Appearance diesel engine in the mass consumer market forced the developers of such motors to bring them to world environmental standards. Diesel engines must effectively deal with exhaust gases, detaining elements that are dangerous for emission into the atmosphere. During the modernization of the exhaust gas system of diesel engines, diesel particulate filters began to be installed everywhere, which effectively clean the exhaust. During the operation of the diesel engine particulate filter becomes dirty and needs to be cleaned or replaced.

Table of contents:

What is a DPF particulate filter: task and principle of operation

As the name implies, the task of a diesel particulate filter is to keep soot particles as they appear in the exhaust. Soot accumulates in it, which is then burned off, thereby achieving a less environmentally harmful exhaust.

The principle of operation of the DPF filter is as follows:

1. Soot accumulates in the filter up to a critical moment, which depends on the pressure difference before and after the filter element;
2. When this pressure deviates from the norm, that is, the throughput of the filter decreases, the electronic engine control unit receives information about this and activates the afterburning mode of the accumulated soot;
   Please note: Depending on the engine manufacturer, the afterburning process may be activated under different conditions.
3. The afterburning process takes place at an increased rotational speed crankshaft and enhanced fuel injection, the command to which is given by the control unit;
4. This increases the temperature of the exhaust gases to values ​​at which soot burns out.

Despite the presence of a soot afterburning mode, nevertheless, it can accumulate in the DPF filter and not burn out. This is especially true for drivers who rarely operate the car at high speeds, moving mainly in the city.

Since the cost of the DPF particulate filter is quite high, drivers need to monitor these elements and clean it in a timely manner so as not to face the need for replacement.

Causes of clogged diesel particulate filter

Soot is a by-product of diesel fuel processing in engine cylinders. In exhaust gases, it is presented in the consistency of a fine powder, which is retained almost completely by the particulate filter mesh.

During the operating cycle, hydrocarbon particles that go into the exhaust do not burn in the chamber. Because of them, resinous deposits begin to form. This resin sticks together small soot particles, which leads to the formation of soot. In the place with soot in this soot, there are other elements of burning diesel fuel, as well as metal sulfates that occur in the exhaust due to the combustion of oil that has entered the cylinder.

Please note: Metal sulphates are a combustion product of fuel additives containing metallic elements. Especially a lot of metal-containing additives are found in universal oils that can be used for diesel and gasoline engines. This is one of the reasons why such oils are not recommended for regular use in diesel engines.

The result of the processes described above is the formation of soot deposits with particles of other elements that settle on the filter and do not burn out in the soot afterburning mode.

What determines the life of the particulate filter

Depending on how carefully the owner of the car approaches the issue of clogging of the particulate filter, the service life of the element is directly correlated. Also, the service life is affected by the number of activation of soot afterburning modes. The more often the car engine activates the soot afterburning mode, the less the diesel particulate filter will last.

Experts recommend to increase the service life of the particulate filter, especially if a car with a diesel engine is operated within the city, to clean this element at each MOT. It is especially important to do this if there are engine problems that can lead to the formation of massive deposits on the filter element.

Please note: A clean particulate filter is also economically efficient. If the filter is dirty, the engine power is reduced, which increases the engine consumption to drive the car with the same dynamics.

It is possible to increase the life of the particulate filter if you use special additives for diesel fuel. In automotive stores, you can find additives that are aimed at reducing the amount of carbon deposits formed as a result of the operation of the motor. This is achieved by maximizing the combustion of fuel in the engine cylinders, which leads to a reduction in the amount of soot in the exhaust gases. It is recommended to use such an additive at least once every 3000 kilometers of the car.

Also, the quality of the fuel used strongly affects the process of carbon deposits formation on the particulate filter, so you need to refuel with a high-quality diesel engine in order to maximize the life of this element.

How to clean the DPF particulate filter

There are two main ways to clean the DPF particulate filter from carbon deposits. The first implies the need to remove the filter element from the car, and the second involves performing actions directly on the car. Both methods have their advantages and disadvantages, so we will consider them separately.

Cleaning the particulate filter with removal

The complexity of this method lies in the need to dismantle the diesel particulate filter, as well as in the duration of the procedure. On average, it will take about 8 hours to clean the filter.

For cleaning, special particulate filter flushing fluids are used, which can be purchased at automotive stores. It is better to choose the compositions of proven brands, such as Luffe, Pro-tec, Liqui Moly and the like. These fluids are compositions of petroleum components and various additives that can dissolve soot deposits. Liquids are supplied in 5-liter canisters, on average, the entire canister is required for one flush. Canisters on top can have a place for attaching a hose, some of them have a hose included. The hose makes it easier to fill the particulate filter with flushing fluid.

The housing of the removed particulate filter must be completely filled with flushing fluid and left for the time specified in the instructions for use of the composition (about 8 hours). After that, it is enough to rinse the filter with a jet of water to wash off the remaining dirt, as well as the remnants of the cleaning agent.

Please note: Washing with water must be taken seriously as the cleaning agent is flammable and may ignite if exposed to exhaust fumes.

After washing the particulate filter with water, it remains to dry it and install it in place.

Cleaning the particulate filter without removing

The method of flushing the particulate filter without removing it is faster, since the work is carried out directly on the car. The design features of the filter allow you to supply cleaning fluid through the hole for installing a pressure or temperature sensor, after removing them.

It is important to note that a different composition is used to clean the particulate filter without removal. This is due to the fact that the work is carried out directly on the car, and there is no way to make sure that the oil products will be completely removed from the particulate filter. Therefore, a water-alkaline-based composition is used for cleaning. with flushing fluid. The liquid will allow after cleaning to neutralize the remaining alkali.

To flush the particulate filter without removing it, you will need to acquire a spray gun.

Please note: You can also find initially flushing liquids in aerosol cans. For the effective use of the liquid in the can, be sure to read the instructions for it.

Before washing the particulate filter, the car engine must be warmed up, after which it is necessary to wait until the temperature of about 40 degrees Celsius is established in the filter element. This must be done to improve the efficiency of the alkaline composition.

The composition is sprayed onto the particulate filter at a pressure of about 8 bar. In this case, the spraying process should be interval: 10 seconds the liquid is injected, then 10 seconds must be waited before injecting a new dose. Thus, it will be necessary to introduce about 1 liter of cleaning fluid. It is also important to rotate and move the spray probe in order to clean the entire particulate filter. After washing with an alkaline composition is carried out, pure water is sprayed in a similar way.

After cleaning the particulate filter with liquid agents, it is recommended to carry out the procedure for burning off soot residues by operating the car at high speeds for 20-30 minutes.

The principle of operation of the filter is based on the capture of solid particles that form at the outlet of the combustion chamber. The appearance of soot is justified by the wrong ratio of proportions combustible mixture: an excess of liquid fuel or a lack of oxygen. There are several situations like this:

• pollution air filter;
• incorrect valve clearance adjustment;
• cams are worn on the camshaft;
• injection timing not adjusted;
• poor fuel quality;
• nozzle leakage.

To clean the exhaust gases from soot particles, a special filter is installed in the design of the exhaust system, which is located between the exhaust manifold and the muffler. The shape of the soot structure resembles a metal flask with a core of multi-level porous walls in the form of cells, on which about 90% of soot particles settle.

Under the environmental standards Euro-4 and Euro-5, special cleaning elements (DPF and FAP) have been developed, with a different principle of operation and design features.

Features of the device of the ceramic matrix of the filter - in closed channels with a tapering octagonal or square section up to 1 mm, on the porous surface of which soot particles are retained. The filter device assumes the presence of sensors: air, temperature and differential pressure.

The design is an open version of the "soot catcher", which is optional, but rarely used due to imperfect design.

Closed soot trap - DPF (Diesel Particulare Filter)

The device is made with a catalytic coating of the matrix honeycombs. Filters must be replaced regularly. Rarely used is recovery by passive scrubbing with superheated exhaust gases. To burn out soot, it is necessary to pass crankcase gases with a limiting temperature reaching up to 600 ° C.

The principle of operation of the DPF type is the oxidation of carbon monoxide in the exhaust and the capture of soot particles. Filter operation is controlled electronic unit(ECU), the indication of which is located on the control panel.

FAP (Filter a Particles)

A feature of the FAP filter is the active regeneration of the matrix of the cleaning exhaust system. The principle is based on analogy with the DPF, but has the function of forced cleaning of the device. An additive with cerium is stored in a special container, which at the moment of ignition forms a temperature of up to 1000 ° C. This is enough to burn out soot accumulations in the cells.

Ways to remove the particulate filter

The service life of the filter is designed for a car run of up to 150,000 kilometers. Long-term operation is possible under ideal technical conditions. In practice, the period is reduced several times. This is justified by the use of low quality fuel, which leads to increased contamination of the particulate filter cells.

The first sign of contamination of the particulate filter is a noticeable decrease in engine thrust and vehicle acceleration dynamics.

