The internal combustion engine (ICE) of each vehicle is subjected to significant loads during operation. To ensure its correct operation and the safety of individual mechanisms and their parts, sufficient cooling of the motor is an important point.

There are two main types of internal combustion engine cooling systems: air and liquid. The air type in modern automobile construction is used only in sports cars, as an addition to the liquid one, since the benefit from the air flow alone to ensure the normal operating temperature of the unit is negligible.

The first vehicles of the automobile manufacturer ZAZ were equipped exclusively with air cooling. Despite various engineering ideas, the Zaporozhtsev engines often overheated on hot summer days.

The general picture of the cooling system

Regardless of what type of engine is installed in the car and what brand of car, the cooling system has a generally similar structure. Ensuring the normal operating temperature of the power unit is achieved by circulating the coolant through the channels of the system. Thus, each ICE unit is cooled equally regardless of the temperature load.

The hydraulic cooling system can also be of several varieties:

Thermosiphon- circulation is carried out due to the difference in density between hot and cold liquid. Thus, the cooled antifreeze displaces hot liquid from the power unit, sending it to the radiator channels.
Forced- the circulation of the coolant is due to the pump.
Combined- heat removal from most of the engine is forced, and individual sections are cooled by a thermosyphon method.

The coercive system is perhaps the most effective and is used in most modern passenger cars.

Main elements

The engine cooling system contains the following elements:

Cooling jacket or "water jacket". It is a system of channels passing through the cylinder block.
A cooling radiator is a device for cooling the liquid itself. Consists of bent pipe channels and metal fins for better heat dissipation. Cooling takes place both thanks to the counter air flow and the internal fan.
Fan. Cooling system element designed to enhance air flow. On modern cars, it turns on only when the temperature sensor is triggered, when the radiator is unable to fully cool the liquid with the oncoming air flow. In older car models, the fan runs continuously. Rotation is transmitted to it from the crankshaft through a belt drive.
Pump or pump. Provides circulation of coolant through the channels of the system. It is driven by a belt or gear drive from the crankshaft. As a rule, powerful engines with direct fuel injection are equipped with an additional pump.
Thermostat. The most important part of the cooling system, which controls circulation over a large cooling circle. The main task is to ensure normal temperature conditions during vehicle operation. Usually installed at the junction of the inlet pipe and the cooling jacket.
Expansion tank - a capacity necessary to collect the excess coolant that occurs during its heating.
Heating radiator or stove. In terms of its design, it is similar to a cooling radiator in a smaller size. However, it is used exclusively for heating the passenger compartment in the winter and does not play a direct role in cooling the internal combustion engine.

Circles of circulation

The cooling system in the car has two circles of circulation: large and small. It is the small one that is considered the main one, since when the unit is started, the coolant immediately begins to circulate through it. In the work of the small circle, only the channels of the cylinder block, the pump, and also the interior heating radiator are involved. The circulation runs in a small circle until the internal combustion engine reaches normal operating temperature, after which the thermostat is triggered and opens a large circle. Thanks to such a system, engine warming up is significantly reduced, and in winter, the system does not so much cool the unit as it maintains its normal temperature regime.

A fan, a cooling radiator, inlet and outlet channels, a thermostat, an expansion barrel, as well as those elements that take part in the functioning of a small circle are involved in the operation of the large circle. The outer circle, also known as a large circle, begins to work when the temperature of the coolant reaches 80-90 ° C, and provides its cooling.

How the system works

In general, the operation of the system is quite simple. A powered hydraulic pump circulates the coolant through the jacket of the cylinder block. The circulation rate depends on the number of revolutions of the engine crankshaft.

Antifreeze, passing through the channels in the cylinder block, removes excess heat from the unit and flows back into the pump intake compartment, bypassing the thermostat. When the temperature of the coolant reaches 80-90 ° C, the thermostat opens a large circle of circulation, blocking a small one. Thus, the liquid after the cylinder block is directed to the cooling radiator, where its temperature is reduced due to the oncoming air flow and the fan. Further, the process is repeated.

Possible problems and their elimination

Despite the simplicity of the design, the cooling system of the power unit is capable of malfunctioning during vehicle operation. In this regard, the engine will operate in an increased temperature regime, due to which the resource of its parts will significantly decrease. The reasons for the incorrect operation of the cooling can be completely different.

Thermostat worn out

Most often, malfunctions in the system are associated precisely with the valve that switches the circulation circles, it is also a thermostat. If the part is jammed in one position or the valve does not close the channels of the circulation circles tightly, the engine may take much longer to warm up, or vice versa, the unit will begin to overheat strongly without sufficient cooling.

How the thermostat works

As a rule, the breakdown of a thermostat is associated with a violation of its integrity. The valve is based on thermal wax, which, when heated, expands and squeezes the membrane, opening a large circulation circle. If for any reason the wax has leaked out of the part, the valve will stop functioning and the antifreeze will not be able to fully cool. Also, the cause of wear can be an untimely replacement of the coolant or its poor quality. Corrosion of the thermostat spring causes the part to jam in the open or less often closed position. In both cases, the engine will not be able to operate in the normal temperature range - the liquid will either be constantly cooled, even when there is no need for it, or, on the contrary, will be hot all the time.

