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

Each car equipped with an internal combustion engine has at least a primitive exhaust system. It is installed not only to ensure comfort for the driver and others. This design plays an important role for efficient exhaust gas removal.

Consider the device of the exhaust system, as well as options for its modernization and repair.

What is a car exhaust system?

Under the exhaust system is meant a collection of pipes of different lengths and diameters, as well as volumetric containers, inside of which there are blocking elements. It is always installed under the car, and is connected to the exhaust manifold.

Due to the different design of the tanks (main silencer, resonator and catalyst), most of the sounds generated by the operation of the power unit are suppressed.

Purpose of car exhaust system

As the name of the system, it is designed to remove exhaust gases from the motor. In addition to this function, this design also serves for:

• Sound attenuation. When the engine is started, microexplosions of the air-fuel mixture occur in the working chambers of the cylinders. Even in small quantities, this process is accompanied by strong claps. The energy that is released is enough to drive the pistons inside the cylinders. Due to the presence of elements with different internal structures, the noise of the exhaust is suppressed on the partitions located in the muffler.
• Neutralization of toxic waste. This function is performed by a catalytic converter. This element is installed as close to the cylinder block as possible. During the combustion of the air-fuel mixture, toxic gases are formed that pollute the environment. When exhaust passes through the catalyst, a chemical reaction occurs, resulting in a reduction in the emission of harmful gases.
• The exhaust gas outside the vehicle. If you install a muffler immediately near the engine, then when the car is standing with the engine running (for example, at a traffic light or in a traffic jam), the exhaust gases would accumulate under the car. Since air is taken from the engine compartment to cool the passenger compartment, in this case less oxygen would enter the passenger compartment.
• Exhaust cooling. When fuel is burned in cylinders, the temperature rises to 2000 degrees. After the gases are removed through the collector, they are cooled, but even then they are so hot that they can injure a person. For this reason, all the parts of the exhaust system are made of metal (the material has a large heat transfer, that is, it quickly heats up and cools down). As a result, the exhaust gases do not burn those who pass the exhaust pipe.

Exhaust system device

Depending on the car model, the exhaust system will have its own design. However, basically the device system is almost the same. The design includes such elements:

• Exhaust manifold. This element is made of heat-resistant metal, since it takes on the main thermal load. For the same reason, it is imperative that the connection to the cylinder head and intake pipe is as tight as possible. In this case, the system will not allow the rapid flow of hot gases. Because of this, the joint would burn out faster, and details would need to be changed frequently.
• "Pants" or front pipe. This part is so called because the exhaust from all cylinders is connected in it into one pipe. Depending on the type of engine, the number of nozzles will depend on the number of cylinders of the unit.
• Resonator. This is the so-called "small" silencer. In its small tank, the first stage of slowing down the flow of exhaust gases occurs. It is also made of refractory alloy.
• Catalytic converter. This element is installed in all modern cars (if the engine is diesel, then a diesel particulate filter is used instead of the catalyst). Its task is to eliminate toxic substances from the exhaust gases generated after the combustion of diesel fuel or gasoline. There are several types of devices designed to neutralize harmful gases. The most common ceramic modifications. In them, the catalyst body has a cellular structure in the form of bee honeycombs. In such catalysts, the housing has a heater (so that the walls do not burn out), and a steel mesh is installed at the inlet. The surfaces of the mesh and ceramics are coated with the active substance, due to which a chemical reaction occurs. The metal version is almost identical to the ceramic one, only instead of ceramic its body consists of corrugated metal, which is covered with a thin layer of palladium or platinum.
• Lambda probe or oxygen sensor. It is placed after the catalyst. In modern cars, this part is an integral part that synchronizes the fuel and exhaust systems. When in contact with exhaust gases, it measures the amount of oxygen and sends a corresponding signal to the control unit (more about its device and principle of operation is described here).
• The main silencer. There are many different types of silencers. Each of them has its own design features. Basically, the "bank" has several partitions, thanks to which the loud exhaust is extinguished. Some models have a special device, which with the help of a special sound allows you to emphasize engine power (an example of this is the Subaru Impreza exhaust system).