In domestic operating conditions, there is a need to turn off or remove the filter. Characteristic signs of wear of the particulate filter are reflected in the operation of the car:

• floating idle;
• increase in fuel consumption;
• engine start intermittently;
• the control lamp for indicating glow plugs is on;
• at idle - an uncharacteristic sound (“hissing”);
• it is impossible to develop the maximum engine speed (above 3000 rpm).

You can visually determine the wear by the nature of the exhaust - a caustic black tint appears and the abundance of smoke increases.

It consists in reprogramming the controller firmware with an external device, with the appropriate program for the car model.

Flashing is carried out on diesel cars, in order to avoid turning on emergency mode when the fault code is diagnosed as a completely dirty filter. You can perform a flashing in several ways:

• install the program (corresponding to the car model) from the manufacturer;
• flash with a version of "unlicensed" software (associated with further risks);
• install the program of the control unit from the car, where the design does not provide for the presence of a diesel particulate filter by default (it is possible to change the functional characteristics).

The flashing method consists of several stages. First spend computer diagnostics to detect software errors. Establish the actual cause of malfunctions in the operation of the control unit system. Having diagnosed a malfunction in the operation of the particulate filter, the software is flashed. You can "get" to the file of the electronic control unit through the OBD connector or by unsoldering the BDM electronic chip. Correction of the program file will affect the performance of the car:

• the engine speed will increase in the driving mode, above 3000 per minute;
• the indication error on the control panel will be eliminated.

Firmware changes are approached with special attention, as it may affect the performance of the vehicle (associated with the electronic control unit). After the computer has erased the system software errors, the mechanical removal of the element is started.

Physical removal

The process consists in removing the filter can located between the muffler and the exhaust manifold. The craftsmen dismantle the exhaust system and cut out the section with the particulate filter, replacing it with a pipe with a flame arrester or welding in a plug. The method with a flame arrester is more relevant - the presence of sensors in the design allows you to avoid ECU errors. Work is completed within 2 to 6 hours - depends on design features car models.

Installing a particulate filter emulator

A “trick”, in the form of a particulate filter emulator, is installed in order to be able to reflash the control unit without changing the operation of the systems. The emulator "shows" the program controllers the presence of a filter in the exhaust system.

Such a “presence imitation” of a diesel particulate filter will not affect fuel consumption. The installed software in the control unit forcibly starts the FAP regeneration mode.

The method is based on the installation of a blende with sensors. The signals sent to the controllers cause the control unit program to function in the standard mode.

Replacing a clogged SF is more profitable from an economic point of view. A new original filter costs decent money. Mechanical removal or installation of the emulator will save money, but has its own characteristics that affect the operation of the car.

Positive Consequences

There will be no need for unplanned long trips to clean the filter. Pluses are observed in the operation of the control unit:

• software errors about the state of the particulate filter in emergency mode, on the instrument panel, are eliminated;
• oil consumption will decrease by turning off regeneration.

Removing a defective filter will have a positive effect on vehicle dynamics and traction. The engine will continue stable correct operation, the state of exhaust gases will change and the abundance of smoke will decrease.

Negative Consequences

Negative factors will manifest themselves during long trips in traffic jams and refueling the car with low-quality fuel. Permissible exhaust gas emissions will exceed the established environmental standards, which will make it difficult to pass technical control. A new vehicle may void its warranty (if the diesel particulate filter is removed). Trucks may ban entry to European countries where environmental standards for exhaust emissions into the environment are tightly controlled. The operation and movement of the vehicle is allowed with EURO-5 indicators.

Currently, Europe has the Euro-6 standard, and Russia has a less stringent Euro-5 standard, which regulates the emission of harmful substances into the atmosphere.

The above documents fix the limits on emissions of harmful substances for all types of cars operating on combustible fuels (diesel, gasoline), so in our article we will dwell in more detail on DPF particulate filters for cars using diesel (diesel oil) as fuel.

The ignition and combustion cycle of diesel fuel is significantly different from the combustion of gasoline. If high-octane mixtures burn out almost completely, then the diesel leaves a trace in the form of soot. This is what the particulate filter should remove from the exhaust.

Diesel particulate filters may have different names that vary from country to country and from brand to brand.

• So, DPF is an abbreviation for English. Designations Diesel Particulate Filter,
• FAP is an abbreviation that came from France - Filtre a Particules,
• And RPF is from RubPartikelFilter, from Germany.

Diesel particulate filter has one main purpose - to clean the exhaust gases of a diesel engine internal combustion from soot, which comes in the form of small mechanical particles ranging in size from 10 nm to 1 micron. A detailed analysis shows that these particles are compounds of carbon with water, heavy metals, sulfur and other elements.

Physically, the filter element can be made in the form of a separate housing installed in the exhaust gas system immediately after the catalytic converter. In some car models, the particulate filter and catalyst are combined into one housing.

The filter element is most often a hard material with a crystalline porous structure, for example, a ceramic matrix (silicon carbide or other compounds).

How to understand that the DPF filter is full

The ceramic matrix, which is responsible for cleaning exhaust gases from soot impurities, accumulates it in its pores.

This, over time, worsens its filtering properties, makes it difficult for exhaust gases to escape, which in turn creates an additional load on the engine, since the combustion chamber is not completely cleaned of combustion products.

Exhaust system with a particulate filter in a modern car

For this reason, it is required regular cleaning of the DPF filter(FAP or RPF) - the so-called regeneration.

The level of contamination of the particulate filter is monitored by special sensors.

• The most common method for assessing the contamination of a particulate filter is to analyze the pressure difference between the inlet and outlet of the assembly. The higher the difference, the higher the degree of contamination (gases have difficulty passing through the grate, which causes an increase in pressure at the inlet and a decrease in the outlet).

• Another type of sensors is oxygen, they monitor the level of oxygen in the exhaust mixture, respectively, the use of two sensors at the inlet and outlet of the particulate filter allows you to assess whether the content of other impurities has decreased or not, that is, whether purification has occurred or not.

On your display dashboard vehicle will show the corresponding error.

Most modern cars self-regenerating filters are used. They need a certain mode of engine operation to start the self-cleaning process.

When the machine is driven predominantly short distances without regularly warming up the particulate filter, this can cause it to become irreversibly filled with mechanical soot particles. In this case, without visiting the point Maintenance or even the salon of an official dealer is indispensable, since the error code can only be eliminated at an official service center.

Shutdown and regeneration

There are two types of particulate filter regeneration:

1. Passive.
2. Active.

The first type of regeneration is possible only on filters with a catalytic coating. Due to the fact that normal chemical reactions for burning soot require temperatures above 600 ° C, so-called catalysts are used to accelerate and facilitate the oxidation (combustion) reaction (substances that change the conditions for the occurrence of chemical reactions without their own consumption).

Thus, the use of a platinum-coated particulate filter reduces the temperature of soot burning to the level of 300 ° C. That is, the combustion of soot using a catalyst (catalytic coating) occurs during the natural operation of the engine, completely imperceptible to the user. There is no need to run any cleaning procedure.

Active type of regeneration involves modifying engine operation or adding special additives to the fuel in order to increase the temperature of the exhaust gases at the inlet to the particulate filter by up to 600 ° C. That is, this type of regeneration requires the participation or any active actions of the owner of a diesel car (manual start of the cleaning procedure or the addition of additives).

Built-in sensors analyze the current level of contamination of the filter element, and, if necessary, signal the user about a malfunction that has occurred (indication can occur on the dashboard or through the display of the on-board computer, depending on the model of the machine and its equipment).

Upon seeing a signal about a clogged particulate filter, the user can start the regeneration procedure in manual mode.

Procedures in various models cars and different manufacturers may differ in the sequence of actions, but the bottom line is that by changing the exhaust gas cycles, their temperature rises, which in turn heats up the ceramic filter grate to the desired level and burns soot.

If the procedure regeneration in manual mode for some reason does not clean the filter (simple wear of the equipment is possible, severe clogging of the ceramic matrix, frequent driving for short distances around the city, without a full warm-up of the exhaust system, when the filter cannot clean itself, etc.), the system can change error status. Now only an authorized service center can remove it.

The specialists of the technical service point, in turn, can offer to carry out a professional filter cleaning procedure (using chemicals, etc.) or completely replace the unit with a new one.

Due to the high cost complete replacement, some service stations offer a cheaper filter removal procedure with the installation of equipment that deceives the pollution sensor (the error can also be removed by software). This, of course, increases the emission of harmful substances into the atmosphere. We will leave the legality of the procedure on the conscience of the service station and car owners.

Should I remove the particulate filter?

On the one hand, removing the particulate filter is a one-time procedure that allows you to save on periodic replacement or cleaning of the unit, engine power increases slightly with the filter missing (since there is no resistance to exhaust gases). On the other hand, emissions are growing, and the likelihood of passing a regular state technical inspection reduces to zero.

The car will be able to drive with an error on the display. But it is worth bearing in mind that a clogged filter increases the resistance in the exhaust pipe.

Incorrect hardware removal of the node can cause an error due to which the engine refuses to start.

