The principle of operation of the fuel vapor absorber. Adsorber

In almost every modern car, which meets the stringent environmental requirements of at least Euro-3, there is such a unit little known to ordinary motorists as an adsorber. It makes the car much friendlier to the environment, besides, without it, most cars simply cannot work. What is an adsorber, what are its functions, what are the design features of this element? You will find answers to all these questions in our material.

What does an adsorber look like?

The process of adsorption is the absorption of gaseous media by bodies of solid or liquid consistency. Accordingly, the main task of the adsorber is to absorb gases, preventing them from entering the environment. However, these are not exhaust gases, but gasoline vapors emanating from the cavity of the fuel tank. When the car engine is running, the trapped vapors are transferred to the intake manifold, during parking, gasoline vapors are neutralized inside the adsorber.

Thus, the adsorber does not allow gasoline vapors to penetrate into the environment, which is required by the norms of modern environmental standards, and also does not let them into the passenger compartment. In addition, the delay, condensation of vapors and the return of gasoline back to the fuel system provide additional savings.

It should also be noted such a function performed by the adsorber as complex ventilation of the fuel tank. When fuel is consumed, the vacated space is filled with air, which is supplied precisely through the adsorber. Here the air is filtered and dried, which has a positive effect on the operation of the engine as a whole.

The key basis for dividing adsorbers into separate classes is its content. The following options are currently in use:

• granular adsorbent, which is in a stationary state;
• granular adsorbent capable of moving in the cavity of the device;
• fine-grained filling with a fluidized bottom layer.

Adsorbers with static coarse-grained filling show maximum efficiency. Its main advantage is protection from partial or complete loss active substance along with fuel vapors.

How does a gasoline vapor adsorber work?

In the diagram: 1 - steam pipe; 2 - adsorber tube and purge valve; 3 - shalngs; 4 - purge valve; 5 - fuel drain pipe; 6 - fuel vapor separator; 7 - gravity valve; 8-10 - steam pipes; 11 - adsorber;

Structurally, the adsorber is a hollow cylinder filled with a filtering agent and equipped with a number of additional modules. Its main elements:

• directly container for the filter;
• activated carbon in the form of granules - this substance effectively retains gasoline vapors;
• separator - responsible for returning trapped vapors to the fuel tank;
• gravity valve - necessary in emergency situations, in particular, in case of accidents, when there is a high risk of gasoline overflowing through the gas tank neck;
• solenoid valve - responsible for switching the operating modes of the adsorber;
• connecting tubes - combine all the elements of the unit into a single system.

The key element of the system, in addition to the filter tank itself, is the solenoid valve. It provides not only switching the accumulation mode to the mode of transferring the accumulated vapors to the fuel system, but is also responsible for the ventilation of the entire system. Thanks to this part, the retained fuel moves, the adsorber cavity is released for a new cycle of operation, and the system as a whole is maintained.

How the adsorber and valve work

Contents of the adsorber

The scheme of operation of a car adsorber is quite simple, but there are some nuances in it that every motorist is recommended to know. Therefore, we will dwell on this issue in more detail.

Gasoline vapors, being lighter than air, rise to the top of the gas tank. Here they are detained by a separator combined with a gravity sensor. Here, a certain part of the vapors condenses and flows back into the tank in a liquid state.

However, a certain proportion of gasoline vapors is able to pass through the gravity valve and separator, and as a result enters the adsorber. Here it is retained by a carbon filter, condenses in the gaps between large coal granules and is stored until the engine is started.

If the engine is started, the solenoid valve opens and passes the gasoline accumulated in the adsorber cavity into the intake manifold line or into the throttle system. Mixing with the air flowing through throttle valve, gasoline vapors in the form of a ready-made fuel-air mixture are fed into the cylinders.

As can be seen, the principle of operation of the adsorber is quite simple and understandable, however, the efficiency of its operation in different cars can be different - this is largely due to the use of adsorbing modules of various types.