At the junction of all parts, maximum tightness must be ensured, otherwise the car will make noise, and the edges of the pipes will burn faster. Sealers are made of refractory materials. Bolts are used for reliable fixation, and so that vibrations from the motor are not transmitted to the body, pipes and silencers are suspended from the bottom with rubber earrings.

The principle of the exhaust system

When the valve opens at the exhaust stroke, the exhaust gases are removed to the exhaust manifold. Then they go to the front pipe and are connected to the flow coming from other cylinders.

If the internal combustion engine is equipped with a turbine (for example, in diesel engines or turbocharged gasoline versions), then the exhaust from the manifold is first fed to the compressor impeller, and only then goes to the exhaust pipe.

The next point is the catalyst in which the neutralization of harmful substances occurs. This part is always installed as close to the motor as possible because a chemical reaction occurs at high temperatures (more about the operation of the catalytic converter in a separate article).

Next, the exhaust passes through the resonator (the name indicates the function of this part - to resonate most sounds) and enters the main muffler. In the cavity of the silencer there are several partitions with openings displaced relative to each other. Thanks to this, the flow is redirected many times, the noise is suppressed, and the most smooth and quiet exhaust comes from the exhaust pipe.

Possible malfunctions, methods for their elimination and tuning options

The most common exhaust system malfunction is burnout. Most often this happens at the junction due to a leak. Depending on the degree of damage, your own funds will be required. Burnout often occurs inside the muffler.

In any case, the diagnosis of the exhaust system is one of the easiest tasks. The main thing is to listen to the motor. When the exhaust noise begins to amplify (at first it acquires the original “bass” sound, like a powerful car), then it is time to look under the car and see where the leak occurs.

Muffler Repair Depends on the degree of wear. If the part is relatively inexpensive, it would be better to replace it with a new one. More expensive modifications can be patched with gas sludge and electric welding. There are many different opinions on this matter, so the motorist must determine for himself which method of troubleshooting to use.

If there is an oxygen sensor in the exhaust system, then its malfunction will make serious adjustments to the fuel system and may spoil the catalyst. For this reason, some experts recommend that you always have one operational sensor in stock. If, after replacing a part on the dashboard, the engine error signal disappears, then the problem was in it.

Exhaust system tuning

The exhaust system has a direct effect on engine power. For this reason, some drivers upgrade it by adding or removing some elements. The most common tuning option is the installation of a once-through muffler. In this case, the cavity is removed from the system for a greater effect.

It is worth noting that interference with the system circuitry can seriously affect the efficiency of the power unit. Each silencer modification is selected based on engine power. For this, complex engineering calculations are made. For this reason, in some cases, upgrading the system is not only unpleasant to the sound, but also “steals” the precious horsepower of the motor.

If there is not enough knowledge regarding the operation of the engine and the exhaust system, it is better for the motorist to seek help from specialists. They will help not only to choose a suitable element that creates the desired effect, but also prevent engine damage due to improper operation of the system.

Questions and answers:

What is the difference between an exhaust pipe and a muffler? The muffler in the exhaust system is a hollow tank with several baffles inside. The exhaust pipe is a metal pipe that extends from the main muffler.

What is the correct name for the exhaust pipe? This is the correct name for this part of the vehicle exhaust system. It is incorrect to call it a muffler, because the pipe simply diverts the exhaust gases away from the muffler.

How does the exhaust system work? Exhaust gases leave the cylinders through the exhaust valves. Then they go into the exhaust manifold - into the resonator (in modern cars there is still a catalyst in front of it) - into the main muffler and into the exhaust pipe.

What is the exhaust of the car? It is a system that cleans, cools, and reduces pulsation and noise from exhaust gases leaving the engine. This system may differ in different car models.