How the engine cooling system works. Why you need engine cooling and how it works Why you need a car engine cooling system

for stable and uptime ICE (engine internal combustion) in each car, the engine cooling system is responsible. After all, if cooling does not occur properly, this can lead to overheating of the internal combustion engine, and then to costly repairs. This article will focus on the engine cooling system, its principle of operation and device, as well as solving some problems that arise during operation.

Working principle and main function

The main function of the cooling system is to remove excess heat from the internal combustion engine and prevent it from overheating. And in winter period time, it provides heating of the car interior with the help of a heater radiator. IN standard systems circulation, it cools the heated parts, and in modern cars performs a series additional features, such as:

1. Cools working fluid automatic transmission.
2. Cools the oil in the lubrication system.
3. Heats up the air.
4. Cools exhaust crankcase gases.

The principle of operation of the engine cooling system is as follows: the cylinders in the cylinder block are surrounded by a so-called "water cushion" of coolant (coolant), which constantly circulates, thereby achieving the optimum operating temperature.
Antifreeze and antifreeze are used as coolants, and as an exception, distilled water can be added.

Over time, these liquids precipitate, which negatively affects normal cooling. In order to prevent this, the coolant should be replaced in accordance with the regulations service book. To understand how the engine cooling system works, the first step is to consider the device diagram.

Device diagram

The engine cooling system circuit consists of the following direct parts:

• cooling radiator basic;
• radiator fan;
• water pump (pump);
• cooling jacket(water cushion);
• thermostat ;
• heater radiator;
• expansion tank.

Such schemes are almost similar for diesel and gasoline engines, there is only a slight difference in the very principle of operation. diesel engine. Every detail plays important role for stable and correct operation engine cooling systems, and if one of them fails, this can lead to overheating of the internal combustion engine, and as a result lead to time-consuming and costly repairs. Each element must be considered separately.

Radiator and fan

The radiator of the engine cooling system is one of the main elements and is designed to dissipate into the atmosphere the heat removed from the internal combustion engine by the coolant, and is also responsible for the temperature of the engine. Structurally, the radiator is made of many tubes with fins that increase heat transfer.

The engine cooling fan is designed to improve the efficiency of the radiator. There are 3 types, depending on the drive:

1. Electric .
2. Hydraulic .
3. Mechanical.

The most common electrically driven fans. The operation of the fan is activated when the coolant sensor is triggered, thereby increasing the air flow. In the case when the radiator cells are clogged, you can try to clean them with special means sometimes this method helps.

Water pump

The pump in the car is designed for constant circulation, working coolant. In a water pump, there are often two drives: belt or gear. In cars with an internal combustion engine additionally equipped with a turbocharger, in addition to the main pump, an additional one is installed, which provides more efficient cooling of the turbocharger and charge air.

A “water jacket” is a system of channels for the circulation of coolant that pass through the cylinder head (cylinder head) and serve to remove excess heat, thereby cooling the internal combustion engine.

Thermostat

The next not unimportant node is the thermostat. Its main purpose in the engine cooling system is to regulate coolant flows, accelerate engine warm-up and maintain the set operating temperature in all modes ICE operation. The thermostat is often installed in the pipe coming out of the radiator.

At a high temperature of the internal combustion engine in the thermostat, the valve opens and the coolant circulates in a large circle, connecting the radiator to work. In other words, in the case when the thermostat is closed, it moves the coolant in a small circle in the "water jacket", and when it is open, it directs the liquid to the radiator.

Visually, the heater radiator is similar to the main radiator, but it is smaller and is installed inside the car. Its main task is to heat the car interior in the winter. By the way, its breakdown is a common malfunction in winter, and, for example, in Kalina cars, it often fails due to inconvenient fastening, and as a result, heat ceases to flow into the car interior.

Expansion tank with plug-valve

The expansion tank of the engine cooling system is designed to maintain required level cool. Over time, during operation and a change in the temperature of the liquid, its volume also changes, which must be compensated by topping up the coolant. The level must always be monitored and in the event of a minimum acceptable level top it up. Also important detail is the cap-valve of the expansion tank.

The most common malfunctions

During the operation of the vehicle, there may be various faults with cooling. The most common ones should be considered: air in the cooling system, pressure in the system, breakdown of the thermostat or pump, leak.