Determining wear is quite simple and can be done in two ways. The easiest way to check is the non-removable method. To do this, immediately after starting the engine, touch the radiator inlet pipe. If it becomes warm almost immediately after starting the internal combustion engine, this indicates that the thermostat is stuck in the open position. Conversely, when the nozzle remains cold, even if the temperature reading is at its peak, it indicates that the thermostat is unable to open.

More precisely, you can make sure that the reason for the incorrect operation of the cooling system is precisely the malfunction of the thermostat by dismantling it. The removed valve is placed in a container with water and heated. When the water temperature reaches 90 ° C, a serviceable valve must necessarily work - the thermostat stem will move. If this does not happen, it is safe to consider the part to be faulty.

A failed thermostat cannot be repaired, but must be replaced. Its cost for most cars rarely exceeds 1000 rubles. The valve can be replaced by yourself, without visiting a car service.

Hydraulic pump problems

One of the reasons for overheating of the machine's power unit may be a malfunction of the cooling system pump. Most often, the problem is that the drive belt of the hydraulic pump is broken or its tension is too weak. In this case, the pump will stop pumping antifreeze, or it will not do it fully. It is quite simple to check this, you just have to bring in the engine and observe the behavior of the drive belt. If it works with slippage, the tension should be increased or completely replaced with a new belt. This most often solves the problem.

Situations arise when the problem lies in the pump itself: wear of the impeller, bearing, sometimes even a shaft crack is possible. Among other things, the joints of the connection of the pipes with the pump may not be tight, and the pressure created by the pump will provoke a leakage of the coolant. It is quite simple to diagnose a leak; you need to put sheets of white paper on the floor under the engine for several hours. If even small spots of blue or greenish color are visible on it, this indicates wear on the pump gaskets.

You can check the performance of the pump itself by pinching the upper radiator hose with your fingers for a few seconds while the unit is running. A working pump will create a strong pressure and after releasing the hose, you will feel that the liquid quickly ran along the line. It is also worth remembering that the increased noise of the internal combustion engine and the play of the pump pulley indicate bearing wear. Typically, its wear is associated with fluid seeping through the seal, which flushes grease from the bearing.

The coolant pump, unlike the thermostat, can be partially replaced, but often car owners prefer to fully change the mechanism.

Replacing the pump:

First of all, it is necessary to disconnect the mass of the car from the battery, and the piston of the first cylinder must be at top dead center. Dismantle the belt tension roller and remove the camshaft pulley.
Next, you should drain the coolant from the lower plug in the radiator.
Having unscrewed the pump mounting bolts, it must be disconnected from the cylinder block.
After evaluating the visually removed mechanism, it is important to determine its wear. If the impeller, oil seal and drive gear are damaged, it is better to replace the pump completely.
The new mechanism must be installed with a new gasket, since the old one can have even minor damage, which subsequently lead to a coolant leak. The pump is installed in such a way that the number indicated on the body looks up.
Further assembly is carried out in the reverse order of disassembly. It is better to fill the coolant with a new one, but you can also use the one that was, if its resource has not yet been exhausted.

Heatsink and fan problems

Insufficient engine cooling may be due to problems with the radiator and fan. First of all, it is worth remembering that a radiator that is too heavily clogged with dust and insects is unable to fully cool both with the oncoming air flow and with a fan. Often, cleaning it solves the cooling problem.

The device of the "classic" engine cooling radiator. In many modern engines, the coolant is not poured through the radiator neck, but into the expansion tank.

And yet, more serious situations are possible - radiator cracks, which can occur, both in an accident and as a result of corrosion. The radiator can be repaired in most cases. Brass and copper are repaired using soldering, and aluminum with special sealants.

Before the start of soldering, the damaged spots are thoroughly cleaned with an emery cloth until a metallic sheen appears. After that, the crack is processed with a soldering flux and a uniform layer of solder is applied using a powerful soldering iron (see video).

The aluminum radiator cannot be soldered, however, special sealants are offered for their repair, or you can use conventional "cold welding". Before starting to repair cracks, it is important to clean the defective areas well. The adhesive mass is kneaded well until smooth and applied to the problem area. It is worth remembering that you can only operate the car the next day after the repair - the epoxy glue dries for a long time.

As for the cooling fan, its failure may be associated with a break in the electrical wiring or a violation of the drive from the crankshaft, if rotation is transmitted from the power unit.

In the first case, it is worth visually assessing the condition of the wires going to the fan motor; if a break is detected, the damaged contacts must be reconnected. If the condition of the wires is normal, and the fan still does not work, it is possible that the engine itself or the sensor responsible for its timely activation may have broken down. In this case, it is better to contact a car service, where they will determine the reason why the fan does not turn on. In case of problems with the sensor, the airflow can either continuously or not turn on at all.

