About EGR: Whether you are gasoline diesel or turbo steamed duck, is it blocked?

EGR is the abbreviation of English Exhaust Gas Re-circulation, and the Chinese name is exhaust gas recirculation. The so-called EGR exhaust gas recirculation means that part of the exhaust gas discharged after engine combustion does work returns to the intake manifold and enters the cylinder again for combustion together with fresh mixed gas.

Because the exhaust gas contains a large amount of CO2, the oxygen concentration in the original mixture is diluted, and the combustion speed slows down, so that CO2 cannot be burned, thereby absorbing heat to reduce the maximum combustion temperature of the cylinder, reducing the emission of nitrogen oxides to reduce pollution and promoting environmental protection.

The working state of EGR varies according to the fuel type and power zone, but it can be roughly divided into cold car state, low load, high load and other States, and there will be differences in working conditions due to temperature difference. The details can be confirmed according to your own model and model.

Functions, advantages and disadvantages of EGR

On the positive side, the function of EGR is based on environmental protection, because there was no EGR before the national standard (or similar European standard and American standard), so its fundamental reason is environmental protection, which is the first point;

Secondly, it can reduce the combustion temperature and suppress knocking, which is an auxiliary function, because there are many ways to do these two things, not just EGR, which we must be clear about.

So in a word, EGR is for environmental protection? Forced? The development and installation of power auxiliary equipment is mandatory, even if you have the ability to do it, you may not be able to pass the examination and approval of the National Sixth, because it is a regulation; Although laws and regulations are based on the name of environmental protection, the process is also indispensable.

And environmental protection and power, economy, durability and reliability have always been? Objection? Yes; Whether you agree or disagree, this is the naked fact before you. The relationship between environmental protection and the engine itself is, to put it bluntly, a state of complete conflict. From the domestic implementation of the country, from the carburetor to EFI and EGR, various environmental protection measures have been put on the car.

Therefore, after the above advantages, EGR must have disadvantages; Isn't the most obvious change from the time when there was no emission standard to now the so-called three-way catalyst? Because I drive more diesel engines.

For example, Isuzu covers almost many famous models, including 4JA/KOOC-0/,4JB/KOOC-0/,4JB/KOOC-0/T, 4JK/KOOC-0/,4J/KOOC-0/,RZ4E, 4KH/KOOC-0/,and other Toyota.

Therefore, for me, the most obvious feeling is the DPF added by the fifth country (urea has been added to the sixth country, and of course some models have already added urea).

Everyone saw how much trouble DPF was in the car. It is not an accidental phenomenon that machines of various brands and displacements are blocked for no reason. It is not known what kind of moth will appear in the sixth national congress, but there is no doubt that the stricter the emission, the greater the trouble of the engine and the higher the use cost.

Therefore, when there is an opportunity, it is better to buy a low-emission car; My mu-x was bought after the listing of National Five. Now it seems that it is really a happy thing to have no DPF.

Ok, let's continue to talk about EGR；; ;

EGR itself is a contradiction; It can reduce the emission of nitrogen oxides and the combustion temperature (the compression ratio of 3.0 L 4J 1 is lower than 2.5L 4JK 1, which is also the reason why it is easier to upgrade to the National Five); These are all advantages, so what are the disadvantages?

Let's talk a little;

For DPF, which is necessary for the national five-year plan, EGR itself is a big trouble; Because EGR will also aggravate the incomplete combustion of diesel oil when introducing exhaust gas to reduce oxygen content to achieve the purpose of cooling down; However, the combustion of a large amount of CO2 in the tail gas will cause a large number of particulate emissions; Isn't it a surprise! ? Because the purpose of adding DPF is to reduce particulate emissions, and EGR helps here, it makes the working conditions of particulate trap system for post-injection combustion treatment worse in the fifth national plan.

The result of introducing EGR into exhaust gas combustion is to produce more (particulate) soot; A large amount of smoke and dust will be discharged to DPF for treatment, which will shorten the life of DPF and reduce the regeneration mileage. A part will adhere to the cylinder wall, rub the piston, and finally be cleaned by engine oil.

The last part will pass through the EGR system, and finally enter the cylinder from the EGR pipeline, cooler, valve, intake manifold and valve, and participate in the combustion again, resulting in more soot, and so on.

The composition of soot is carbon black plus various X-acid salts, some of which have high hardness, making these small particles equivalent to hard abrasives. Of course, good engine oil can quickly disperse soot and dilute it into engine oil, but soot will still be blocked and worn by various systems before being dispersed and diluted by engine oil.

With the increase of mileage, there will be a lot of soot particles in engine oil. These oils containing soot are distributed in the whole engine system, from crankshaft to cylinder, including valve stem piston turbine. As the piston moves, these abrasives wear all the moving structural parts of the engine.

Therefore, if it is good for the whole engine to suppress the generation of soot to a certain extent, I don't need to talk about how to suppress it first.

The word soot may be abstract, but I'm sure I've seen the blackness of diesel oil. Even if you wash the oil twice before changing it, you will run out of the 4S shop after changing the oil again. It wasn't long before I looked at the scale and it was dark again. These? Black engine oil? The main reasons are cleanliness and smoke scattering.

Soot can also lead to partial blockage of EGR system, valve failure, decrease of cooler efficiency, serious valve wear, smaller internal diameter of intake manifold and other reasons leading to power output failure.

The important reason for this problem is that the EGR valve itself is located behind the air regulating valve (it can also be called throttle, although it is not called so on diesel engines); The air before entering the regulating valve is carefully screened by the air filter and is clean; From EGR, the exhaust gas discharged from the engine directly enters the valve chamber, that is, dense gas rich in soot.

Smelling it makes you feel refreshed, and can you cure SARS? .

In particular, the particulate emission of diesel engine and turbocharger will be combined for a long time, and there will be a little oil and gas combustion. If the engine is in bad condition, such as a little burning oil? Because this is normal in diesel engines, in these cases, let the exhaust gas directly enter the valve chamber for a long time, then we have the opportunity to think about what the problem will be like.

This is an exaggerated effect, but it can also be seen how serious it is.

If you want to say that EGR is not always there, but under various working conditions? That's right, but everyone knows the truth that a drop of water wears a stone. Look at your oil or look at the world behind the EGR valve. Your car won't be parked for three days and hung on the wall as a background.

And the result?

EGR exists objectively, and its function, advantages and disadvantages are also very clear. So you can find a way to deal with it yourself; There is no such thing as wanting a horse to run and not eat grass.

Regarding the negative content of EGR, I don't know why domestic web pages can't seem to find anything; If you want to know more, you can look at the external network. There are many things related to EGR. If your English is not good, you can Google it. In fact, you don't need to look at the text, just look at the picture and you can get the general meaning.