It is worth leaving the particulate filter or removing it completely - it is up to each owner to decide on their own. However, one should not lose sight of the fact that in the event of a negative result during the inspection, it may be necessary to install a new unit, which means that the removal procedure is an extra unjustified expense that only delayed the inevitable replacement procedure.

Based on materials from the Ukrainian magazine Avtomaster (a-maser.com.ua).

Andrey Bondarenko (Ireland) says:

The topic ABOUT PARTICULATE FILTERS, EGR, CATALYSTS, LAMBDA PROBES AND OTHER HARMFUL SYSTEMS deserves a lengthy discussion with detailed educational program, chewing and putting it on the shelves. It's going to be a long "song", but that's just what I wanted to say. Among experienced both car owners and servicemen, the attitude towards these personal belongings on a car is clearly negative. Empty, they say, all this, a whim, the bourgeoisie came up with, just to rip off the money. In general, it only prevents the car from working, eats up power and fuel. There are a lot of topics and recommendations about deletion, cutting, silencing, bypassing, etc. on the Internet and in print media.

In the event of a malfunction of the catalyst, EGR, particulate filter, etc., the first thing that a more or less experienced mechanic will offer is to get rid of them. How would you want to make the client pleasant, save money and all that. Well, and then after all, at the technical inspection they still won’t find fault!

But in vain. Firstly, the topic of exhaust control is technically no less interesting than increasing power and torque, there are many nuances and interesting relationships there, and working on these issues is not boring, as it might seem at first glance. Making a car run with zero CO and less HC emissions than a customer's breath is just as interesting as figuring out how to cut out the catalyst and put a decoy under the lambda probe.

And secondly ... take care of nature, your mother! If nature is not a pity, then at least they would save their breath. And then such a trash can will come with a cut out catalyst and a torn-out check engine light bulb, so stink that it brings tears to the eyes.

In general, it’s not good to fight against toxicity reduction systems, it’s wrong. Particulate filters and catalysts need to be changed, EGR work restored, and lambda probes are generally considered consumables, like filters, belts and candles. And what is expensive is ... you will have to pay for the happiness of using a car and at the same time breathing fresh air. This is a payment for the health of one's own and future generations.

You, of course, may say, “Well, this author, as if from another planet right, he argues, as if not from this world.” Only now I’m from this planet, I don’t have a spare, but those who reason and act differently should still be from another. Here everyone will be spoiled - and they will fly further ...

Was in the office today FIAT Doblo— diesel engine with a complaint about a burning particulate filter light bulb. The manager tells me: look what you can do there. Well, why look at the light bulb, you need a scanner - look at the parameters, error codes, make a forced regeneration of the filter, if possible. Of course, this is not done with a Nissan scanner, but with a Fiat one (well, or with some other one capable of doing this, but I don’t know such ones), so it’s out of the question. Well, you can still try to ride with the breeze for several kilometers, maybe it regenerates itself on the go ...

It didn’t help (I drove home and back, 40 km on a fast road), the light is still on, and the inscriptions “Antipollution” and “Particle filter clogged” are on the panel. I return and tell the manager that it didn’t help, drive him to the fiat dealer, let him at least read the error codes, maybe he will do a forced regeneration. And he says to me: “Strange, we recently cleaned the particle filter for him.” I'm wary: "How did you clean it?" It turns out that they took it off and… washed it with soap and water! And on the advice of a local fiat dealer. Tin, for several years now, these particulate filters have been massively used here, every second mechanic in dealerships, probably, has already attended a training on particulate filters in one form or another. It seems that they should already know that in particulate filters, exhaust gases are filtered through the pores in the walls of ceramic honeycombs (not along the honeycombs, as in catalysts, but through the walls!), Which pass gas molecules, but retain the smallest soot particles. Well, what's the water with soap?!

Impenetrable dullness…

Something our people somehow massively began to discover for themselves that private car- this is such a thing that you have to pay for, whatever one may say. Or walk then...

Went customers with the "problem" of the particulate filter. This is a problem of about the same order as the "problem with the brake pads." I explain: here all the readers (well, okay, almost all) are so literate and understand that brake pads are consumables, and there are no non-wear pads. The mass car owner is somewhat different. He takes the need to change the pads quite seriously as "well, now the brakes are broken, it's time to buy a new car." But then they are brake pads, they have been on the car for centuries, and particulate filters are a new technology, the manufacturer himself has not really worked it out, what can we say about a car service and its customers. In general, since at the moment I already have two cars with a clogged particulate filter, I am looking for solutions on the Internet, alternative uh… correct. For the right decision, no matter how sour it is for the car owner, is to replace the particulate filter that has exhausted its resource with a new one, add fuel additive (Eolys) to the tank and reset the system counters. Well, and, of course, make sure that the system functions as expected. Expensive? Yes, a thousand, or even two euros (a Peugeot is even noticeably cheaper than a thousand). But, you see, dear ones, you have to pay for the pleasure of driving a diesel engine that swallows an exhaustible hydrocarbon resource one and a half to two times more modestly, and even does not spit black smoke. No, of course, instead of a one and a half liter engine with a common rail, a turbine, an intercooler and a recirculated exhaust gas cooler, it is chic to put a four-liter naturally aspirated with an in-line injection pump under the hood so as not to lose in dynamics, spitting at passers-by and passers-by with clubs of black smoke. But that's only as long as you're the only smart one. And when everyone becomes like that, then at first there will be nothing to breathe. So what about alternative solutions. Of course, while such initiatives have not yet been banned, the people are thinking, first of all, in the direction of getting rid of the particulate filter.

Not so long ago, harmful catalysts were pierced with scrap, so as not to interfere with enjoying the entire spectrum of exhaust gases, and not some kind of fresh CO2 that trees absorb. Now, well, what's a diesel without a black exhaust? Straight, somehow undignified even ...

The most hit solution today is a specific chip tuning, in which the software modules involved in the operation of the particulate filter system are obtained from the software of the engine control unit.

Yes, the particulate filter is not just a fine mesh in the muffler, as the layman naively believes, it is precisely the system in which many elements are involved, up to the heating of the rear window. You don't believe me, you think I'm kidding? And here it is not. Now I will explain, although I have to start from afar.

If you put a soot screen in the muffler (and black smoke is soot particles), then it must be very fine, otherwise it will filter out little. Accordingly, than thinner filter- the sooner it will clog and require replacement. Even in a modern diesel engine with ultra-precise dosing of fuel supply, which was never dreamed of by a mechanical high-pressure fuel pump, there will be enough soot in the exhaust so that after several thousand kilometers the particulate filter is clogged tightly. Here my van is not old yet, already with a common rail, piezo injectors and hung with sensors everywhere, but no, no, and it puffs black smoke in the morning - there is just no particulate filter on it. To change the particulate filter by several hundred at each service and more often, the consumer, presumably, will not agree. What to do? It's not so bad, because soot is, in a sense, coal. Unburnt fuel. So, it can and should be burnt down so that the filter becomes clean again.

Ever tried to light coal with a match? It doesn't work out very well, does it? So it is with soot: in order for it to catch fire, it must be heated to a temperature of about 600 degrees. And for a diesel engine, unfortunately, the temperature of the exhaust gases is already lower than that of a gasoline engine, and even the exhaust turbine reduces it, because for its promotion (well, and warming up itself, of course) it takes not only kinetic, but also thermal energy of gases (the law of conservation of energy is inexorable, here you can’t throw a wire past the meter). Yes, and the catalyst is also there, yes, yes! And the EGR system, which is designed, just the same, to reduce the combustion temperature in the cylinders so that nitrogen oxides do not form. It's not easy…

The French, who were the first to attend to this whole problem, came up with the idea that a solution of the allanite mineral (the same Eolys) can be mixed into the fuel. The presence of small crystals of allanite, firstly, reduces the combustion temperature of soot (I will carefully assume that some kind of catalytic process is taking place, because I already vaguely remember how it really is, and I’m too lazy to look), and secondly, it loosens soot particles, which also contributes to their combustion. Accordingly, the temperature of soot combustion is already becoming a hundred degrees lower.

The filter is made of ceramic, in which there are pores sufficient for the passage of gas molecules, but retaining soot particles. Small pores, yes. I believe that they are not drilled manually, but some other process takes place, but it is most likely not easy, since the Chinese have not yet mastered particulate filters, which is why the price for them is appropriate.

In addition, soot particles burn out, but allanite crystals, alas, do not. Their accumulation limits the resource of the particulate filter in such a system. However, subject to the correct operation of the system, the filter life reaches an average of 150,000 km. With the price of a filter change (including Eolys refill and associated labor costs) of 750 euros (this is for the Peugeot 407) and a fuel price of 1.50 euros / liter (we live, huh!), This is equivalent to an increase of 0.3 l / 100 km in fuel consumption fuel. Not so scary, right?