Airing is perhaps the most common malfunction that occurs, its fault is the air that got into the system during the topping up of the coolant. In order to eliminate, it is necessary to bleed the air.

Excessive pressure in the engine cooling system can damage rubber pipes or radiators. Simply put, they can simply break. Permissible indicators vary from 1.2 to 2.0 atmospheres. The cap-valve of the expansion tank is responsible for normal pressure, which, if necessary, opens and releases excess steam.

In the event of failure of the thermostat or pump, such a breakdown is eliminated by replacing it with new part. There are cases when a motorist has found traces of a leak, and it is still necessary to get to the nearest service station, then in order not to overheat the internal combustion engine, a sealant is used for the engine cooling system. It is intended to create a seal at the site of a leak, however, it is often not recommended to use it, this is only an extreme measure.

You can repair the engine cooling system yourself, but if the motorist has few skills, it is better to entrust this matter to specialists from service stations.

Outcome

It's time to sum up the information presented. ICE cooling plays an important role in the correct and stable operation car. You should not forget to monitor the condition of the nodes responsible for cooling, and as the coolant leaves the expansion tank, top it up.

Every car uses an internal combustion engine. Liquid cooling systems are widely used - only on the old "Zaporozhets" and the new "Tata" air blowing is used. It should be noted that the circulation scheme on all machines is almost similar - the same elements are present in the design, they perform identical functions.

Small cooling circle

In the scheme of the cooling system of the internal combustion engine, there are two circuits - small and large. In some ways, it is similar to human anatomy - the movement of blood in the body. The liquid moves in a small circle when it is necessary to produce fast warm-up up to operating temperature. The problem is that the motor can function normally in a narrow temperature range - about 90 degrees.

You can not increase or decrease it, as this will lead to violations - the ignition timing will change, fuel mixture will burn out at the wrong time. The circuit includes a radiator for the interior heater - after all, it is necessary that the inside of the car be warm as soon as possible. The supply of hot antifreeze is blocked with a tap. Its location depends on specific vehicle- on the partition between the salon and engine compartment, in the glove box area, etc.

Large cooling circuit

In this case, the main radiator is also turned on. It is installed in the front of the car and is designed to urgently reduce the temperature of the fluid in the engine. If the car has air conditioning, then its radiator is installed nearby. On Volga and Gazelle cars, an oil cooler is used, which is also placed in front of the car. A fan is usually placed on the radiator, which is driven by an electric motor, a belt or a clutch.

Liquid pump in the system

This device is included in the Gazelle coolant circulation circuit and any other car. The drive can be carried out as follows:

1. From the timing belt.
2. From the alternator belt.
3. From a separate belt.

The design consists of the following elements:

1. Metal or plastic impeller. The efficiency of the pump depends on the number of blades.
2. Housing - usually made of aluminum and its alloys. The fact is that this particular metal works well in aggressive conditions, corrosion practically does not affect it.
3. The pulley for installing the drive belt is toothed or wedge-shaped.
4. Shaft - a steel rotor, at one end of which there is an impeller (inside), and outside a pulley for installing a drive pulley.
5. Bronze bushing or bearing - lubrication of these elements is carried out using special additives that are available in antifreeze.
6. The seal prevents fluid from leaking out of the cooling system.

Thermostat and its features

It is difficult to say which element provides the most efficient circulation of fluid in the cooling system. On the one hand, the pump creates pressure and the antifreeze moves through the nozzles with its help.

But on the other hand, if there were no thermostat, the movement would occur exclusively in a small circle. The design contains the following elements:

1. Aluminum body.
2. Outlets for connection with nozzles.
3. Bimetallic type plate.
4. Mechanical valve with return spring.

The principle of operation is that at temperatures below 85 degrees, the liquid moves only along a small contour. In this case, the valve inside the thermostat is in a position in which antifreeze does not enter the large circuit.

As soon as the temperature reaches 85 degrees, it will begin to deform. It acts on the mechanical valve and opens access to the antifreeze to the main radiator. As soon as the temperature drops, the thermostat valve will return to its original position under the action of a return spring.