In cars where the fan starts to rotate when torque is transmitted from the engine, the breakdown is most often associated with a break in the drive belt. Replacing it is quite simple: you need to loosen the pulley tension and install a new belt.

More details about the design and repair of the cooling fan.

Flushing the cooling system and changing the fluid

The hydraulic cooling system requires timely flushing of the lines, otherwise corrosion, salt deposits, and other contaminants may form on the walls of the channels.

Clogging reasons

The main reason for system contamination is the use of ordinary water as a coolant. Running water from the tap contains a large amount of salts, creates scale and rust on the walls of the mains. The use of distilled water is less harmful, but it is not able to provide adequate cooling during the hot period. In addition, in winter at a subzero rate, the water will freeze and expanding can violate the integrity of individual parts and connections.

The use of high-quality antifreeze or antifreeze is more advisable. Special cooling agents have a long service life and do not freeze even at very low temperatures. However, the additives contained in the composition, over time, begin to precipitate, clogging the system.

Flushing process

First of all, before flushing, all the coolant is drained through the outlet plug on the radiator, located at the very bottom, and on the cylinder block to remove residues.

It is important to remember that the fluid must be drained only on a cold engine!

After draining, the plugs are re-tightened and water with citric acid or, better, a special cleaning liquid, is poured into the expansion tank.

Next, the engine starts and idles for 15 minutes. In this case, make sure that a large circulation circle is opened. Also, when flushing, do not forget that the salon stove must operate in the maximum heating mode. When the unit has cooled down, the liquid can be drained by opening the radiator and cylinder block plugs. It is recommended to repeat this process until, when draining, a clear liquid flows out without visible contamination.

Filling with new coolant can be carried out immediately after the end of flushing. Pour antifreeze or antifreeze into the expansion barrel carefully and slowly to avoid the formation of air pockets in the system.

When the tank is almost completely filled, you need to close it and start the internal combustion engine for a few minutes so that the liquid evenly spreads through the system. Further, after turning off the unit, antifreeze or antifreeze is topped up to a level between the maximum and minimum marks on the barrel.

In conclusion, it should be said that there is no fundamental difference in the use of antifreeze or antifreeze. However, in many countries of the world, car manufacturers have long stopped using antifreeze, since its effectiveness is somewhat lower. Modern antifreeze is manufactured using the latest technologies and to a greater extent protects the engine from overheating, and the cooling system lines from pollution.

Reliable and trouble-free operation of the internal combustion engine (internal combustion engine) cannot be carried out without a cooling system. Its basic principles of operation are conveniently presented in the form of a diagram of an engine cooling system. The main purpose of the system is to remove excess heat from the engine and. An additional function is the heating of the car with the interior heater stove. The device and principle of operation, shown in the diagram, are approximately the same for different types of cars.

Scheme, elements of the cooling system and their work

The main elements that make up the engine cooling system circuit are found and are similar in different types of engines: injection, diesel and carburetor.

General diagram of the liquid engine cooling system

Liquid cooling of the motor makes it possible to equally take heat from all units and parts of the engine, regardless of the degree of thermal load. A water-cooled engine produces less noise than an air-cooled engine and has a faster warm-up rate when starting.

The engine cooling system contains the following parts and elements:

cooling jacket (water jacket);
radiator;
fan;
liquid pump (pump);
expansion tank;
connecting pipes and drain taps;
interior heater.

The cooling jacket ("water jacket") is considered to be the cavities communicating between the double walls in those places where the removal of excess heat is most needed.
Radiator. Designed to dissipate heat into the surrounding atmosphere. It structurally consists of many curved tubes with additional ribs to increase heat transfer.
The fan, which is switched on by an electromagnetic, less often a hydraulic clutch, when the coolant temperature sensor is triggered, increases the air flow on the car. Fans with a “classic” (always on) belt drive are rare these days, mostly on older cars.
A centrifugal liquid pump (pump) in the cooling system ensures constant circulation of the coolant. The pump drive is most often realized using a belt or gears. Turbocharged and direct injection engines are usually equipped with an additional pump.
The thermostat is the main unit that regulates the flow of coolant, is usually installed between the inlet pipe of the radiator and the "water jacket", it is structurally made in the form of a bimetallic or electronic valve. The purpose of the thermostat is to maintain the specified operating temperature range of the coolant under all engine operating modes.
The heater radiator is very similar to the smaller cooling system radiator and is located in the passenger compartment. The fundamental difference is that the heater radiator transfers heat to the passenger compartment, while the cooling system radiator transfers heat to the environment.

Principle of operation

The principle of operation of liquid cooling of the engine is as follows: the cylinders are surrounded by a "water jacket" of coolant, which takes away excess heat and transfers it to the radiator, from where it is transferred to the atmosphere. The fluid, continuously circulating, ensures the optimum engine temperature.

The principle of operation of the engine cooling system

Cooling liquids - antifreeze, antifreeze and water - during operation form sediment and scale that disrupt the normal operation of the entire system.