There are particulate filter systems that do not use fuel additives. There, an increase in the temperature of the exhaust gases, among other measures, is achieved by injecting more fuel. It is injected either at the end of the power stroke phase (so that it burns out already in the catalyst, which stands right in front of the fuel filter), or the fuel is injected directly into the exhaust manifold with a separate injector. It's not hard to guess that the injected fuel is taken from the tank and paid for from the same pocket that would otherwise pay for a diesel particulate filter change. However, even here the resource of the particulate filter is not infinite, since the filter is inevitably clogged with fireproof particles. These particles are taken, if not from low-quality diesel fuel (with a high sulfur content), then from inappropriate oil. For oil always penetrates into the cylinders, even in an unworn engine, and the oil contains additives. This is why diesel particulate filter engines are mandated to use special oils, in which the content of fireproof additives is less.

There is another type of filter, in which the ceramic core plays the role of both a filter and a catalyst, due to which, again, it is heated (unburned or additional fuel burns on the catalyst). Of course, such a filter will be the most expensive, because it uses precious metals in a fairly immodest amount.

In order not to provide an increase in the temperature of the exhaust gases only due to the excess injected fuel (after all, we switched to diesel in order to save fuel in the end!), Other tricks are also used. The air entering the engine bypasses the intercooler to be hotter at the intake, the exhaust gas recirculation is turned off so that it burns hotter, the filter regenerates when the engine is running under load, and not at Idling. Plus, this load on the engine is created additionally, but in such a way that the driver does not notice: the air conditioner compressor turns on, and the generator is loaded with additional consumers such as fans on the radiator (at the same time, the air conditioner condenser will blow over and temperature regime provide the engine), glow plugs, auxiliary heater thermocouples (that's why the passengers will not feel that the air conditioner has worked!) and window heating.

You didn’t forget: I was going to prove here that glass heating is involved in the operation of the particulate filter system? And now imagine that this whole complex system that controls not only the engine, but also other parts of the car, gets playful handles of a chip tuner who did not participate in the development of this software and does not have its source codes (who will give them to him!) . This system is already not without bugs, there are enough software bugs in it (let's not forget that it also ensures the performance of the main function of the engine - to issue Newton meters to the output!), And if they start picking out modules from it by typing ...

No, sometimes things go quite smoothly. In the end, if then some glitches come out, then who knows why they are there, on an old car. Maybe not because the software was picked up ... Further, since not all chip tuners specify that in addition to chip tuning, it would also be necessary to remove the filter itself physically, some owners calm down on this. Why, the light on the panel doesn’t interfere anymore, the car is moving, the problem seems to have been solved. And for everything about everything, a maximum of 500 - 600 euros (this is for cool tuners who swear that everything will be ok) or 200-300 for simpler offices. The most resourceful buy a Chinese clone of a flash programmer, download a pirated copy of chip tuning software, and use this equipment to reprogram their control unit in a car for some miserable 50 euros. If the nature is risky, and new block management money set aside just in case, why not? After all, no one dies from this. True, the filter that has not been removed from the exhaust system will not be able to regenerate in any way, the control system forgot about it. And after a few thousand, he will remind himself of himself with a completely caulked exhaust.

That's what I think, but what is it that I now have a Ford Focus with a tightly clogged filter, even almost nothing comes out of the exhaust pipe, but I still drove as if nothing had happened, according to the owner. Maybe it has already been tuned? But how to check now?

Again, Peugeot has still not had a problem picking out the filter - its body is detachable, and it is relatively easy to get to the core with a hammer and chisel. But on the same engine, which is on Ford and Volvo, the particulate filter is welded into a single one-piece housing with a catalyst, and even with a bent pipe at both ends - do not approach. Cutting in half, picking out the filter and then brewing it back (and even with high precision, otherwise you won’t screw it back to the engine so that it doesn’t siphon anywhere) - it will turn out either at a price comparable to a new one, or in terms of the artist’s income comparable to Eastern European salaries. Doing business with such prices will not work for a long time - you will stretch your legs.

So I removed the filter and gave it to the owner: if you want to suffer, go ahead, cut, dolby, cook. He promised to bring it tomorrow, then I will already have trouble installing it in place ...

Enthusiasts also invented a method for washing the filter with Karcher soap and water. To say that it does not help at all, I will not say: it helps for a while. They washed it in the garage recently, the car has been driving for a whole month. Maybe someone has more trains. Moreover, we don’t know if the filter was clogged with soot due to a malfunction in the system and stopping regeneration, and not with allanite or sulfur.

So the particulate plug was knocked down, the rest was regenerated (for example, the malfunction suddenly went away by itself) in the process of driving, and the satisfied owner dashed off for several more years, trumpeting on the forums about how he deftly did not let himself heat up greedy mechanics and dealerships. So let's all wash the filters. Saw, Shura, saw...

After all, the more you know, the more you doubt, and the more you are inclined to discard questionable solutions that are so delightfully cheap and simple from the point of view of someone who is not in the know. But on the other hand, the more you know, the easier it is for you to calculate and plan ahead. And then the replacement of the particulate filter or brake pads will no longer be an unpleasant and expensive surprise, but just one of the usual expenses. For the luxury of breathing clean air and not walking, I can pay.

We have a Primastar van, as usual, - diesel (the probability of meeting a gasoline van in our area is lower than meeting a Ferrari Testarossa; I have seen Testarossa, but I have never seen a gasoline van). It goes badly, the engine malfunction light is on, a bunch of error codes and, in general, the state is running. I sort out the problems one by one, and the EGR system error remains, which stubbornly appears after erasing the errors and subsequent test drives. The average mechanic or advanced car owner will tell you to change the EGR valve. Especially considering that it is electric, its malfunctions are not uncommon, and the mileage at the time of repair is a little less than one and a half hundred thousand kilometers. Moreover, in addition to this valve in the EGR system on this engine Renault F9Q is like nothing else: a valve and a pipe from the exhaust manifold. An advanced mechanic or a reasonable diagnostician will say that you need to smoke a manual and diagrams and check the valve and wiring for serviceability before rushing to replace a part at a price of well over a hundred euros.

After all, what distinguishes a diagnostician from a monkey-mechanic is the ability to distinguish a faulty part from a serviceable one not only by eye and touch, but also by the instrumental and instrumental method.

Let's start by checking the valve for the simple reason that the engine control unit here is securely closed with a metal casing screwed on with bolts with shear heads. This is not to mock the diagnostician, as you might think in your hearts, but in order to increase the insurance rating for protection against theft and, accordingly, drive the van into a lower insurance group - insurance is cheaper. Repairs, of course, will turn out to be more expensive, but all vans must be insured every year, and only a few must be repaired. For a corporate client with hundreds of cars, the gain is obvious, but for a private client - how lucky. Well, and the valve, here it is - right on top of the motor, you just need to remove the air filter housing and the three bolts that hold the valve (in the picture the valve has already been removed, at the top right, and in the center there is a hole in the manifold where it is inserted).

How does the manual suggest to check the serviceability of the valve?

Measure four resistances, between pins 1 and 5, 2 and 4, 4 and 6, 2 and 6. If the resistances do not go beyond the permissible values ​​\u200b\u200b(and the spread of permissible values ​​\u200b\u200bis given like “from 800 to 3600 ohms at a temperature of +20”), so the valve is good. At this point, I clearly realize that the author of the manual holds him, the reader, for the same monkey, but different from the rest of the garage monkeys in the ability to read and use a multimeter.

Particularly touching is the indication of the temperature at which measurements are to be made. So I imagine how the diagnostician carries the removed valve to the “Measurement Room”, in which a stable temperature of +20 is maintained in winter and summer, leaves the valve there for several hours so that it cools down evenly or warms up to the desired temperature, and then resistance measurements and writes down on a piece of paper. You think that I am exaggerating, but in fact, in a training video on working on systems common rail, which I looked at Peugeot, it was supposed to allocate a special room in the workshop for these works, where crystal cleanliness would be maintained, and before any disassembly of parts and components of the power system, they would need to be washed and cleaned with a special (!) liquid. This also applied to the replacement operation. fuel filter, by the way.

In fact, everything is much simpler and at the same time more complicated. The great commander Suvorov said: "It is hard in learning - it is easy in battle." In a car service, it is customary to recruit those who were easy to learn. That somewhere is justified in some way, as long as it comes to replacing filters, pads and oil ... however, there are subtleties in replacing pads that monkeys do not know. In fact, changing the oil is also not always possible for them. Yes, and filters ... Well, okay, they have to work somewhere, don't they? In the end, the activity of unskilled specialists in a car service creates at least half of the problems that the diagnostician then solves. Let's return to the task of checking the health of the EGR valve.

Here he is handsome:

You need to start with the concept of why it is needed here and how it works. A diesel engine, unlike a gasoline engine, has an excess of oxygen in the combustion chamber during the power stroke cycle when the fuel is burning. A gasoline engine works best when the mixture of air and gasoline is supplied at a ratio of 14.7 to 1. There will be more air - the mixture will not ignite from a spark. There will be little - it will also not be able to burn, the fire will suffocate from lack of oxygen.