Expansion tank

The cooling system of an internal combustion engine has expansion tank. The fact is that any liquid, including antifreeze, increases volume when heated. As it cools, the volume decreases. Therefore, some kind of buffer is needed, which will store not a large number of liquid so that there is always plenty of it in the system. It is with this task that the expansion tank copes - the excess splashes out there during heating.

Expansion tank cap

Another indispensable component of the system is a cork. There are two types of construction - hermetic and non-hermetic. In the event that the latter is used on the car, the plug of the expansion tank has only a drain hole through which the pressure in the system is balanced.

But if a sealed system is used, then there are two valves in the plug - an inlet valve (takes air from the atmosphere inside, operates at a pressure below 0.2 bar) and an exhaust valve (operates at a pressure above 1.2 bar). It expels excess air from the system.

It turns out that the pressure in the system is always greater than in the atmosphere. This allows you to slightly increase the boiling point of antifreeze, which favorably affects the operation of the engine. This is especially good for driving in traffic jams in urban areas. An example of a sealed system is VAZ-2108 cars and the like. Leaky - models of the classic VAZ series.

Radiator and fan

Coolant circulates through the main radiator, which is installed at the front of the vehicle. Such a place was not chosen by chance - when driving with high speed the radiator cells are blown by an oncoming air flow, which reduces the engine temperature. A fan is installed on the radiator. Most of these devices have On "Gazelles", for example, clutches are often used, similar to those that are placed on air conditioning compressors.

The electric fan is turned on using a sensor installed at the bottom of the radiator. Can be used on injection machines a signal from a temperature sensor, which is located on the thermostat housing or in the engine block. The most simple circuit switching on contains only one thermal switch - it has normally open contacts. As soon as the temperature reaches 92 degrees at the bottom of the radiator, the contacts inside the switch will close and voltage will be applied to the fan motor.

Cabin heater

This is the most important part when viewed from the perspective of the driver and passengers. Comfort when driving depends on the efficiency of the stove. winter time of the year. The heater is part of the coolant circulation circuit and consists of the following components:

1. Electric motor with impeller. It is turned on according to a special scheme in which there is a constant resistor - it allows you to change the speed of the impeller.
2. The radiator is the element through which the hot antifreeze.
3. The crane - is intended for opening and closing of supply of antifreeze in a radiator.
4. The duct system allows you to direct hot air in the right direction.

The scheme of circulation of the coolant through the system is such that when only one inlet to the radiator is closed, hot antifreeze will not get into it in any way. There are cars in which there is no stove tap - there is always hot antifreeze inside the radiator. And in summer time air ducts are simply closed and heat is not supplied to the cabin.

Today from our regular column " How it works» You will learn the device and the principle of operation engine cooling systems, what is the thermostat for And radiator and also why it is not widely used air cooling system.

Cooling system internal combustion engine performs heat dissipation from engine parts and transfer it to environment. In addition to the main function, the system performs a number of secondary ones: oil cooling in the lubrication system; air heating in the heating and air conditioning system; exhaust gas cooling, etc.

When burning working mixture, the temperature in the cylinder can reach 2500°C, while the working internal combustion engine temperature is 80-90°C. It is to maintain the optimal temperature regime that there is a cooling system, which can be of the following types, depending on the coolant: liquid, air and combined . It should be noted that liquid system in its pure form is almost never used, as it is not able to maintain the operation of modern engines in optimal thermal conditions for a long time.

Combined system engine cooling:

In a combined cooling system, as a coolant, often water is used, as it has a high specific heat capacity, availability and harmlessness to the body. However, water has a number significant shortcomings: scale formation and freezing at low temperatures. In the winter season, it is necessary to fill the cooling system with low-freezing liquids - antifreezes ( aqueous solutions ethylene glycol, mixtures of water with alcohol or glycerin, with hydrocarbon additives, etc.).

The cooling system in question consists of: a liquid pump, a radiator, a thermostat, an expansion tank, a cooling jacket for cylinders and heads, a fan, a temperature sensor and supply hoses.

It is worth mentioning that the cooling of the engine is forced, which means that excess pressure is maintained in it (up to 100 kPa), as a result of which the boiling point of the coolant rises to 120°C.

When starting a cold engine, it gradually warms up. At first, the coolant, under the action of a liquid pump, circulates in a small circle, that is, in the cavities between the walls of the cylinders and the walls of the engine (cooling jacket), without getting into the radiator. This limitation is necessary to quickly introduce the engine into an efficient thermal regime. When the engine temperature exceeds the optimum values, the coolant begins to circulate through the radiator, where it is actively cooled (called large circle of circulation).

