must be replaced.
During the operation of any engine, fuel is burned and gases are released, which are products of its combustion. To remove exhaust gases from the engine outside the car body, a system of pipes and special containers is used, which as a whole make up the muffler.
Muffler is a very generic name for an exhaust system. The system consists of the following elements:
An exhaust manifold
Downpipe
Exhaust afterburner
Resonator
Muffler
Each of these elements has its own role, and in general they perform the work of neutralizing harmful emissions and damping exhaust noise.
Apparently, everyone has had to deal with a situation more than once in practice when one of the elements of the exhaust system burns out. It is impossible not to hear it, as the quiet sound of the engine’s operation abruptly changes to an unpleasant “growl”.
The more the muffler burns out, the louder the exhaust sound. If you remove the muffler altogether, then the sound of your engine can wake up all the inhabitants of the surrounding houses. This is due to the fact that the burnt gases under high pressure break out and create sound vibrations in the air of several hundred decibels.
The task of the muffler, in addition to reducing the sound of the exhaust, is not yet to create significant resistance to the exit of exhaust gases, otherwise this will affect the purge and filling of the cylinders, and therefore incomplete combustion and loss of power.
How are sound waves damped in a silencer?
The noise we hear is acoustic waves that carry energy. The task of the muffler is to convert the energy of air vibrations into thermal energy.
In order to carry out this transformation of energy, there are several types car muffler devices, which can be divided into four groups: limiters, resonators, reflectors and absorbers.
Limiters
One of the simplest vibration energy converters. In the silencer body, the inlet pipe narrows noticeably, creating acoustic resistance, and immediately after the narrowing, a large volume of the silencer body's capacity. Squeezing through the resistance at the narrowing of the pipe, the sound vibrations at the output are smoothed out by the volume. Energy begins to dissipate in the throttle, heating the gas. It turns out that the smaller the hole (choke), the greater the resistance, and therefore more effective smoothing. However, this creates serious flow resistance and as a silencer, it is not a suitable option. Although as a preliminary silencer - a very common design.
Resonators
Resonator-type mufflers use closed spaces located next to the pipe and connected to it by several rows of holes. Often in one building there are two compartments of different volume, separated by a blank bulkhead.
It turns out that each of the holes in the blind cavity is a resonator that excites natural frequency oscillations. The resonant frequency is abruptly damped due to a change in the conditions of its propagation due to the friction of the exhaust gas particles in the hole. Similar car muffler devices effectively dampen low frequencies and are used mainly as preliminary ones, standing first in the exhaust system. They do not resist the flow to a large extent, as they do not reduce the cross section.
Reflectors
Several pairs of acoustic mirrors are placed in the muffler housing, from which sound waves are reflected. If you make a kind of labyrinth of such mirrors, then in the end all the energy of sound vibrations will dissipate and the output will be only a barely audible sound.
A pistol silencer is arranged in a similar way. This is already a more advanced muffler design, although it creates a certain resistance to exhaust gases. It has mainly found application in standard systems as an end silencer.
Absorber
The principle of operation of such a silencer is based on the absorption of acoustic vibrations by some porous material. For example, by directing sound into mineral wool, it will cause its fibers to vibrate and rub against each other. Sound vibrations will be converted into heat.
The use of absorbers makes it possible to car muffler device without reducing the cross section of the pipeline, simply surrounding the pipe with holes drilled in it with a layer of absorber. The flow resistance in such a muffler will be minimal, but the noise reduction will also be minimal.
Therefore, in factory mufflers, mainly combined systems are used, achieving a significant reduction in noise with minimal flow resistance.
Even at the dawn of the appearance of the first cars in the late 19th and early 20th centuries, the muffler became the means that made it possible to popularize them among the urban population. The roar of the motor and in our time remains a significant problem when it comes to vehicles. Nowadays, new methods of noise suppression are used, which are generally quite effective. Over time, the silencer device has been constantly improved.
A modern car muffler is a unit designed to reduce noise levels, as well as temperature and exhaust emissions.
For any car, such parameters must comply with established standards. The difficulty lies in the fact that quite complex systems are needed to perform the tasks. Therefore, the silencer device includes several basic elements. Each of them performs a specific function.
Main elements of the system
The design of the muffler includes several elements. In fact, it will be approximately the same for each car model.
- Collector;
- Converter;
- Front muffler;
- Rear muffler.
The collector is connected directly to the engine itself, performing the task of removing gases. The load in this case is very high and this applies to both mechanical and thermal effects (up to 1000 degrees). Special requirements are imposed on the material from which this part of the car muffler is made. For this, the best alloys of cast iron and steel are used.
According to international standards, manufacturers must take care to reduce the harmful effects. And this task is assigned to the catalytic converter or converter. It is a special chamber where the actual cleaning of the gas mixture takes place.
Now manufacturers often produce catalysts capable of cleaning a wide range of harmful substances. To do this, the catalytic converter chamber is made multi-sectional. The body is made of metal or ceramic. At the same time, it has a cellular structure, due to which the area of contact of gases directly with the catalytic layer increases.
What materials are used for catalytic reactions
Directly the working area of the car muffler converter is covered with platinum and palladium. Upon contact with them, most of the harmful toxins in the exhaust gases are neutralized. The manufacturers themselves place the catalyst closer to the motor, since the high temperature speeds up the reactions.