Symptoms of a malfunction of the adsorber and valve

As a result of long-term operation, mechanical damage, exposure to high voltage current or aggressive environments, the adsorber design may be damaged. The most common causes of failure are:

• Loss of tightness of the solenoid valve and simultaneous clogging of the channel that transfers the accumulated gasoline to the engine. In this case, evaporation freely enters the intake manifold, often clogging it. Signs of such a malfunction - the engine does not start on the first try or when the gas tank is incomplete.
• Clogging of the connecting pipes without the solenoid valve losing its tightness. In this situation, the fuel vapors will condense directly in the gas tank, gradually increasing its internal pressure. If a hiss is heard when the gas tank cap is unscrewed, then this most likely indicates clogged adsorber tubes.

How to identify malfunctions of the adsorber valve

The valve, as the most sensitive element in the design of the adsorber, fails especially often. The following “symptoms” will indicate problems with the valve.

After cars appeared that meet the Euro-3 environmental safety standard, auto designers were puzzled by the creation of a device capable of retaining hydrocarbon vapors in order to exclude their emissions into the atmosphere. Therefore, in the fuel system of most cars, and domestic cars, including VAZ, were no exception, a part appeared - an adsorber. What is it? I propose to consider this detail from all possible angles using an example domestic car VAZ 2114.

1 Adsorber - what is it?

If we make a literal translation of the word adsorber with in English, then in the end we will get two meanings similar in meaning - "absorb", "amortize". What is the need for it anyway? Adsorption is a process in which gases are absorbed by both solids and liquids. In this case, the main element that absorbs spent fuel vapors is activated carbon. It is with them that they fill part of the free space of the adsorber.

The composition of this part includes several structural elements:

• Adsorber
• Purge valve
• Adsorber tubes and purge valve
• gravity valve
• Front steam pipe
• vapor separator
• Fuel drain pipe
• Several hoses

2 The principle of operation of the adsorber in the VAZ 2114

The adsorber works as follows. Fuel vapors generated in fuel tank, rise up and gradually accumulate at the neck of the tank, from where they have a direct path to the separator, in which the process of condensation of these vapors takes place. Vapors that have turned into a liquid are drained back into the fuel tank. However, not all vapors have time to become liquid again. Part of the vapor that remains in the form of a gas enters the adsorber, where it is absorbed with the help of an adsorbent - activated carbon.

It is worth noting that the entire process described above proceeds exclusively with the engine turned off. Otherwise, the system will have to open . In this case, gasoline vapors that have formed in the fuel tank and have not had time to transform into a liquid will be blown out through the engine intake pipe. VAZ 2114 and be burned.

This principle of operation implies the presence of several advantages at once:

1. Prevention of atmospheric pollution by harmful fumes
2. The car absorbs less fuel while driving (although the level of economy does not even reach 1 percent, but at the same time the fact is a stubborn thing - without burning gasoline vapors, the engine would need more fuel).

3 Signs by which you can determine that the adsorber is faulty

Even such a detail as an absorber can become clogged and become unusable. The causes of a malfunction can be different (mechanical damage, natural wear of the absorbing element). The main symptom of a malfunction of the adsorber is the presence of excess pressure in the fuel tank. The reason for this is the accumulation of an excessive amount of fuel vapors, which can neither turn into a liquid state nor be removed through the adsorber. It is quite simple to make sure that there is excess pressure of fuel vapors in the fuel tank - you just need to unscrew the fuel tank cap and listen for hissing when the cap is opened. If there is a hiss, then it is time to change the adsorber, since an excess amount of harmful vapors accumulates in the fuel tank.

There is another way to determine the malfunction in cars VAZ. After warming up the engine above a temperature of 60 ° C, a significant drop in engine speed at idle begins. In addition, your car may suddenly stall while driving for no specific reason.

If something similar happened with your car, then we advise you to check the health of the adsorber. This can be done as follows - disconnect the hose going to the manifold from the valve and plug it for two to three days. If the symptoms that bother you have not disappeared, and your favorite VAZ is still “playing” with speed as it pleases, then most likely there is only one verdict - adsorber blockage.