Device and principle of operation:

LIQUID PUMP . The pump provides forced circulation liquids in the engine cooling system. The most commonly used centrifugal type pumps. The shaft 6 of the pump is installed in the cover 4 using a bearing 5. At the end of the shaft, a cast iron impeller 1 is pressed in. When the pump shaft rotates, the coolant flows through the pipe 7 to the center of the impeller, is captured by its blades, and is thrown to the pump housing 2 under the action of centrifugal force and through window 3 in the housing is sent to the cooling jacket of the engine block.

RADIATOR ensures the removal of heat from the coolant to the environment. The radiator consists of upper and lower tanks and a core. It is mounted on a car on rubber cushions with springs. The most common tubular and plate radiators. In the former, the core is formed by several rows of brass tubes passed through horizontal plates, which increase the cooling surface and give the radiator rigidity. In the second, the core consists of one row of flat brass tubes, each of which is made of corrugated plates soldered together at the edges. The top tank has a filler neck and a steam pipe. The neck of the radiator is hermetically sealed with a plug that has two valves: a steam valve to reduce pressure when the liquid boils, which opens at an overpressure of more than 40 kPa (0.4 kgf / cm2), and an air valve that allows air to enter the system when the pressure decreases due to cooling of the liquid and thereby protects the radiator tubes from flattening by atmospheric pressure. Used and aluminum radiators: They cheaper and easier, but heat transfer properties and reliability below .

The coolant "running" through the radiator tubes is cooled when moving with an oncoming air flow.

FAN reinforces air flow through the core of the radiator. The fan hub is mounted on the fluid pump shaft. Together they are driven by a pulley. crankshaft belts. The fan is enclosed in a casing mounted on the radiator frame, which helps to increase the speed of the air flow passing through the radiator. Most often, four- and six-blade fans are used.

SENSOR coolant temperature refers to the control elements and is designed to set the value of the controlled parameter and its further conversion into an electrical impulse. The electronic control unit receives this impulse and sends certain signals executive devices. Using the coolant sensor, the computer determines the amount of fuel required for normal operation ICE. Also, based on the readings of the coolant temperature sensor, the control unit generates a command to turn on the fan.

Air system cooling:

In the air cooling system, heat is removed from the walls of the combustion chambers and engine cylinders by forced air flow created by a powerful fan. This cooling system is the simplest, since it does not require intricate details and control systems. The intensity of the air cooling of the engines significantly depends on the organization of the direction of the air flow and the location of the fan.

IN inline engines fans are located in front, on the side or combined with a flywheel, and in V-shaped ones - usually in the collapse between the cylinders. Depending on the location of the fan, the cylinders are cooled by air that is forced or sucked through the cooling system.

Optimum engine temperature air-cooled is considered to be such at which the temperature of the oil in lubrication system engine temperature is 70... 110°C in all engine operating modes. This is possible provided that up to 35% of the heat released during the combustion of fuel in the engine cylinders is dissipated into the environment with the cooling air.

The air cooling system reduces the engine warm-up time, provides stable heat removal from the walls of the combustion chambers and engine cylinders, is more reliable and easy to operate, easy to maintain, more technologically advanced rear location engine, engine overcooling is unlikely. However, the air cooling system increases dimensions engine, creates increased noise during engine operation, is more difficult to manufacture and requires the use of better fuels and lubricants. The heat capacity of air is low, which does not allow a large amount of heat to be uniformly removed from the engine and, accordingly, to create compact powerful power plants.

Cooling system- this is a set of devices that provide forced removal of heat from heating parts of the engine.

The need for cooling systems for modern engines is due to the fact that the natural dissipation of heat by the outer surfaces of the engine and heat removal into the circulating engine oil do not provide optimal temperature conditions for the operation of the engine and some of its systems. Overheating of the engine is associated with a deterioration in the process of filling the cylinders fresh charge, oil burning, increased friction losses and even piston seizure. On gasoline engines there is also a danger of glow ignition (not from a spark of a candle, but due to high temperature combustion chambers).