Water is not chemically pure in principle (with the exception of distilled water) - it contains impurities, salts and all kinds of aggressive compounds. At elevated temperatures, they precipitate and form scale.

Unlike water, antifreezes do not create scale, but decompose during operation, and decomposition products have a negative effect on the operation of mechanisms: a corrosive deposit and layers of organic substances appear on the inner surfaces of metal elements.

In addition, various foreign contaminants can enter the cooling system: oil, detergents or dust. Also used for emergency repair of damages in radiators can get in.

All these contaminants settle on the internal surfaces of components and assemblies. They are characterized by poor thermal conductivity and clog the thin tubes and cells of the radiator, disrupting the efficient operation of the cooling system, which leads to overheating of the engine.

Video on how the motor cooling works, the principle of operation and malfunctions

Something else useful for you:

Flushing

Flushing the engine cooling system is a process that many drivers often neglect, which sooner or later can cause fatal consequences.

Signs that it's time to flush

If the arrow of the temperature gauge is not in the middle, but tends to the red zone while driving;
It is cold in the cabin, the heating stove does not give a sufficient temperature;
Radiator fan turns on too often

It is impossible to flush the cooling system with plain water, since impurities are concentrated in the system, which cannot be removed even by water heated to high temperatures.

Scale is removed with acid, and fats and organic compounds are removed exclusively with alkali, but it is impossible to pour both compositions into the radiator at the same time, since they are mutually neutralized according to the laws of chemistry. Manufacturers of flushing products, trying to solve this problem, have created a number of products that can be roughly divided into:

alkaline;
acidic;
neutral;
two-component.

The first two are too aggressive and are almost never used in their pure form, since they are dangerous for the cooling system and require neutralization after use. Less common are two-component types of cleaners containing both solutions - alkaline and acid, which are poured alternately.

The greatest demand is for neutral cleaners that do not contain strong alkalis and acids. These funds have varying degrees of effectiveness and can be used both for prophylaxis and for thorough flushing of the engine cooling system from heavy contamination.

Flushing the cooling system

Antifreeze, antifreeze or water is drained. Before that, you need to start the engine for a couple of minutes.
Fill the system with water and cleaner.
Turn on the engine for 5-30 minutes (depending on the brand of cleaner) and turn on the interior heating.
After the expiration of the time indicated in the instructions, the engine must be turned off.
Drain off used cleaner.
Flush with water or a special compound.
Fill in fresh coolant.

Flushing the cooling system is simple and affordable: even inexperienced car owners can perform them. This operation significantly extends the engine life and maintains its performance at a high level.

Malfunctions

There are a number of the most common engine cooling problems:

Airing the engine cooling system: remove the airlock.
Insufficient pump performance: replace the pump. Select the pump with the maximum impeller height.
Thermostat is faulty: it can be eliminated by replacing it with a new device.
Low performance of the coolant radiator: flushing the old one or replacing the standard one with a model with higher heat dissipation properties.
Insufficient performance of the main fan: Install a new fan with a higher performance.

Video - identification of malfunctions of the cooling system in a car service

Regular maintenance, timely replacement of the coolant guarantees long-term operation of the vehicle as a whole.

The modern car enthusiast is more and more interested in the device of the car. In the study of a car device, it is difficult to ignore such an important part as maintaining the temperature regime in the car engine. CO (Engine Cooling System), the most important component of any machine. The wear and productivity of the engine of the machine depend on the correctness of its functioning. Serviceable CO, significantly reduces the load on the working elements of the engine. To maintain the correct functioning of the system, it is necessary to have a good understanding of its components. After reviewing the helpful materials, you will be able to serve COs competently.

During the operation of the car, the working parts of the engine are capable of gaining a high temperature. To avoid overheating of the working parts, the car is equipped with a cooling system. The cooling system of the car significantly reduces the temperature of the working parts of the engine. Maintaining an optimal temperature regime is due to the working fluid. The working mixture circulates through special conductors, preventing overheating. The system, on all vehicles, performs a number of additional functions.

Cooling system functions.

Optimization of the temperature of the mixture for lubricating the working parts of the car.
Exhaust gas temperature regulation in the exhaust system.
Lowering the temperature of the mixture for the operation of the automatic transmission.
Lowering the air temperature in the car's turbine.
Heating the air flow in the heating system.

Today, there are several types of cooling systems. Systems, in particular, are separated from the method of lowering the temperature of the working parts.

Types of cooling systems.

Closed. In this system, the temperature drop is due to the working fluid.
Open (Air). In an open system, the temperature is reduced by air flow.
Combined. The cooling system under consideration combines two types of cooling. Particularly from the system manufacturer, the cooling is done jointly or sequentially.

The most popular in mechanical engineering has become the engine cooling system using coolant. The cooling system under consideration has become the most effective and practical for operation. The cooling system evenly lowers the temperature of the working parts of the engine. Let's consider the device and the way of functioning of the system, using the most popular example.