Undoubtedly, the car, as it drove, will continue to travel more than one kilometer even with a faulty adsorber, but at the same time, its idling will float like a sinusoid. However, we note that an adsorber malfunction that has not been eliminated in time, or at least excess fuel vapors not released from the fuel tank in time, threatens to “shoot” the fuel tank cap from the neck, or maybe you just won’t be able to open it. Therefore, it is easier to replace a defective part than to constantly be afraid of an unauthorized "shot", since no one can predict where a flying fuel tank cap will fall.

4 Canister replacement

Replacement of this part in VAZ 2114 can be carried out at the nearest station to you Maintenance, but you can do it yourself. Since you will spend no more than 20 minutes on everything about everything, you can also replace the adsorber yourself.

So let's get started. First you need to dismantle the part to be replaced. First, we release the adsorber from the existing fasteners, then disconnect the hose that supplies fuel vapor to the throttle, and only after that the wires and block. The next step is to disconnect the purge valve and fuel outlet hose from the separator. And finally, we unscrew and remove the bracket (it won't take much time, since it is fastened with only three bolts).

After the successful dismantling of the spent adsorber, we proceed to install the purchased part. The longest piece of rubber hose available is attached to a tube through which fuel vapor is supplied to the purge channel. We attach a smaller part of the hose to the intake tube from the separator. Now, using the bracket, we install the adsorber in its rightful place. Next, the vapor supply hose is connected to the purge channel. The purge channel, in turn, is mounted on the engine cover. It is also necessary to connect the block with wires. A rubber tube is installed between the adsorber and the purge channel. Important: the tube must be resistant to gasoline and engine oil. The adsorber has been installed. Everything was done quickly, efficiently and without the involvement of third-party specialists.

5 Diagnosis of the adsorber purge valve on its own

If it is necessary to replace only the adsorber valve, then it makes no sense to go to the nearest service station. It will take you no more than 5 minutes of your time, provided you have a Phillips screwdriver. You can find such a valve in almost any auto parts store that sells spare parts for VAZ. It costs, by the way, it is inexpensive - no more than 700 rubles. Together with the valve, it is recommended to replace the adsorber sensor, since it controls the valve directly. However, it is worth changing it, provided that the sensor emits extraneous noises resembling crackling. Moreover, sometimes difficulties arise at the moment when it is necessary to purchase an adsorber sensor, since it is not sold everywhere.

First you need to diagnose the adsorber valve to the question of serviceability. To do this, we need a multimeter and a pair of wires. Before checking, it is necessary to release the retainer and remove the wiring harness block from the purge valve. Then we connect the "minus" of the multimeter to the "mass". We turn on the ignition, we measure the voltage at terminal "A" of the wire block. The multimeter reading should not be less than 12 volts. If the multimeter display shows less than 12 volts or there is no voltage at all, then you most likely have a dead battery or a faulty computer.

Using a Phillips screwdriver, loosen the clamp that secures the tube to the valve. We remove the hose from the nozzle. Using a screwdriver, remove the valve from the adsorber. Next, it is necessary to apply a voltage of 12 volts from the battery to the terminals ("+" - terminal "A", "-" - terminal "B"). After applying voltage, the valve should open with a characteristic click. If this does not happen, then the valve must be replaced.

6 Replacing the adsorber purge valve in the VAZ 2114

So, let's start replacing the adsorber valve in the VAZ 2114. To begin with, we de-energize the car by removing the negative terminal from battery. Then the plug is disconnected from the CPA. To get to the valve, we need to loosen the clamp of the inlet pipe a little, then remove it from the mass air flow sensor and take it aside. Next, slightly bend the valve mount to make unhindered dismantling. It is necessary to take the mount to the side at a distance not exceeding 1 centimeter.

After all the operations done, pull the valve up the grooves. On this, the dismantling of the adsorber valve is not yet completed. It remains to disconnect the inlet fitting. The whole problem is that one of them disconnects very simply, but with the second, as a rule, difficulties arise. The snag is that the inlet fitting is fixed by a special latch. To dismantle it, you need to pry off the plastic antennae, and for this you need to drown the latch (in this case, the fitting should be raised slightly up). Dismantling is completed, installation is carried out in the reverse order.

