Silencer is an important part of the vehicle’s exhaust system . Its mission is to suppress noise from the working exhaust system .
Silencer reduces pressure and temperature exiting the combustor gases , reducing the concentration of harmful substances in the exhaust. With this spare fuel consumption is reduced , and the power of the car increases.
Operation of vehicle without a muffler causes damage to other parts of the exhaust system , because the combustion products have a temperature of 900 degrees, and contain harmful toxins . Filtering allows exhaust car parts to serve much longer, and the air to be cleaner.
The cause of failure of the muffler is usually burn-out and corrosion.
The breakdown of the muffler can be identified by increased noise and roaring sounds. The presence smell of exhaust fumes in the cabin is not only a sign that the muffler needs to be repaired , it is also a risk of suffocation by carbon monoxide .
If you carefully examine the condition of the parts under the hood and exhaust under the car , it is possible to detect particles of soot on them – this is also the reason for the visit to the body shop and repair the muffler.
The most drastic and inexpensive way to repair a welding . Indications are great for welding or damaged muffler impressive size of the resulting corrosion. Because minor injuries are often not noticed by the driver, and repairs fall silencers with large cracks or holes. Reliability and long service life of exhaust repaired by welding , make this method the most popular among motorists.
During repair work, it is important to carefully remove the muffler. In the operation, some parts may become attached to each other, and unskilled dismantling can only do harm .
If the muffler is damaged beyond repair , needs to be replaced.
What is a silencer?
Silencer is a back exhaust system, designed for removal of gases outside the vehicle and reduce exhaust noise. In this system traditionally consists of a resonator, and one, two or more main exhaust silencer according to the design of the exhausts.
Repair of silencer
The main part of the exhaust system!
From all parts of the exhaust system of a car, the muffler have to be repaired more frequently than others , because is assigned to it by the main features: sound absorption, reducing the speed of the exhaust gases and smoothing fluctuations .
The rear part of the exhaust system assumes the greatest load of waste gases in the most unfavorable environment ( snow , salt and chemicals on the roads) , so it is more often at risk of failure than the other elements of the exhaust system .
We do repairs, exhaust repairs of any structures , using material from leading European manufacturers and offer a choice of universal mufflers of different types and sizes.
Replacement of the catalyst
The value of the catalyst is not less important than the work of the muffler. Catalyst in the exhaust system plays the role of exhaust gas purifier , small cells are placed there in order to convert the harmful evaporation of fuel into less harmful compounds . And its function of sound absorption and a strong decrease of the load on the following him to the exhaust system can not be overvalued. Many drivers must have felt a great noise from muffler , driving in their car after clearing the interior of the catalyst , or after replacing it with a pipe. Further work in modern cars throughout silencing system and means including a catalyst directly influences the engine . The car equipped with a laid catalyst operates quietly and gently nearly inaudible , but its life is highly dependent on the correct operation of the engine ( its supply system and fuel metering , ignition system, the level of wear of the engine). If you still have the desire to remove the catalyst , it is necessary to install a resonator instead of it as in cars where no catalyst is provided by the manufacturer , but it can be necessary corresponding readjustment of electronics , ignition and injection .
Resonator exhaust system
The structure of the catalyst
What is in the catalyst?
There are two basic designs used in the catalysts for cars – the so called ” cell ” and ” ceramic beads .” The most common is cellular structure. The catalyst for cars has three elements :
1. Foil sound design in the form of porous material;
2 . Outer jacket , the purpose of which is to provide maximum surface area for catalytic materials – metals of the platinum group;
3 . The catalytic material (platinum , rhodium, palladium, etc. ),
so the original catalysts are quite expensive.
In modern cars 1 to 4 or even 5 catalysts can be installed. Of course, then the installation will cost a lot . Installation of universal catalyst is much cheaper .
Universal catalytic converters
Types of Catalysts : Which is better?
In today’s market for auto parts you can find two types of catalysts , metal and ceramic . Which one is better ? Let’s have a look!
Ceramic catalysts are more common, they are cheaper than metal . But they have a major drawback – fragility . The destruction of ceramics can occur for a variety of reasons : impact of debris or stone on the road , hit the water on a hot catalyst as a result of a car in a puddle of arrival , as well as a variety of problems ignition system.
The metal catalyst is more reliable and resistant to mechanical stress, but it is also more expensive.
However, both types of catalysts are not “tolerate” the following things:
1. Poor quality or leaded gasoline,
2. Antifreeze or oil entering into the combustion chamber,
3. Technical liquids of unknown origin, used for flushing the fuel system,
4. Running the engine at idle for too long
Diesel Particulate Filter
Particulate filter diesel engine complies with Euro 5 2.0 CDTI ECOTEC ® standard
System of the diesel particulate filter
To neutralize petrol engine exhaust gases catalytic converters are used. How can this problem can solved on diesels?