Regardless of the features of the engine, the design and functioning of the cooling system does not differ much. Thus, engines with different types of fuel have an almost identical temperature control system. The cooling system includes components that ensure its functioning. Each component is extremely important for full-fledged work. In case of malfunction of one component, the correct optimization of the temperature regime is violated.

Components of cooling systems.

Coolant heat exchanger.
Oil heat exchanger.
Fan.
Pumps. In particular, from the OS model, there may be several of them.
Working mixture tank.
Sensors.

For the functioning of the working mixture, there are special conductors in the system. The control of the system operation is carried out thanks to the central control system.

The heat exchanger lowers the temperature of the liquid by a flow of cold air. To change the heat output, the heat exchanger is equipped with a certain mechanism, which is a small tube.

Together with the standard transmitter, some manufacturers equip the system with a heat exchanger for oil and recycled gases. The oil heat exchanger reduces the temperature of the fluid that lubricates the working components. The second is necessary to lower the temperature of the exhaust mixture. Exhaust Circulation Regulator - Reduces the production temperature of the combined fuel and air. This reduces the amount of nitrogen produced during engine operation. A special compressor is responsible for the correct operation of the device in question. The compressor sets the working mixture in motion, moving it through the system. The device is built into the OS.

The heat exchanger is responsible for the opposite action. The device increases the temperature of the air flow operating through the system. To ensure maximum productivity, the mechanism is located on the coolant outlet from the vehicle engine.

Expansion barrel designed to fill the system with a working mixture. Thanks to this, fresh coolant enters the conductors, restoring the volume of the used one. Thus, the level of the mixture always remains necessary.

The movement of the coolant takes place thanks to the central pump. Depending on the manufacturer, the pump is driven in different ways. Most pumps are driven by a belt or gear. Some manufacturers equip the OS with another pump. An additional pump is required when equipping the mechanism with a compressor to cool the air flow. The engine control unit is responsible for the functioning of all pumps in the system.

A thermostat is provided to create the optimum fluid temperature. This device detects the volume of liquid (moving through the radiator) that needs to be cooled. Thus, the necessary temperature conditions are created for the correct operation of the engine. The device is located between the radiator and the mixture conductor.

Large displacement motors are equipped with electric thermostats. This type of device changes the temperature of the liquid in several stages. The device has several modes of operation: free, closed and intermediate. When the load on the engine becomes full, thanks to the electric drive, the thermostat is brought into free mode. In this case, the temperature is reduced to the required level. In particular, from the pressure on the engine, the thermostat operates in the mode of maintaining the optimum temperature.

The fan is responsible for improving the efficiency of regulating the temperature of the liquid. The fan drive differs depending on the OS model and manufacturer.

Fan drive types:

Mechanics. This type of drive establishes continuous contact with the hardened shaft of the engine.
Electrician. In this case, the fan is driven by an electric motor.
Hydraulics. A special hydraulically driven clutch directly activates the fan.

Due to the possibility of adjustment and a variety of operating modes, the most popular is the electric drive.

Sensors are important components of the aggregate. The level and temperature sensor of the coolant allows you to monitor the required parameters and restore them in a timely manner. Also, the device contains a central control unit and adjustment elements.

The coolant temperature sensor determines the indicator of the working fluid and converts it into digital format for transmission to the device. At the radiator outlet, a separate sensor is installed to expand the functionality of the cooling system.

The electrical unit receives readings from the sensor and transmits it to special devices. The block also changes the indicators for the impact, determining the required direction. For this, there is a special software installation in the block.

To carry out actions and adjust the temperature of the coolant, the mechanism is equipped with a number of special devices.

OS executive systems.

Thermostat temperature regulator.
Main and secondary compressor switch.
Fan mode control unit.
The block that regulates the operation of the OS after the engine stops.

The principles of the cooling system.

The control over the operation of the cooling system is carried out by the central engine control unit. Most cars are equipped with a system based on a certain algorithm. The necessary working conditions and the period of certain processes are determined using the corresponding indicators. Optimization takes place based on the indicators of the sensors (temperature and coolant level, lubricant temperature). Thus, optimal processes are set for maintaining the temperature regime in the car engine.

The central pump is responsible for the constant movement of the coolant along the conductors. Under pressure, the liquid moves continuously along the conductors of the OC. Thanks to this process, the temperature of the working parts of the engine decreases. Depending on the characteristics of a particular mechanism, several directions of movement of the mixture are distinguished. In the first case, the mixture is directed from the initial cylinder to the final one. In the second, from the outlet collector to the inlet.

Based on the temperature readings, the liquid flows in a narrow or wide arc. When starting the engine, working elements and fluid, including, have a low temperature. To quickly raise the temperature, the mixture moves in a narrow arc without cooling the radiator. During this process, the thermostat is in closed mode. Thus, operational warming up of the engine is achieved.

As the temperature of the engine elements rises, the thermostat goes into free mode (opening the cover). At the same time, the liquid begins to pass through the radiator, moving in a wide arc. The air flow in the radiator cools the heated liquid. An auxiliary cooling element can also be a fan.