7 Conclusion

So, let's sum up a little. We managed to find out why an adsorber is needed at all in the VAZ 2114 and how it can be replaced without resorting to the help of specialists. This detail is very important for vehicles that meet Euro 3 environmental standards. If the adsorber is removed from the VAZ 2114 car, then the level of environmental friendliness of your car will drop to "Euro 2" or "Euro 1".

According to the requirements of new environmental standards that limit the content of harmful substances in exhaust gases, vehicles must be equipped with an EVAP system. This equipment prevents harmful fuel fumes from entering the atmosphere. The adsorber performs the main function in the fuel vapor recovery system. Some underestimate the importance of this element in the operation of the car. However, a malfunction of this, at first glance, a minor node can damage the fuel pump and affect the operation of the entire engine. Therefore, experts recommend checking the adsorber valve when there are signs of a motor malfunction.

Absorber valve diagram

The EVAP system is installed on gasoline engines internal combustion to prevent fuel vapors from escaping into the atmosphere. The canister purge solenoid valve is an element of this system. Therefore, in order to figure out what an adsorber valve is for and how it works, it is important to understand how the entire system works.
The design of the adsorber is a container filled with an adsorbent, most often activated carbon. The device is connected to the fuel tank and control valve of the car with special tubes.

The canister valve is installed between the intake manifold and the canister and performs the function of ventilation.

Gasoline vapors formed in the fuel tank enter the separator, where they condense and drain back into the tank. Some of the vapor does not have time to condense in the separator and enters the adsorber through the steam line. In the filter system, they are absorbed by activated carbon, accumulated and then fed into the intake manifold when the engine is started.
The process of absorption of fuel vapors takes place only when the engine is turned off. When the car is running, the electronic control unit opens the canister purge solenoid valve, through which air enters and thus ventilation occurs. At the same time, the accumulated condensate, together with air, is sucked out of the adsorber and again enters the engine, where it is afterburned. The canister valve ventilates the entire mechanism and directs fuel condensate back to the engine.

Adsorber valve malfunctions and their elimination

The almost continuous operation of the adsorber of the fuel vapor absorption system can cause damage to the purge valve.
A malfunctioning adsorber valve often leads to damage to the fuel pump. Due to poor ventilation of the canister, gasoline accumulates in the intake manifold, the engine loses power, and fuel consumption gradually increases. This can lead to a complete stop of the engine. The operation of the entire car depends on how the adsorber valve works.

How to check the operation of the canister purge valve?

Checking the absorber valve

In order to notice and correct problems in time, it is necessary to regularly check the adsorber valve. In this case, it is possible to identify a breakdown by certain indirect signs.
When the engine is running at idle or cold weather the vapor absorption system makes characteristic sounds, so the adsorber valve clicks. Some confuse this sound with malfunctions of the timing, rollers or other parts. You can check this by sharply pressing the gas pedal. If the sound has not changed, then it is the adsorber valve that is clicking. Experts can explain what to do if the adsorber valve knocks too hard. To do this, it is necessary to tighten the adjusting screw, while first it is cleaned of epoxy.

The absorber valve can be adjusted.

The screw turns about half a turn. If it is tightened too much, the controller will give an error. Such an adjustment of the adsorber valve will make it work softer and quieter.
However, how to check the adsorber valve for damage?
A broken valve can be determined using the error diagnostic system or a mechanical check.
Electronic error codes are stored in the controller's memory and indicate electrical damage. To check the valve, it is recommended to pay attention to errors generated by the controller, such as "break in the control circuit of the adsorber purge valve."
Signs by which it is possible to mechanically determine the malfunction of the adsorber valve:

1. The appearance of failures at idle speed of the engine.
2. Very low engine thrust.
3. There is no sound of valve operation when the engine is running.
4. A hissing sound when the gas tank cap is opened indicates a vacuum in the system. This is a sure sign of a malfunctioning adsorber ventilation.
5. The appearance of the smell of fuel in the car. However, there may be other reasons for its appearance.