But in a diesel engine, no matter how much air you pump, the fuel in it will catch fire anyway, because the air is compressed, heated more and ignites the fuel without any spark. It would seem that it’s bad: pump air in excess, you don’t have to pay for it. And the bad thing is that there is a lot of nitrogen in the air, in fact, most of it is nitrogen. Nitrogen does not form oxides at normal temperatures, but at high temperatures it does not even form. And these nitrogen oxides fly out into exhaust pipe. Now we have nitrogen oxides NOx in the air, we add water H2O from the clouds to them and we get nitric acid in the form of acid rain. And do we need it? If we limit the intake of air with a throttle valve, we lose in efficiency and momentum (because now it becomes more difficult to suck air into the cylinders), but why then a diesel engine? Therefore, the problem is solved by replacing part of the air entering the cylinders with exhaust gases from the exhaust manifold. It looks a little wild, from the point of view of a petrolman or an athlete, because we are replacing clean air with dirty gases, it will burn worse! In fact, the remaining oxygen is enough for normal combustion in most modes, and at idle and under full load, the EGR is turned off.

And then I read here one English diesel specialist, so he said on his website: “But I don’t even know why they put this EGR, there’s only one harm from it.” A person signed his own professional illiteracy, ah-yay-yay!

The proportion of exhaust gases entering the cylinders must be regulated accurately enough. If you don’t give enough exhaust gases, nitrogen oxides will go out, if you bend the stick in the other direction, the engine will start to choke and smoke soot, which is also not good. To do this, you need to have a valve that can open to a different section, more or less, and you need to somehow measure how much gas actually came in. The latter function is taken over by an air mass sensor similar to the MAF. And then, it would seem, why is it needed, on diesel engines? This sensor, of course, measures how much clean air has passed, but the bottom line is that when the EGR valve is opened and exhaust gases enter into intake manifold, the consumption of clean air becomes less than it should theoretically be at a given speed, temperature and pressure. It is this difference between the calculated and actual value of the MAF signal that allows you to calculate how much exhaust gases have entered and correct the position of the EGR valve. That is, we have feedback and can control the system more accurately. MAF is thus an unobvious but integral part of the EGR system on modern diesel engines.

But I got very distracted, actually I just wanted to show how smart I am and how cool I can check the EGR valve without any manual)). So on the valve we have a connector and five wires on it. Two wires - thicker section and three - thin. Without any diagram, I'll tell you that two thick wires are the valve's electric drive, and three thin wires control its position. Remove the valve and

on the pins from two thick wires, we boldly supply 12 volts, “plus” and “minus”. If there is an electric motor in the valve, it rotates to one of the extreme positions, and when the polarity is changed, to the other. But while I was cleaning this valve from carbon deposits (yes, also a possible reason), I noticed that its damper is spring-loaded in the closed position and opens if you pry with a screwdriver. So here we have not an electric motor with polarity reversal control, but an electromagnet, and it is controlled by changing the duty cycle of the signal.

So if you apply 12 volts here, then the damper will immediately jump all the way to the open position (we determine the polarity by typing, nothing will happen to him). It jumps, does not stick, opens and closes, which means that the power part of the valve is in order. Now position control. It can be a potentiometer, or maybe a Hall sensor. This means that the test will be faster and more reliable if the valve is connected back to the car and the ignition is turned on. Now we poke a voltmeter along thin wires: on one 5 volts - it looks like power, on the other millivolts are small, twenty with a tail - this is mass, on the third 1.06 volts - it must be a signal of how the signal value smoothly changes to 4 volts (ideally, you need a good oscilloscope to see the wear of the potentiometer track or some other signal glitches). That's all! The valve is in order, 100%.

A few years ago, I was a staunch fan of gasoline engines and believed that diesel had a place only on commercial vehicles. But gradually, as the rides on different machines, the progress of technology and, importantly, mastering it in terms of repair and diagnostics, I have not changed my views drastically, but, at least, I put diesel on the same level as a gasoline engine. For a diesel engine is not only more economical (as it has always been) and no longer delivers unpleasant sensations with noise and vibrations (some of them are already very pleasant to the ear), but often already subjectively wins in terms of dynamics due to the assertive moment at medium speeds. Subjectively, because although according to the figures the acceleration time to hundreds and the maximum speed of the top petrol versions are better, this acceleration is achieved (after all, acceleration is practically more interesting for us than the maximum speed), accompanied by the roar of the engine, twisted to the red zone of the tachometer, and passers-by, frightened turning around head to the source of the noise. As youth fades, the effect this produces on others and passengers ceases to please, however ...

In fact, the latest three-liter diesel engines have caught up in terms of power and torque with the five-liter eights of the recent past, and at the same time remain almost more economical than the two-liter inline fours of the same years. Yes, and tiny one and a half liter diesel engines, in general, carry a golf-class car quite acceptable (for an average exemplary family man) and, as already existing experience shows, they have a not so small resource even in conditions of complete neglect of maintenance.

Well, and finally, the price of fuel and taxes hammer in the last nail - with almost the same dynamics, the top versions of petrols cost twice or three times as much to operate, and the idea of ​​​​buying such a car begins to seem silly. However, I still do not promise, because the prices for used options can be very tempting.

Andrey Bondarenko, Notes from Ireland.

Magazine "Automaster" No. 6.7 -2013 (a-master.com.ua)

Particulate filter with catalytic coating.

Reducing the emission of soot particles is today one of the most difficult tasks in the field of purification of exhaust gases (EG) of diesel engines. In addition to measures aimed at reducing the formation of soot during the combustion of fuel directly in the engine, special attention is paid to the filtration of gases at the outlet from it.

One of the effective ways to clean gases from soot particles is their retention through special filters. The most widespread are systems consisting of an oxidizing type converter and a particulate filter. In addition, the filter allows you to almost continuously burn out the retained soot without introducing special additives into the fuel.

The latter property is achieved both by using a special design of the filter, and as a result of its maximum approximation to the engine.

Usually, at our services, repairs come down to cutting out the filter and trying to reprogram the control unit. Let's try to figure out what we cut out using the example of a VW particulate filter.

During the combustion of diesel fuel, substances of various types and types are formed. The operation of a cold engine is usually accompanied by emissions of white or gray smoke created by droplets of unburned or partially oxidized hydrocarbons, and emissions of aldehydes, the presence of which in the exhaust gas is easily recognized by their characteristic odor.

At the diesel outlet, there are not only gaseous substances, but also solid formations, the size of which is commensurate with the size of dust particles. These formations, collectively known as "particles" (Partikel), are considered harmful to human health and polluting the environment.

Spent gases diesel.

FORMATION OF HARMFUL SUBSTANCES IN THE PROCESS OF FUEL COMBUSTION

The intensity of the formation of harmful substances, and especially soot, largely depends on the parameters of the combustion process of fuel in diesel cylinders. The course of the combustion process is influenced by both the design parameters of the engine, and the composition of the fuel and atmospheric conditions.

The figure below lists all the initial components of the air-fuel mixture and the components of diesel exhaust gases resulting from its combustion.

The individual components of diesel exhaust gases have different effects on the environment and human health.

Only oxygen, nitrogen and water, which are part of the atmospheric air, are completely harmless.

A natural component of atmospheric air is carbon dioxide (carbon dioxide), but its concentration in the air is close to the limit values.

Carbon dioxide is not poisonous, but increasing its amount in the atmosphere can lead to a greenhouse effect. Substances harmful to human health include carbon monoxide, hydrocarbons, sulfur dioxide, nitrogen oxides, soot particles and more than three dozen components of automobile exhaust.

HARMFUL COMPONENTS OF THE EXHAUST GASES

Carbon monoxide (CO) or carbon monoxide is produced when carbon-containing fuels do not burn completely due to lack of oxygen. It is a colorless gas, odorless and tasteless. It is toxic and especially dangerous: it absorbs oxygen from human blood, which can lead to oxygen starvation of the brain and death.

The term "hydrocarbons" refers to numerous compounds of various types (for example, C6H6 or C8H18), which are formed during the incomplete combustion of fuel.

Sulfur dioxide is formed during the combustion of fuel containing sulfur. It is a colorless gas with a pungent odor. Currently, efforts are being made to reduce the sulfur content of fuels.

Nitrogen oxides (for example, NO, NO2, …) are formed during the combustion of fuel in the engine under conditions of high pressures and temperatures, as well as in conditions of excess oxygen

Soot is formed as a result of incomplete combustion of fuel with a local lack of oxygen.

PARTICLES

The concept of "particles" includes solid or liquid formations having small dimensions. They can form as a result of wear of parts, grinding and erosion of materials, and condensation of liquids. In particular, they are formed during the incomplete combustion of fuel and oil. In the above cases, particles are formed various shapes, quantities and structures. Particles are classified as harmful substances, since, due to their small size, they move along with gases and, if they enter the human body, can harm it.