After creating the required temperature, the mixture passes into the conductors located on the engine. While the vehicle is running, the temperature optimization process is constantly repeated.

On vehicles equipped with a turbine, a special cooling mechanism with two levels is installed. In this, there is a separation of the coolant conductors. One of the levels is responsible for cooling the car engine. The second one cools the air flow.

The cooling device is especially important for the proper operation of the vehicle. If it malfunctions, the engine may overheat and fail. Like any component of a car, the OS requires timely maintenance and care. One of the most important elements for maintaining the temperature regime is the coolant. This mixture must be changed regularly, according to the manufacturer's recommendations. In the event of malfunctions in the OS, it is not recommended to operate the car. This can expose the engine to high temperatures. In order to avoid serious malfunctions, it is necessary to quickly diagnose the device. Having studied the device and the principle of operation, you can determine the nature of the malfunction. If serious malfunctions occur, consult a professional. This knowledge will also be useful to you in this. Service the device in a timely manner and you will significantly increase its service life. Good luck with the useful material.

The engine cooling system is used to maintain normal thermal operation of engines by intensively removing heat from hot engine parts and transferring this heat to the environment.

The removed heat consists of a part of the heat released in the engine cylinders, which is not converted into work and is not carried away with the exhaust gases, and from the heat of friction work arising from the movement of engine parts.

Most of the heat is removed to the environment by the cooling system, a smaller part by the lubrication system and directly from the outer surfaces of the engine.

Forced heat removal is necessary because at high temperatures of gases in the engine cylinders (during the combustion process 1800–2400 ° C, the average temperature of gases during the operating cycle at full load 600–1000 ° C) the natural heat transfer to the environment is insufficient.

Violation of proper heat dissipation causes deterioration of lubrication of rubbing surfaces, oil burnout and overheating of engine parts. The latter leads to a sharp drop in the strength of the material of the parts and even their burning (for example, exhaust valves). When the engine overheats, the normal clearances between its parts are disrupted, which usually leads to increased wear, seizure and even breakdown. Engine overheating is also harmful because it causes a decrease in the filling ratio, and in gasoline engines, in addition, detonation combustion and spontaneous combustion of the working mixture.

Excessive cooling of the engine is also undesirable, since it entails condensation of fuel particles on the cylinder walls, deterioration of mixture formation and flammability of the working mixture, a decrease in its combustion rate and, as a consequence, a decrease in engine power and economy.

Cooling system classification

In automobile and tractor engines, depending on the working fluid, systems are used liquid and air cooling. The most widespread is liquid cooling.

With liquid cooling, the fluid circulating in the engine cooling system absorbs heat from the cylinder walls and combustion chambers and then transfers this heat using a radiator to the environment.

According to the principle of heat dissipation into the environment, cooling systems can be closed and open (flowing).

Liquid cooling systems for automotive engines have a closed cooling system, that is, a constant amount of fluid circulates in the system. In a flow-through cooling system, the heated liquid, after passing through it, is thrown into the environment, and a new one is taken for supply to the engine. The use of such systems is limited to marine and stationary engines.

Air cooling systems are open-loop. The cooling air, after passing through the cooling system, is discharged into the environment.

The classification of cooling systems is shown in Fig. 3.1.

According to the method of circulation of the liquid, the cooling system can be:

compulsory, in which the circulation is provided by a special pump located on the engine (or in the power plant), or the pressure under which the fluid is supplied to the power plant from the external environment;

thermosiphon, in which the circulation of the liquid occurs due to the difference in gravitational forces resulting from the different density of the liquid heated near the surfaces of the engine parts and cooled in the cooler;

combined, in which the most heated parts (cylinder heads, pistons) are forcedly cooled, and the cylinder blocks - according to the thermosiphon principle .

Rice. 3.1. Cooling system classification

Liquid cooling systems can be open or closed.

Open systems- systems communicating with the environment by means of a steam pipe.

Most automobile and tractor engines currently use closed systems cooling systems, i.e. systems separated from the environment by a steam-air valve installed in the radiator plug.

The pressure and, accordingly, the permissible temperature of the coolant (100–105 ° C) in these systems is higher than in open systems (90–95 ° C), as a result of which the difference between the temperatures of the liquid and the air sucked through the radiator and the heat transfer of the radiator increase. This reduces the size of the radiator and the power required to drive the fan and water pump. In closed systems, there is almost no evaporation of water through the steam outlet pipe and its boiling when the engine is running in high altitude conditions.

Liquid cooling system

In fig. 3.2 shows a diagram of a liquid cooling system with forced circulation of the coolant.

Cylinder block cooling jacket 2 and block heads 3, the radiator and pipes are filled with coolant through the filler neck. The liquid washes the walls of the cylinders and combustion chambers of a running engine and, when heated, cools them. Centrifugal pump 1 pumps fluid into the cylinder block jacket, from which the heated fluid enters the block head jacket and then is displaced into the radiator through the upper pipe. The liquid cooled in the radiator is returned to the pump through the lower branch pipe.