Of course, there is still no universal muffler capable of neutralizing absolutely all toxins and harmful substances, but manufacturers are still constantly improving technology.
Front and rear mufflers
The last two parts are directly the mufflers of the car themselves in the sense that we are all used to. There are front and rear mufflers. Just they are intended directly to reduce the noise level, and they do not clean anything.
The front muffler is commonly referred to as the resonator. Gases, passing through the previous parts at high speed, create quite a lot of noise. Various gratings and numerous holes, firstly, reduce the speed of gas advance, and with it the vibration. Special materials are used to absorb sound effects. In this way, it is possible to remove the effect of resonance. It is here that the main work to reduce the noise level of the car takes place.
There are two main types:
- Active;
- Reactive.
Active silencers are made of sound-absorbing material and are relatively simple in design. The only problem is that over time it gets very dirty. In reactive chambers, combinations of expansion and resonator chambers are used.
The last part is actually the main muffler of the vehicle.
The function of the rear muffler is to finally absorb noise and exhaust gases. Its internal structure is heterogeneous and consists of a series of small chambers with special fillings.
It should be noted that in newer machines, as a rule, several technologies are combined at once. The porous structure, baffle system and various air ducts allow you to finally get rid of noise and reduce the temperature to a safe one.
Direct-flow muffler device
Those motorists who seek to increase the power of their vehicle in every possible way install special straight-through mufflers.
A feature of the direct-flow muffler device is that it is able to use the energy of the exhaust gases to increase the power of the car. This is not possible with a stock muffler.
The bottom line is that the exhaust gases exit the exhaust manifold with less resistance. Thanks to this, the engine spends a little less energy, since it needs to spend less energy to overcome pressure. And it is this difference that can be converted into useful driving power. 
The direct-flow muffler device includes a straight pipe with a perforated surface, actually enclosed in an outer casing. Inside contains fewer dividers and various chambers. Thus, the exhaust gases pass in a straight line without much resistance, but due to the perforated surface they expand freely, so that there are no special problems with the exit.
Noise absorption is provided by a special outer casing with applied absorbing composition. Thanks to him, the gases inside do not resonate, and the sound of the engine is within acceptable limits. To improve the effect, several separate outer segments can be used.
Quite often, different muffler systems are developed directly for specific car models, taking into account its features and performance.
The exhaust system of a car (exhaust system) is, as the name implies, an exhaust system. The exhaust system, contrary to popular belief, is a very important vehicle system. Its functions include:
- Reducing the toxicity of exhaust gases(positive effect on the environment)
- Noise suppression(reduces noise level)
- Discharge of hot, toxic gases behind the rear of the vehicle(prevents toxic gases from entering the cabin)
In addition, the exhaust system creates the necessary resistance to the exhaust gases, which affects the performance of the car. Also, exhaust systems, especially sports exhaust systems, play an important role in the appearance of the car, as well as in the sound, creating a pleasant timbre.
In the common people, the exhaust system is almost always simply called the "silencer". But this is not entirely true, since the muffler is just one of the components of the exhaust system. The exhaust gas removal system consists of: 
- collector(connects several exhaust outlets into one);
- downpipe(connects the collector to the catalyst or corrugation);
- corrugations(reduces vibrations transmitted from the engine)
- catalyst(converts toxic gases to harmless ones);
- resonator(reduces noise level);
- middle pipe(connects the resonator to the muffler);
- muffler(performs the same function as the resonator, but is arranged a little differently and uses a special fiber as a sound-absorbing material).
Consider the operation of the exhaust system in more detail. After the combustion of the fuel mixture, a lot of unburned toxic gases remain, under high pressure they enter the manifold, the task of which is to connect all the exhaust outlets into one. The collector usually creates a high resistance for the exhaust gases, therefore, very often, in tuning and sports, the regular collector is replaced by the so-called "spider". In fact, this is the same collector, but it has smoother bends to reduce the resistance to gas flow. After the collector, the gases enter the intake pipe, in which the temperature can reach 1000 ° C. From the intake pipe, the gases enter through the corrugation into the catalyst, the main task of which is to burn out unburned harmful compounds and convert toxic gases into harmless ones. In most vehicles, it also reduces noise levels and gives the exhaust a pleasant sound. After the catalyst, already relatively harmless gases enter the resonator, which significantly reduces the noise level, further along the middle pipe (which often has a strange, bizarre, tricky, twisted shape, since it must repeat the geometry of the bottom of the body and leave room for other vehicle units) gases fall into the muffler, which also reduces the noise level, like the resonator, but has a slightly different device.
Causes of failure of exhaust systems
Any car enthusiast can say that the exhaust system of a car is faulty and needs to be repaired, since a faulty exhaust system is accompanied by:
- loud "roar";
- engine power reduction(traction and acceleration deteriorate) ;
- unstable engine operation(rpm fluctuations at idle)
- the ingress of exhaust gases into the interior of the car;
- the appearance of soot on the details
Therefore, the repair of the exhaust system cannot be postponed, especially since repairing a "running" exhaust system will cost a much larger amount. The most common cause of exhaust system failure is corrosion and mechanical damage. Rust "eats" the bodies of mufflers, catalysts and resonators, as well as intermediate pipes and welds for fastening parts. As a rule, this happens due to constant, strong temperature changes, water, salt and reagents entering the exhaust system, accumulated condensate inside the muffler and resonator, as well as due to the active chemical compounds contained in the system.