SOOT PARTICLES

When diesel fuel burns, soot particles are formed. These are microscopic carbonaceous particles with a diameter of approximately 0.05 microns. The core of the particle consists of pure carbon, and various hydrocarbon compounds, metal oxides and sulfur are adsorbed on it.

Some hydrocarbon compounds are believed to be hazardous to human health. The specific composition of soot particles depends on the working process used in the engine, its operating modes and fuel composition.

THE PROCESS FOR FORMATION OF SOOT PARTICLES IN DIESEL

The formation of soot in diesel depends on a number of processes that determine the combustion of fuel. These are the processes of air supply, fuel injection and flame propagation.

The quality of fuel combustion is determined to a large extent by the process of formation of the air-fuel mixture. Due to the lack of oxygen in some areas of the combustion chamber, an overly rich mixture is formed, the combustion of which cannot be complete and is accompanied by the formation of soot particles.

The number and mass of particles depend, in principle, on the quality of the mixture formation and combustion processes occurring in the engine. Fuel system with unit injectors ensures fuel injection at very high pressure and with a timed supply that meets the requirements of the engine. This creates conditions for increasing the efficiency of the combustion process and reducing the formation of soot particles. However, high injection pressures and the corresponding increased fineness of fuel atomization cannot provide sufficient refinement of soot particles. Measurements of the sizes of these particles showed that their size distribution practically does not depend on the method of mixture formation, i.e., it is very close for engines with a vortex combustion chamber and for engines with direct injection through the Common Rail system or unit injectors.

CHANGING THE ENGINE DESIGN

It is possible to reduce the emission of harmful substances by introducing measures related to changing the design of the engine itself. Successful optimization of the workflow can lead to a significant reduction in the formation of harmful substances.

These activities include:

Optimization of the shape of the intake and exhaust channels, creating a directed movement of air in the combustion chamber.

Increasing injection pressures, for example, by means of unit injectors;

Optimization of the combustion chamber, in particular by reducing "harmful" volumes and the shape of the recess in the piston.

EXHAUST GAS CLEANING

Emissions into the atmosphere of soot particles formed during the combustion of fuel can be reduced by carrying out measures to clean the exhaust gases after they have been released from the engine cylinders. In this case, they mean, first of all, a filtration system capable of retaining soot particles.

There are two types of regeneration of particulate filters: with the use of additives to diesel fuel and using a catalytic coating of the filter element. Below is a description of the device and the principle of operation of the catalytic particulate filter.

GAS PURIFICATION SYSTEM USING K ADDITIVESDIESEL FUEL

This system is used on vehicles where the particulate filter is located at a relatively large distance from the engine. In this case, the temperature of the exhaust gases at the inlet to the filter is insufficient to burn out soot in it, so fuel additives are used that reduce the ignition temperature of soot to the required level.

GAS CLEANING SYSTEM WITH PARTICULATE FILTER,COATED WITH CATALYTIC

This system is used on vehicles with a particulate filter located close to the engine. In this case, the temperature of the gases on the short path to the filter remains high enough to burn the soot.

1 – Control unit in dash panel insert J285

2 - Engine control unit

3 - air flow meter

4 - diesel

5 - temperature sensor in front of the turbocharger G507

6 - turbocharger

7 - temperature sensor in front of the particulate filter G506

8 - oxygen sensor G39

9 - particulate filter

10 - pressure drop sensor 1 on the particulate filter G450

11 - temperature sensor after the particulate filter G527

12 - silencer.

PARTICULATE FILTER

The catalytic coated particulate filter is installed after the turbocharger in close proximity to the engine. In this case, a catalytic coated particulate filter is used, which is structurally combined with an oxidizing type converter. Thus, having a common housing, the unit performs the functions of both a filter and a neutralizer.

The particulate filter traps the soot particles contained in the exhaust gas. The function of the neutralizer is to oxidize hydrocarbons (HC) and carbon monoxide (CO) to water (H2O) and carbon dioxide (CO2).

DEVICE

The particulate filter matrix is ​​a honeycomb structure made of ceramic based on silicon carbide. The ceramic matrix is ​​enclosed in a metal case. It is pierced by many parallel channels of small cross section, closed alternately on one or the other side. Therefore, inlet and outlet channels are distinguished, separated by filtering walls. The filter walls are made of porous silicon carbide. They are coated with a mixture of aluminum and cerium oxides, which act as a support for the catalyst, which is used as a noble metal - platinum. A catalyst is a substance that promotes a chemical reaction, but does not itself change and does not form new compounds.

OPERATING PRINCIPLE

Since the filter channels are alternately closed on the inlet and outlet sides, gases containing soot particles are forced to pass through the porous silicon carbide walls. In this case, soot particles are retained in the intake channels, and the gas freely passes through the pores of the channel walls.

PARTICULATE FILTER AREAS WITH CATALYTIC COATING

The particulate filter must be relatively long in order to capture a sufficiently large amount of soot. In addition, it must contain sufficient amount of platinum to ensure catalytic action. The catalytic coating is distributed along the length of the filter not evenly, but in zones. There is much more platinum in the anterior zone than in the posterior zone. The uneven distribution of platinum in zones has the following advantages.

During normal engine operation, the front of the particulate filter heats up faster than the rear. Therefore, a relatively large amount of platinum in this zone contributes to the acceleration of its catalytic action. At the same time, they talk about good starting qualities of the particulate filter.

During the regeneration process, soot burnout is accompanied by strong heating of the back of the filter. But high temperatures lead to the gradual destruction of the platinum layer. Therefore, it is possible to save on expensive platinum by reducing the thickness of the coating in the rear zone of the filter.

On the other hand, a decrease in the amount of platinum in the rear zone is justified by filter aging processes. During the operation of the car, more deposits that reduce the catalytic effect of platinum accumulate in the rear of the filter than in the front of it.

FILTER REGENERATION

To prevent an excessive increase in filter resistance and a decrease in its performance, it is necessary to free it from soot from time to time.

During the regeneration process, the soot particles accumulated in the filter are burned out (oxidized). A distinction is made between active and passive regeneration of a catalytically coated particulate filter. For the driver, the regeneration process proceeds imperceptibly.

The filter walls are made of porous silicon carbide.

They are coated with a mixture of aluminum and cerium oxides, which act as a support for the catalyst, which is used as a noble metal - platinum.

A catalyst is a substance that promotes the flow of a chemical reaction, but does not itself change and new compounds are not formed.

PASSIVE REGENERATION

With passive regeneration, soot is burned off continuously and without special intervention in the engine management. When the particulate filter is located close to the engine, the temperature of the gases entering it can reach, for example, when driving on a motorway, about 350–500 ° C. In this case, reactions occur, as a result of which soot particles interact with nitrogen dioxide and turn into carbon dioxide. This multi-stage process proceeds continuously over a layer of platinum, which acts as a catalyst.

OPERATING PRINCIPLE

NOX + O2 form NO2

Nitrogen dioxide (NO2) reacts with carbon (C) of soot particles. The result is carbon monoxide (CO) and nitric oxide (NO).

NO2 + C form CO + NO

Carbon monoxide (CO) and nitric oxide (NO) react with oxygen (O2) to form nitrogen dioxide (NO2) and carbon dioxide (CO2).

CO + NO + O2 form NO2 + CO2

ACTIVE REGENERATION

With active regeneration, soot particles are burned off in the high temperatures resulting from the directional control of the engine. The operation of the vehicle in the city is characterized by low engine loads, and the corresponding low exhaust gas temperatures do not provide passive regeneration of the particulate filter. At the same time, soot particles are not removed from the filter and clog its channels. When a certain amount of soot accumulates in the filter, the process of its active regeneration starts, proceeding according to the commands of the engine control system.

The active regeneration process lasts approximately 10 minutes. In this case, the exhaust gas temperature rises to 600÷650°C, which is sufficient for the oxidation of soot to carbon dioxide.

OPERATING PRINCIPLE

During active regeneration, the soot particles are burned off by the high exhaust gas temperature. In this case, forming soot particles, carbon combines with oxygen, forming carbon dioxide C + O2 form CO2.

PRINCIPLE OF FILTER OPERATION DURING ACTIVE REGENERATION

Soot particles accumulate in the intake ducts.

The need for active regeneration is determined by the engine control unit based on signals from the air mass meter, exhaust gas temperature sensors before and after the particulate filter, as well as the differential pressure sensor on it. A clean particulate filter offers little resistance to gas flow.

A filled particulate filter has a high resistance to the flow of gases.

When the filter is filled with soot to a certain value, the engine management system starts the process of active regeneration

FUNCTIONS OF THE ENGINE MANAGEMENT SYSTEMACTIVE REGENERATION

The degree of filling of the filter with soot is determined by the control unit by its gas-dynamic resistance.

High filter resistance is a sign of the accumulation of the maximum allowable amount of soot in it, so the engine control unit starts the process of active regeneration. This performs the following functions:

Exhaust gas recirculation is stopped in order to increase the combustion temperatures of the fuel;

In order to increase the exhaust gas temperature, an additional injection of fuel supplied after the main dose is carried out, namely, when the crankshaft is rotated 35 ° after TDC;

The air supply to the engine is reduced by means of an adjustable throttle valve with electric drive;

The boost pressure is maintained at a level at which the driver cannot notice that the engine is in recirculation mode.