Do-it-yourself absorber valve replacement

Absorber valve

If signs of malfunction are found, repair or replacement of the valve is required. The canister valve is inexpensive and easy to replace. For dismantling, you need to have a pair of Phillips screwdrivers and know where the canister purge valve is located.
Operating procedure:

Markings of the old and new valve must match.

1. Open the hood and find a cylindrical device - an adsorber.
2. Remove the negative terminal from the battery.
3. Disconnect the wiring harness by pressing the latch and pulling towards you.
4. Loosen the valve mount.
5. Remove the fittings under the latch and disconnect the hoses.
6. Remove the valve together with the bracket from the adsorber.
7. The new valve is installed in the reverse order.

Thus, even such a small element as an adsorber valve performs important functions and its malfunction can seriously disrupt the operation of the entire engine. Therefore, it is important to monitor the condition of your car and carry out diagnostics in time.

Recently, more and more new devices have appeared in cars, and the absorber is one of them. To comply with the Euro-3 environmental standard, all vehicles are required to have equipment that prevents the entry into the atmosphere of hazardous substances that are formed as a result of fuel combustion.

The absorber is of the greatest importance in capturing and processing waste vapors in the machine. Its device and the basic principles of operation should be known to every car owner.

Types of used absorbers

The topic of environmental protection is relevant for our country. Everyone should do it, especially owners of cars with internal combustion engines. Tons of harmful substances emitted annually into the atmosphere do not make the world around cleaner and better.

To improve the environmental situation for each vehicle an EVAP system is installed, in which the central place is given to the absorber. Classification depending on the type of absorbent component.

1. Fixed granular absorbent is used;

2. Mobile granular absorbent is used;

3. A fine-grained absorbent is used, with a constantly boiling bottom layer.

Most automakers use devices that have the first type of design, since it has been proven to be the most effective. Designs of the second and third types also trap spent fuel vapors.

Their main disadvantage is the possibility of absorbent particles entering the atmosphere with spent fuel vapors. Therefore, in order to maintain an effective working condition, the volume of absorbent in the models with mobile and boiling states needs to be checked regularly. To do this, the absorber must be dismantled.

The device of the absorbent element of the car

Externally, the absorber looks like an oblong metal can with two tubes. Through the first, the vapors to be processed are fed in, and condensate is discharged through the second. Inside the main body, which has a cylindrical shape and is divided inside by a steel separator into two unequal parts, an absorbent and an evaporator are placed.

The separator covers ¾ of the inner diameter, which makes it possible for the coolant to flow freely through the cylinder. The absorber consists of a generator and a condenser. To exclude their contact, they are separated by an inclined plate. The separator has one half - solid, the second - perforated.

This design allows the absorbent to be condensed and returned if it evaporates. This allows you to maintain the volume of the absorbent. Settling drops of refrigerant, support it stable pressure. Subsequently, they burn out in the motor.

Functioning principles of absorbers

Now let's look at how the absorber works on a car. The absorber is located above, the evaporator below it. Due to the passage of the refrigerant through the tubes, the condensed liquid flows down. Having worked out the cooler enters the evaporator tubes. Mixed with the absorbent solution, it enters the heat generator.

When heated, the refrigerant separates. In the condenser, water and saturated absorbent are separated from the steam. The separated vapors enter the fuel tank.

Due to the location of the absorber before the catalyst, the fuel vapors collected by it bypass the exhaust manifold and the catalyst. Due to this, the catalyst keeps working longer. When the solenoid valve is opened in the absorber, it is purged with air. The vapors accumulated in it enter the engine for recycling.

Characteristics of the working absorber

Consider some characteristics that allow us to judge the performance of the absorber.

When not in use, the pressure inside the housing must equalize with atmospheric pressure.

To prevent entrainment of the absorbent during the passage of the refrigerant, the absorbent liquid must have a stable consistency.

To be able to control the flow of the refrigerant, it must have a constant temperature.