In a gasoline engine catalytic converter efficiently converts toxic compounds CO, CH , NOx into harmless components, CO2 , H2O and N2. When short-term deviations of the air-fuel mixture from the optimum ignition or violations can occur microparticles unburned carbon – in other words , the carbon black .
In a car with a serviceable converter black smoke does not happen. With diesel exhaust is not that simple ! When dealing with small loads of the gas temperature at the inlet to the converter is much lower than that of gasoline engines and soot has not enough time to burn . But throwing carcinogens into the atmosphere is a bad habit, that’s why a diesel engine must have a special converter , particulate filter. In modern engines, both nodes are placed in a single package that is located next to the engine .
Diagram of the exhaust system of diesel engine :
1 – engine control unit ;
2 – mass air flow sensor ;
3 – temperature sensor inlet gas to the turbocharger ;
4 – turbocharger ;
5 and 9 – gas temperature sensors before and after the particulate filter it;
6 – ratio sensor ( wideband oxygen sensor ) ;
7 – filter – converter ;
8 – Differential Pressure Sensor gases;
10 – the muffler .
Yet over time, filter is filled with soot . and you have to get rid of it. There are two methods :
1. engine management system does not interfere with the work process – so called assive regeneration It occurs at a temperature of gas at the inlet of the filter is not less than 350 degrees, in the presence of a catalyst – platinum deposited onto a ceramic honeycomb. Similar to the well -known modern cell converters , but there are important differences , as shown in Fig. 2 . The channels are divided into inlet and outlet . In the first , open on the motor side , with all gases coming bouquet toxic substances, including carbon black. The latter are open on the opposite side – of which gases are cleaned of soot move on to the neutralizer . Channels are arranged in a staggered and separated by thin walls filter impermeable to soot ( it remains in the inlet ), but transmissive gases . Their material – a porous silicon carbide coated with a mixture of alumina and cerium , and then , it is the supporting surface for the layer of platinum.
Organization Chart of channels of diesel particulate filter :
Soot accumulates in the inlet channel and the gases passing through the porous walls , go into the exhaust ports .
Necessary for afterburning of soot exhaust gas temperature to provide a diesel engine is not always possible – at low loads into the cylinders receive a lot of air and fuel is not enough! Enough heat is generated only in case of operation at relatively high power – for example, at a speed of 60-80 km / h , and even higher . But often this is not feasible , especially in the city, and the self-cleaning particulate filter is not happening. If you rely only on her, then over time the soot completely clog intake ports ( cell ) and workflow engine violated . To avoid this , you need to get rid of the soot , and this keep the heat inside the gas particulate filter .
The second way to clean the filter – an active regeneration . If necessary ( for this – below), the engine control unit begins to give a little extra fuel cylinders after the primary dose , just before the opening of the outlet valve. ” Excess ” diesel fuel work and no time off in the diesel particulate filter , where in the presence of platinum rapidly burns . The gas temperature increases and the soot burns virtually on command control unit.
Let us return to Fig. 1. The control unit 1, you have to decide when and for how long to include on an active filter regeneration . How? Very simply, by a pressure drop in the gas neutralizer . For this purpose, on both sides are integrated tube connected to the differential pressure sensor 8 . When the delta exceeds a predetermined value, regeneration activates. Normally it takes 10-15 minutes.
In fact , not all that easy. Differential pressure across DPF is connected with the exhaust gas volume flow , which in turn depends on the temperature. Therefore, before the particulate filter and thereafter installed and temperature sensors 5 and 9. And of course , for the completeness of the information control unit takes into account the mass air flow sensor 2 which is traditionally placed in the intake pipe .
Directly on the exhaust pipe of the engine there is sensor 3 . It monitors the temperature of the exhaust gas at the inlet of the turbocharger. If it is closer to the limit , beyond which could cause overheating and destruction of the very expensive unit , the control unit will limit the supply of fuel – and the temperature drops . Of course, the cleaning of the filter is most effective when it receives gas from the optimum air / fuel ratio . The control unit controls the composition of the mixture , based on the testimony of a broadband oxygen sensor ( ratio sensor ) 6, the tracking of oxygen content in the exhaust gases.
Ultimately, process all the information received , the control unit adjusts fuel supply to the engine cylinders. The status of all the components responsible for the cleaning of exhaust gases , on-board diagnostics system monitors . If correct, the light the Check Engine. For example, in a traffic jam due to the low temperature of the exhaust gases , in spite of all the efforts of the control unit , recovery will not start ! Soot filter becomes full – and in the instrument cluster lights up the signal with the image filter (if equipped design ) or flashing light ” check engine “. Then try to burn off the soot remains passive way – ride ten or fifteen minutes at a higher capacity. If after this warning light does not go out, have to go to the “chimney sweep” in the center.