These measures allow you to briefly increase the temperature, the soot accumulated in the filter is oxidized to carbon dioxide. After active regeneration, the filter's ability to retain the soot contained in the exhaust gas is fully restored.

SOOT FILLING DEGREE

The engine control unit constantly monitors the degree of filling of the filter with soot, calculating its gas-dynamic resistance. In this case, the volume flow of gases is correlated with the pressure drop across the particulate filter.

FILTER PRESSURE DROP

The differential pressure across the particulate filter is determined by means of a differential pressure sensor.

The engine control unit determines the gas-dynamic resistance of the particulate filter in relation to the differential pressure to the exhaust gas volume flow. And the gas-dynamic resistance of the filter is a measure of its filling with soot.

EXHAUST VOLUME

The exhaust gas volume flow is calculated by the engine control unit from the engine inlet air mass flow and the exhaust gas temperature before the filter.

The exhaust gas mass flow is practically equal to the air mass flow, which is determined by means of a flow meter. The exhaust gas volume flow, however, depends on the temperature.

The latter is determined by means of temperature sensors before and after the particulate filter.

Based on the exhaust gas temperature, the engine control unit can calculate the exhaust gas flow rate from the air mass flow rate.

FUEL INJECTION WHILE COASTING THE VEHICLE

Under extreme driving conditions in the city with a sharply changing engine load and frequent coasting, special measures must be taken to regenerate the filter. Since no fuel is normally injected into the engine cylinders during coasting, the exhaust gas temperature does not rise to the level required for filter regeneration.

Therefore, to regenerate the filter during coasting, increased doses of fuel are injected, namely, when the crankshaft is rotated 35 ° after TDC. Due to the absence of the main dose of fuel injected when the piston is close to TDC, the fuel that enters the engine cylinders during the expansion stroke burns the fuel vapor in the particulate filter, and the heat released in this case ensures that the temperature of the exhaust gas rises to the temperature necessary for its regeneration; the fuel supporting regeneration is regulated by the signals of the temperature sensor Exhaust gas installed after the particulate filter.

The pump-injector drive cams for diesel engines with a particulate filter have a special profile that provides the injection of additional doses of fuel.

In this case, the movement of the plunger corresponding to the supply of fuel ends later than for engines without a particulate filter. Due to this, the active stroke of the plunger remains for supplying an additional dose of fuel with a sufficiently large delay.

DIFFERENTIAL PRESSURE SENSOR TO PARTICULATE FILTER,USING THE SENSOR SIGNAL

This sensor is used to measure the exhaust gas differential pressure across the particulate filter. Its signals are used in conjunction with the signals from the temperature sensors before and after the particulate filter, as well as with the signals from the air mass meter to determine the degree of filling of the filter with soot.

CONSEQUENCES OF NO SENSOR SIGNAL

In the absence of a signal from the differential pressure sensor, the particulate filter is regenerated periodically according to the mileage or the time the vehicle has been used. However, regeneration according to this principle cannot be reliable for a long time.

Therefore, after a certain number of regeneration cycles, the diesel particulate filter warning light comes on first, and then the glow plug warning light starts flashing. The driver is thus warned about the need to contact a service company.

SENSOR DEVICE

The differential pressure sensor 1 has two fittings: one of them is connected to the pressure measuring tube before the particulate filter, and the other after it. Inside the sensor there is a membrane with piezoelectric elements, which is affected by the pressure difference.

OPERATING PRINCIPLE

PARTICULATE FILTER CLEAN

If there is very little soot in the filter, the pressures before and after it are almost equal. In this case, the membrane with piezoelectric elements is in its original position.

FILTER FILLED WITH SOOT

Due to the increase in filter resistance when soot accumulates in it, the exhaust gas pressure in front of the filter increases. The exhaust gas pressure after the filter remains virtually unchanged.

The membrane sags in accordance with the pressure difference acting on it. The deformation of the membrane entails a change in the ohmic resistance of the piezoelectric elements included in the bridge circuit. The output voltage of the bridge is amplified and converted in the electronic circuit

sensor, the signal from which enters the engine control unit. Based on the value of this signal, the engine control unit determines the degree of filling of the filter with soot and, if necessary, issues a command for its regeneration.

TEMPERATURE SENSOR BEFORE PARTICULATE FILTER

The temperature sensor upstream of the particulate filter contains a PTC (Positiver Temperatur Coeffizient) resistor. That

is the resistance of a resistor increases as its temperature rises.

This sensor is used to measure the exhaust gas temperature at its location in the exhaust pipe before the diesel particulate filter.

The signals from the temperature sensors before and after the particulate filter are used by the engine control unit to calculate the exhaust gas flow rate and then the amount of soot filled in the filter.

An accurate determination of the degree of filling of the filter with soot is only possible with the combined use of signals from the air mass meter, exhaust gas temperature sensors before and after the filter, as well as the exhaust gas differential pressure sensor across the filter.

In addition to the signals from the above sensors in the control system, an alarm is provided, which is used to protect the particulate filter from excessively high exhaust gas temperatures.

After the signal from the temperature sensor in front of the filter stops, its regeneration is carried out periodically according to the mileage or the time the car has been in operation. Since regeneration in this mode should not be repeated many times, after a certain number of regeneration cycles, the particulate filter warning lamp comes on first, and then the glow plug warning lamp starts flashing. The driver is thus warned about the need to contact a service company.

TEMPERATURE SENSOR AFTER PARTICULATE FILTER

The temperature sensor installed after the particulate filter contains a PTC resistor. Based on a signal from the temperature sensor after the filter, the engine control unit regulates the dose of fuel injected into the engine cylinders during the expansion stroke when the vehicle is coasting. This dose decreases with increasing exhaust gas temperature downstream of the filter.

The signal from the temperature sensor downstream of the particulate filter is also used to protect it against excessively high exhaust gas temperatures.

After the signal from the temperature sensor in front of the filter ceases to arrive, its regeneration is carried out periodically according to the mileage or the time the vehicle has been in operation.

Since regeneration in this mode cannot ensure normal operation of the diesel particulate filter for a long time, after a certain number of regeneration cycles, the diesel particulate filter indicator lamp turns on, and then the glow plug indicator lamp begins to flash. In this way, the driver is warned about the need to contact a service company.

TEMPERATURE SENSOR BEFORE TURBOCHARGER

The signal from this sensor is used by the engine control unit when calculating the start of delivery and the dose of additionally injected fuel during regeneration of the particulate filter. Burning out of the soot accumulated in it is ensured by raising the exhaust gas temperature to the required level. In addition, according to the signal of this sensor, the turbocharger is protected from the action of too high temperatures.

If the temperature sensor fails, the turbocharger overheating protection does not work.

Therefore, regeneration of the diesel particulate filter is canceled and the driver is warned by the glow plug warning lamp to contact a workshop. This stops the exhaust gas recirculation in order to reduce the formation of soot.

OXYGEN SENSOR

In this case, an oxygen sensor with a broadband characteristic is used. It is usually installed on the exhaust manifold before the converter.

The oxygen sensor allows you to determine its concentration in the exhaust gas in a fairly wide range of measured values. On vehicles with a diesel particulate filter, the signal from this sensor sent to the engine control unit helps to improve the accuracy of determining the additional dose.

fuel and the moment of its supply during filter regeneration. The highest efficiency of the regeneration process is achieved at a certain minimum oxygen concentration in the exhaust gas and at a sufficiently high temperature. In this case, the regulation is carried out according to the signal from the oxygen sensor, which is supplemented by the signal from the temperature sensor upstream of the turbocharger. In the absence of a sensor signal, the regeneration parameters are determined less accurately, but it is carried out quite reliably. If the oxygen sensor fails, an increased emission of nitrogen oxides may occur.

AIRFLOW METER

A hot-film type air mass meter is installed on the inlet pipeline. According to its signal, the engine control unit accurately determines mass flow air entering the engine cylinders.

In the diesel particulate filter regeneration control system, the signal from the air mass meter is used to calculate the exhaust gas volume flow and then determine the amount of soot in the filter. The signal from the air mass meter is used to determine the degree of filling of the filter with soot only in conjunction with the signals of the temperature sensors before and after the filter, as well as with the signal of the pressure sensor.

In the absence of a signal from the air flow meter, the particulate filter is first regenerated periodically according to the mileage or the time the vehicle has been used.

Since regeneration in this mode cannot ensure normal operation of the diesel particulate filter for a long time, after a certain number of regeneration cycles, the diesel particulate filter indicator lamp turns on, and then the glow plug indicator lamp begins to flash. The driver is thus warned about the need to contact a service company.