The cooling system must ensure automatic maintenance of the optimal thermal regime of the engine at all speed and load modes of its operation at an ambient temperature of -45 ... +45 ° C, rapid warm-up of the engine to operating temperature, minimum power consumption for actuating the system units, low weight and small overall dimensions, operational reliability determined by the service life, simplicity and ease of maintenance and repair.

On modern wheeled and tracked vehicles Oh air and liquid cooling systems are used.

When using an air cooling system (Fig. a), heat from the head and cylinder block is transferred directly to the air blowing them. Through the air jacket formed by the casing 3, the cooling air is driven by the fan 2, driven by the crankshaft using a belt drive. To improve heat dissipation, cylinders 5 and their heads are equipped with ribs 4. The intensity of cooling is regulated by special air dampers 6, controlled automatically by air thermostats.

Most modern engines have a liquid cooling system (fig. b). The system includes cooling jackets 11 and 13, respectively, of the head and cylinder block, radiator 18, upper 8 and lower 16 connecting pipes with hoses 7 and 15, liquid pump 14, distribution pipe 72, thermostat 9, expansion (compensation) tank 10 and fan 77. Coolant (water or antifreeze - antifreeze) is in the cooling jacket, radiator and pipes.

Rice. Schemes of air (a) and liquid (b) engine cooling systems:
1 - belt drive; 2, 17 - fans; 3 - casing; 4 - ribs of the cylinder; 5 - cylinder; 6- air damper; 7, 15 - hoses; 8, 16 - upper and lower connecting pipes; 9 - thermostat; 10 - expansion tank; 77, - cooling jackets for the head and cylinder block; 12 - distribution pipe; 14 - liquid pump; 18 - radiator

When the engine is running, a crankshaft-driven fluid pump circulates coolant through the system. Through the distribution pipe 12, the liquid is first directed to the most heated parts (cylinders, block head), cools them and enters the radiator 18 through the pipe 8. In the radiator, the liquid flow branches through the tubes into thin streams and is cooled by air blown through the radiator. The cooled liquid from the lower tank of the radiator through pipe 16 and hose 15 again enters the liquid pump. The flow of air through the radiator is usually created by a fan 77 driven by a crankshaft or a special electric motor. On some tracked vehicles, an ejection device is used to ensure air flow. The principle of operation of this device is to use the energy of exhaust gases flowing at high speed from the exhaust pipe and entraining air.

Regulates the circulation of liquid in the radiator, maintaining the optimum temperature of the engine, thermostat 9. The higher the temperature of the liquid in the jacket, the more open the thermostat valve and more liquid enters the radiator. At a low engine temperature (for example, immediately after starting it), the thermostat valve is closed, and the liquid is not directed to the radiator (through a large circulation circle), but immediately into the pump intake cavity (in a small circle). This ensures that the engine warms up quickly after starting. The intensity of cooling is also regulated by means of shutters installed at the inlet or outlet of the air path. The greater the degree of closing of the shutters, the less air passes through the radiator and worse cooling liquids.

In the expansion tank 10, located above the radiator, there is a supply of liquid to compensate for its loss in the circuit due to evaporation and leaks. In the upper cavity of the expansion tank, the steam formed in the system is often removed from the upper radiator manifold and cooling jacket.

Liquid cooling compared to air has the following benefits: easier engine start-up at low ambient temperatures, more uniform engine cooling, the possibility of using block cylinder structures, simplification of the layout and the possibility

insulation of the air path, less noise from the engine and lower mechanical stresses in its parts. At the same time, a liquid cooling system has a number of disadvantages, such as a more complex engine and system design, the need for coolant and more frequent oil changes, the risk of fluid leakage and freezing, increased corrosive wear, significant fuel consumption, more complex maintenance and repair, and (in some cases) increased sensitivity to changes in ambient temperature.

Liquid pump 14 (see Fig. b) circulates the coolant in the system. Usually centrifugal vane pumps are used, but sometimes gear and piston pumps. The thermostat 9 can be one- and two-valve with a liquid thermo-force element or an element containing a solid filler (ceresin). In any case, the material for the thermal force element must have a very high coefficient of volumetric expansion, so that when heated, the thermostatic valve stem can move a fairly large distance.