Rice. 3.2. Liquid cooling system diagram

The circulation of the liquid, depending on the thermal state of the engine, is changed by a thermostat 4. When the coolant temperature is below 70–75 ° C, the main thermostat valve is closed. In this case, the liquid does not enter the radiator. 5 , and circulates along a small circuit through the branch pipe 6, which contributes to the rapid warming up of the engine to the optimal thermal regime. When the thermostat thermostat element heats up to 70–75 ° C, the main thermostat valve starts to open and allows water to flow into the radiator, where it is cooled. The thermostat opens completely at 83–90 ° С. From this moment on, the water circulates along the radiator, i.e. large, circuit. The temperature regime of the engine is also regulated by means of rotary louvers, by changing the air flow created by the fan 7 and passing through the radiator.

In recent years, the most effective and rational way to automatically control the temperature of the engine is to change the performance of the fan itself.

Elements of the fluid system

Thermostat designed to provide automatic control of the coolant temperature while the engine is running.

To quickly warm up the engine when it is started, a thermostat is installed in the outlet pipe of the cylinder head jacket. It maintains the desired coolant temperature by varying the rate at which it circulates through the radiator.

In fig. 3.3 shows a bellows-type thermostat. It consists of a body 2, corrugated cylinder (bellows), valve 1 and the stem connecting the bellows to the valve . The bellows is made of thin brass and is filled with a volatile liquid (for example, ether or a mixture of ethyl alcohol and water). Windows located in the thermostat housing 3 depending on the temperature of the coolant, they can either remain open or be closed valves .

When the temperature of the coolant washing the bellows is below 70 ° C, the valve 1 closed and windows 3 are open. As a result, the coolant does not enter the radiator, but circulates inside the engine jacket. When the coolant temperature rises above 70 ° C, the bellows, under the vapor pressure of the liquid evaporating in it, lengthens and begins to open the valve 1 and gradually cover the windows with valves 3. At a coolant temperature above 80-85 ° C, the valve 1 opens completely, the windows close completely, as a result of which all the coolant circulates through the radiator. Currently, this type of thermostat is used very rarely.

Rice. 3.3. Bellows thermostat

Now engines are fitted with thermostats, in which the damper 1 opens with the expansion of the solid filler - ceresin (Fig. 3.4). This substance expands with increasing temperature and opens the damper 1 , ensuring the flow of coolant into the radiator.

Rice. 3.4. Solid fill thermostat

Radiator is a heat dissipating device designed to transfer the heat of the coolant to the surrounding air.

Radiators of automobile and tractor engines consist of upper and lower reservoirs, interconnected by a large number of thin tubes.

To enhance the transfer of heat from the coolant to the air, the fluid flow in the radiator is directed through a series of narrow tubes or channels blown with air. Radiators are made of materials that conduct well and give off heat (brass and aluminum).

Depending on the design of the cooling grille, radiators are divided into tubular, plate and honeycomb.

Currently, the most widespread are tubular radiators... The cooling grille of such radiators (Fig. 3.5a) consists of vertical tubes of oval or round cross-section passing through a row of thin horizontal plates and soldered to the upper and lower radiator reservoirs. The presence of fins improves heat transfer and increases the rigidity of the radiator. Tubes of oval (flat) cross-section are preferable, since with the same cross-section of the jet, their cooling surface is larger than the cooling surface of round tubes; in addition, when the water in the radiator freezes, the flat tubes do not break, but only change the shape of the cross section.

Rice. 3.5. Radiators

V plate radiators the cooling grill (Fig.3.5b) is designed so that the coolant circulates in space , formed by each pair of plates welded together along the edges. The upper and lower ends of the plates are also soldered into the openings of the upper and lower radiator reservoirs. The air cooling the radiator is sucked in by the fan through the passages between the soldered fins. To increase the cooling surface, the plates are usually wavy. Plate radiators have a larger cooling surface than tubular radiators, but due to a number of disadvantages (rapid contamination, a large number of soldered seams, the need for more careful maintenance), they are used relatively rarely.

Cellular radiator refers to radiators with air pipes (Fig.3.5c). In the grille of a honeycomb radiator, air passes through horizontal, circular tubes, washed from the outside by water or coolant. To make it possible to solder the ends of the tubes, their edges are expanded so that in cross-section they have the shape of a regular hexagon.

The advantage of cellular radiators is a large cooling surface than in other types of radiators. Due to a number of disadvantages, most of which are the same as those of plate radiators, honeycomb radiators are extremely rare nowadays.

A steam valve is installed in the radiator filler cap 2 and air valve 1 , which serve to maintain the pressure within the specified limits (Fig. 3.6).

Rice. 3.6. Radiator cap

Water pump ensures circulation of coolant in the system. As a rule, small-sized single-stage low-pressure centrifugal pumps with a capacity of up to 13 m 3 / h, creating a pressure of 0.05–0.2 MPa, are installed in cooling systems. Such pumps are structurally simple, reliable and provide high performance (Fig. 3.7).