PARTICULATE FILTER CONTROL LAMP

The diesel particulate filter indicator lamp is located in the instrument cluster. It lights up if filter regeneration is not possible, for example due to long-term operation vehicle in short distance driving mode. If the vehicle is used for a long time in short-distance driving mode, regeneration of the particulate filter may not be possible due to too low exhaust gas temperatures. In such cases, the filter may be damaged or blocked with soot. To warn the driver of the possibility of undesirable consequences, a diesel particulate filter warning lamp is provided on the instrument cluster, which lights up when a certain amount of soot accumulates in it.

If this lamp comes on, the driver is advised to drive for approximately 15 minutes at a speed as uniform as possible, which should exceed 60 km/h. The filter is most effectively regenerated when the car is moving in 4th or 5th gear and the engine is running at a speed of about 2000 rpm. At the end of the regeneration, the control lamp should go out.

If, despite taking measures to burn off soot, the warning lamp does not go out, the glow plug warning lamp lights up and the warning "Engine fault, service" is displayed on the display of the instrument cluster. After that, the driver must contact the nearest service company.

OPERATING THE VEHICLE WITH SHORT MILEAGES

In order to start the particulate filter regeneration process, the engine management system raises the exhaust gas temperature.

However, during long-term operation of a car with short runs, it is not always possible to increase this temperature to the level necessary for filter regeneration. During the subsequent regeneration of an overfilled filter, it may be damaged due to overheating as a result of the combustion of an increased amount of soot.

It is also possible to block the filter when switching to modes with increased loads. In the latter case, the engine may stall.

To prevent undesirable consequences of a failed filter regeneration, the control system turns on the particulate filter warning lamp at a certain level of filling or after several failed starts of the regeneration mode. The driver is thus warned of the need to regenerate the filter as soon as possible. He can do this by increasing the vehicle speed to values ​​at which the exhaust gas temperature rises to the level required for regeneration.

FUEL REQUIREMENTS

It is necessary to pay attention to the compliance of the fuel with the DIN standard specified in the Vehicle Owner's Manual.

The use of biodiesel fuel is not allowed. With late injection of this fuel, its unburned part may get on the cylinder walls. The moving pistons dump this fuel into the crankcase, where it enters the oil. The fuel that meets the standards evaporates during normal engine operation and is thus removed from the oil. Biodiesel fuel does not evaporate completely, as its boiling point is higher than that of conventional fuel. Fuel-thinned oil can cause damage to engine parts.

If the fuel contains a lot of sulfur, the filter quickly fills with soot, and the frequency of its regeneration cycles increases, which leads to increased consumption fuel.

Sergey Uktusov

Magazine Automaster (a— master. com. ua) No. 9-2012 and 11-2012

Like gasoline engines, diesel engines are equipped with an exhaust gas filter. But, since the principle of fuel ignition for engines of these two types differs, the exhaust gas filters for a diesel and gasoline engine differ significantly from each other.

It is worth noting that if exhaust gas catalytic converters have been installed in the exhaust system of gasoline engines for a long time, then particulate filters began to be installed without fail on diesel engines much later - after the introduction of Euro-5 environmental standards.

From the very name of the device, it is clear that its main task is to filter the engine exhaust from the contained soot particles. The particulate filter of a modern diesel engine retains up to 90% of the amount of soot contained in the exhaust. Externally, the particulate filter is a small metal cylinder filled with a special heat-resistant ceramic material. Due to the cellular structure of the ceramic filler, the filter retains the smallest particles resulting from combustion. In fact, the particulate filter is a part of the muffler designed to clean the exhaust.

The principle of operation of the particulate filter

The work of particulate filters is usually divided into two stages: direct filtration of exhaust gases (soot capture) and filter regeneration. At the stage of soot capture inside the filter, unlike the catalytic converter of a gasoline engine, no complex chemical or physical processes occur. The special fine-mesh ceramic structure of the inner part of the filter sifts exhaust gases, retaining soot particles on its walls. At the same time, even the most efficient filters are not able to completely eliminate the ingress of soot into the atmosphere, passing microparticles ranging in size from 0.1 to 0.5 microns. However, the content of particles of this size in the exhaust diesel engine does not exceed 5-10%.

Naturally, over time, the amount of soot trapped in the filter reaches a critical level - the filter becomes more and more clogged, and after a certain point this begins to affect the performance of the power unit as a whole: engine power drops, fuel consumption increases. The second stage of operation of the device is aimed at cleaning or regenerating the particulate filter. Unlike the filtration process, the filter regeneration step is a very complex process. The regeneration of particulate filters is implemented by different automakers in different ways. True, the essence of all these solutions is the same - cleaning the filter cells from clogged soot.

In most cases, the particulate filter is a combined device that combines an anti-particulate filter element and a catalytic converter for harmful exhaust gases. A typical example is particulate filters used on their cars. by Volkswagen. Thus, the developers not only implement the requirements for exhaust cleaning, but also provide a process for cleaning the particulate filter element. The device of the combined filter is as follows: inside the filter housing there are heat-resistant cells made of silicon carbide with channels of a minimum cross section. These cells are a filter element that fights soot. The inner sidewalls of the filter housing are made of a special catalytic material (usually titanium), which contributes to the oxidation and combustion of carbon monoxide and carbon dioxide. An additional function of the converter in this case is its ability to heat the particulate filter to a temperature of about 500 ° C. As a rule, this temperature is quite enough for the accumulated soot particles to simply burn out by themselves, thereby cleaning the filter cells. This process is commonly referred to as passive particulate filter regeneration.

However, the efficiency of passive regeneration of the diesel particulate filter is achieved only when the engine is running for a relatively long time under load, for example, on a long trip along a country road at high speeds. After all, only then a high temperature is reached in the filter, sufficient to burn out the accumulated soot. If the soot filling has reached a critical level, and it is not possible to warm up the filter due to insufficient engine load (driving short distances or infrequent movement around the city), but at the same time the sensors detect filter clogging in excess of the permissible norm, the process of active cleaning of the particulate filter starts. This process involves the supply of an additional portion of fuel into the engine cylinders after the main part of diesel fuel. Then the EGR valve is closed, and if necessary, the electronics temporarily changes the algorithm for the standard control of the turbine geometry. not burnt out fuel mixture enters the catalyst through the intake manifold, after which the mixture is burned, which significantly increases the temperature of the exhaust gases. Exhaust gases entering the particulate filter reach 500-700 ° C and instantly burn out soot from clogged filter cells.

An obvious indication of the start of the process of active filter regeneration will be unexpected short-term emissions of black smoke. At the same time, the instruments will show an instant and short increase in engine speed at idle with a simultaneous surge in fuel consumption. It is worth noting that the entire forced cleaning procedure is fully automated and does not require the intervention of the machine owner. The electronics reads data from the sensors installed before and after the filter, when the desired pressure level is restored, the active regeneration process ends, and the engine returns to normal mode.

Some manufacturers that do not use combined diesel exhaust aftertreatment devices use filters with a separate catalyst. Here, the filter is cleaned by automatically injecting a special additive into the fuel. When the particulate filter is filled and the engine power drops, the injection system pumps the additive into the fuel. After combustion of such a mixture in the exhaust system, an extremely high temperature exceeding 600 ° C is reached. In addition, the active substance of the additive does not decompose when burned with diesel fuel, but enters a hot particulate filter, where, when burned, it raises the temperature to 900 ° C, providing instant burning of soot and quick cleaning of the filter. Given the short duration of exposure to ultra-high temperatures and the strength of the materials from which the filters are made, the exhaust system is not destroyed.

Removing the particulate filter - methods and consequences

Unfortunately, frequent regeneration negatively affects the engine of the machine. During regeneration, the rich fuel mixture does not burn completely and enters the engine oil. As a result, the oil liquefies, increasing in volume. The protective and lubricating properties of the oil are reduced, in addition, liquid oil easily overcomes seals, causing a risk of getting into the intercooler and cylinders.

The service life of particulate filters reaches 110-120 thousand kilometers of the car. However, given the low quality of domestic diesel fuel, it is not uncommon for a filter to be replaced on a new car after 25-30 thousand kilometers. Depending on the model of the car, the cost of a filter for the exhaust system of a diesel engine ranges from 900 to 3000 euros.

An effective alternative to replacing the particulate filter is to remove it. By removing the filter, the owner of the machine will save himself from the problems associated with regular blockages and the need to clean the device. Traction characteristics of such a car increase noticeably, and fuel consumption decreases. In addition, there is no need for special engine oils required for vehicles with diesel particulate filters. With regard to possible negative consequences If the filter is removed, then with the correct dismantling of the device, in addition to an increase in harmful emissions of fuel combustion products to the level of the Euro-3 requirement, nothing bad will happen to the car.

Today, many car services offer a diesel particulate filter removal service. However, trusting "garage" specialists is quite dangerous. This option is fraught with damage to the sensors of the exhaust system, which leads to the activation of the emergency operation of the car and subsequent repairs. To properly remove the particulate filter, several steps must be taken, including preliminary computer diagnostics, ECU reprogramming and subsequent technical dismantling of the device.