Both liquids must be mutually soluble.

A prerequisite is high-quality mixture formation between the evaporator and the refrigerant.

Both fluids used must be chemically stable and completely safe.

Used absorbents and coolants

In modern technology, absorbers use two options for combining evaporators and absorbents. Firstly, ammonia can be used as a coolant, water acts as an absorbent. The second mixture uses water and lithium bromide. Both mixtures have approximately the same performance.

Activated carbon is often used as a dry absorbent. The choice is left to the automaker.

Thus, the absorber significantly reduces the emission of harmful substances into the atmosphere and allows you to slightly save fuel.

When gasoline comes into contact with air, vapors are released, which, when released into the atmosphere, worsen the environment. To capture them, an adsorber is installed in the ventilation system. In a number of European countries, the use of this device in a car is mandatory at the legislative level and is determined by the action of environmental standards Euro-2 and higher. Knowing the adsorber device and why it is needed, you can easily identify malfunctions, as well as better understand its advantages.

What is an adsorber and EVAP system

Many motorists call a device for absorbing fuel vapors an "absorber", but this is wrong, since the name "adsorber" comes from the Latin words "ad" (in the lane - "on") and "sorbeo" (in the lane - "I absorb") , which together means "surface absorption" (accumulation on the surface). In turn, the absorber absorbs the entire volume and cannot be used in this case.

Evaporative Emission System Schematic

Since the largest amount of vapor accumulates in the fuel tank, the adsorber is located not far from it. In fact, it is part of an entire EVAP system. The latter consists of the following elements:

• Gasoline vapor separator.
• The adsorbent element is a container with an adsorbent substance.
• Vent valve.
• Canister purge solenoid valve (located between the canister and intake manifold).
• Pipelines and hoses for connection to the fuel tank, intake manifold and atmosphere.

In addition to the main elements, the EVAP system is part of the OBD-II on-board diagnostic system and includes a number of sensors (fuel vapor, pressure) and an electronic control unit (ECU) that actuates a solenoid valve.

Types and principle of operation of the adsorber

Depending on the substance used, several types of adsorbers are distinguished:

• with a fixed granular adsorbent medium fractions;
• with a mobile granular adsorbent of medium fractions;
• with a fine-grained adsorbent in which the lower layer is in a state of boiling.

The most popular is the first type of systems in which activated carbon is used as an absorbing component.
The adsorber has three exits for connection of pipelines. The first one is for gasoline vapors, the second one is connected to the solenoid valve, and the third one is connected to the air filter, which provides the pressure drop necessary for purging.

How EVAP works:

1. The vehicle is at rest, the engine is off.
2. In the fuel tank, gasoline vapors are naturally released, which rise to the top and accumulate at the neck.
3. In this zone of the tank there is a separator that separates the liquid component, which settles in the form of condensate and is discharged back into the gas tank with special tubes.
4. The rest of the vapors, which have not settled in the form of condensate, pass through the steam line, falling into the adsorbing element. They gradually accumulate on the surface of the adsorbent.
5. The driver starts the engine and when the set crankshaft speed is reached, the canister purge solenoid valve starts working. When the car is idling, the valve does not work.
6. Through the vent valve, air enters the adsorption element due to the pressure difference (between the intake manifold and the atmosphere), and purge is performed.
7. Air and gasoline vapors from the adsorber are fed into the combustion chamber of the engine.

Symptoms of an adsorber malfunction

The main malfunction of the adsorber is the contamination of the absorbing element, which occurs naturally. In this case, the pressure in the tank will increase, since the vapors will not be removed. characteristic feature this will hiss when you open the gas tank cap. The drop in engine speed, which is noted by many motorists, can also be the cause of clogging of the adsorber.

Another important malfunction may be a violation of the tightness of the solenoid valve. In this case, the adsorber sensor may give an error " check engine through the diagnostic system. A sign of a violation of the tightness of the solenoid valve is the difficulty of starting the engine the first time, as well as with an incomplete fuel tank. You can fix such a breakdown in the service center.