The pump casing and impeller are cast from magnesium, aluminum alloys, the impeller, in addition, from plastics. In water pumps of automobile engines, semi-closed impellers are usually used, that is, impellers with one disc.

The impellers of centrifugal water pumps are often mounted on the same shaft as the fan. In this case, the pump is installed in the upper front part of the engine, it is driven from the crankshaft using a V-belt drive.

Rice. 3.7. Water pump

The belt drive can also be used when installing the centrifugal pump separately from the fan. In some engines of trucks and tractors, the water pump is driven from the crankshaft by a gear transmission. The shaft of a centrifugal water pump is usually mounted on rolling bearings and equipped with simple or self-adjusting oil seals for sealing the working surface.

Fan in liquid cooling systems, they are installed to create an artificial air flow passing through the radiator. Fans of automobile and tractor engines are divided into two types: a) with blades stamped from sheet steel, attached to the hub; b) with blades, which are cast in one piece with the hub.

The number of fan blades varies from four to six. Increasing the number of blades above six is impractical, since the fan performance increases very insignificantly. The fan blades can be flat and convex.

The working processes of an automobile engine take place at high temperatures, therefore, to ensure its performance for a long time, it is necessary to remove excess heat. This function is provided by the cooling system (CO). In the cold season, this heat is used to heat the passenger compartment.

In vehicles with turbocharging, the function of the cooling system is to lower the temperature of the air supplied to the combustion chamber. Additionally, in one of the circles from the cooling system of some car models equipped with an automatic transmission (automatic transmission), oil cooling in the automatic transmission is switched on.

Two main types of CO are installed in cars: water and air. The principle of operation of a water-cooled engine cooling system is to heat the fluid from the power plant or other components and release such heat to the atmosphere through the radiator. The air system uses air as the working cooler. Both options have their merits and demerits.

However, a cooling system with liquid circulation has become more widespread.

Air CO

Air cooling

The main advantages of this layout include the simplicity of the system design and maintenance. Such CO practically does not increase the mass of the power unit, and is also not capricious to changes in the ambient temperature. The negative includes a significant take-off of motor power by the fan drive, an increased noise level during operation, poorly balanced heat removal from individual units, the impossibility of using the engine block system, the impossibility of accumulating heat removed for further use, for example, heating the passenger compartment.

Liquid CO

Liquid cooling

The system using heat removal using a special fluid, due to its design, can effectively remove excess heat from mechanisms and individual structural parts. Unlike air, the device of the engine cooling system with liquid contributes to a faster set of operating temperature at startup. Also, motors with antifreeze are much quieter and less prone to detonation.

Cooling system elements

Let's take a closer look at how the engine cooling system works on modern cars. There are no significant differences between gasoline and diesel engines in this regard.

The structural cavities of the cylinder block act as a "jacket" for cooling the engine. They are located around areas from which heat needs to be removed. For faster drainage, a radiator is installed, consisting of curved copper or aluminum tubes. A large number of additional ribs accelerate the heat transfer process. These ribs increase the cooling plane.

A fan blowing air is placed in front of the radiator. The inflow of colder flows begins after the closure of the electromagnetic clutch. It turns on when the fixed temperature values are reached.

Thermostat operation

The continuous circulation of the coolant is ensured by the operation of the centrifugal pump. The belt or gear transmission for it receives rotation from the power plant.

The thermostat controls the flow directions.

If the temperature of the coolant is not high, then the circulation takes place in a small circle, without the inclusion of a radiator in it. If the permissible thermal regime is exceeded, then the thermostat starts up the flow in a large circle with the participation of the radiator.

For closed hydraulic systems, it is common to use expansion tanks. Such a tank is also provided in the vehicle CO.

Coolant circulation

The interior is warmed up using a heater radiator. In this case, warm air does not escape into the atmosphere, but is launched inside the car, creating comfort for the driver and passengers in the cold season. For greater efficiency, such an element is installed practically at the fluid outlet from the cylinder block.

The driver receives information about the state of the cooling system using a temperature sensor. Signals are also sent to the control unit. He can independently connect or disconnect executive devices to maintain a balance in the system.

System operation

Antifreezes with a variety of additives, including anti-corrosion ones, are used as coolants. They help to increase the durability of units and parts used in CO. Such a liquid is forcibly pumped through the system by a centrifugal pump. Movement begins from the cylinder block, the hottest point.

First, there is a movement in a small circle with a closed thermostat without entering the radiator, because even the operating temperature for the motor has not yet been reached. After entering the operating mode, circulation occurs in a large circle, where the radiator can be cooled with a counter flow or with the help of a plug-in fan. After that, the fluid returns to the "jacket" around the cylinder block.

There are cars using two cooling circuits.

The first lowers the temperature of the engine, and the second takes care of the charge air, cooling it to form a fuel mixture.