In practice, all engines of liquid-cooled ground vehicles are equipped with so-called closed cooling systems, which do not have a permanent connection with the atmosphere. In this case, excess pressure is formed in the system, which leads to an increase in the boiling point of the liquid (up to 105 ... 110 ° C), an increase in cooling efficiency and a decrease in losses, as well as a decrease in the likelihood of air and steam bubbles appearing in the liquid flow.

Maintaining the necessary overpressure in the system and providing access to atmospheric air during rarefaction is carried out using a double steam-air valve, which is installed at the highest point fluid system(usually in the filler cap of the expansion tank or radiator). The steam valve opens, allowing excess steam to escape into the atmosphere, if the pressure in the system exceeds atmospheric pressure by 20 ... 60 kPa. Air valve opens when the pressure in the system decreases by 1 ... 4 kPa compared to atmospheric (after the engine is stopped, the coolant cools down and its volume decreases). The pressure drops at which the valves open are provided by the selection of the parameters of the valve springs.

In liquid ventilation system cooling, the radiator is washed by the air flow created by the fan. Depending on the mutual arrangement of the radiator and the fan, the following types of fans can be used: axial, centrifugal and combined, creating both axial and radial air flows. Axial fans are installed in front of the radiator or behind it in a special air supply duct. TO centrifugal fan air is supplied along the axis of its rotation, and removed - along the radius (or vice versa). When the radiator is located in front of the fan (in the suction area), the air flow in the radiator is more uniform, and the air temperature is not increased due to its mixing by the fan. When the radiator is located behind the fan (in the discharge area), the air flow in the radiator is turbulent, which increases the cooling intensity.

On heavy wheeled and tracked vehicles, the fan is usually driven by the engine crankshaft. Cardan, belt and gear (cylindrical and bevel) transmissions can be used. In order to reduce dynamic loads on the fan in its drive from the crankshaft, unloading and damping devices in the form of torsion rollers, rubber, friction and viscous couplings, as well as fluid couplings are often used. For fan drive relative small engines Special electric motors are widely used, which are powered from the onboard electrical system. This usually reduces the weight power plant and simplifies its layout. In addition, the use of an electric motor to drive the fan allows you to adjust the frequency of its rotation, and hence the intensity of cooling. At low coolant temperatures it is possible automatic shutdown fan.

Radiators connect the air and liquid paths of the cooling system with each other. The purpose of radiators is to transfer heat from the coolant atmospheric air. The main parts of the radiator are the inlet and outlet manifolds, as well as the core (cooling grid). The core is made of copper, brass or aluminum alloys. According to the type of core, the following types of radiators are distinguished: tubular, tubular-lamellar, tubular-tape, lamellar and honeycomb.

In cooling systems of wheeled and tracked vehicles most widespread received tubular-plate and tubular-tape radiators. They are rigid, durable, manufacturable and have high thermal efficiency. The tubes of such radiators have, as a rule, a flat-oval section. Tubular-lamellar radiators can also consist of round or oval tubes. Sometimes flat-oval tubes are placed at an angle of 10 ... 15 ° to air flow, which contributes to the turbulence (swirl) of air and increases the heat transfer of the radiator. Plates (tapes) can be smooth or corrugated, with pyramidal protrusions or bent notches. The corrugation of the plates, the application of notches and protrusions increase the cooling surface and provide a turbulent flow of air between the tubes.

Rice. Lattices of tubular-lamellar (a) and tubular-tape (b) radiators

The cooling system is designed to cool engine parts that are heated as a result of its operation. On modern cars, the cooling system, in addition to the main function, performs a number of other functions, including:

Depending on the method of cooling, the following types of cooling systems are distinguished: liquid ( closed type), air ( open type) and combined. In system liquid cooling heat from the heated parts of the engine is removed by the fluid flow. The air system uses air flow for cooling. The combined system combines liquid and air systems.

On cars, the most common liquid cooling system. This system ensures uniform and efficient cooling and also has a lower noise level. Therefore, the device and principle of operation of the cooling system are considered on the example of a liquid cooling system.

The design of the cooling system for gasoline and diesel engines are similar. The engine cooling system includes many elements, including a coolant radiator, an oil cooler, a heater heat exchanger, a radiator fan, centrifugal pump, as well as an expansion tank and a thermostat. The engine cooling jacket is included in the cooling system circuit. Control elements are used to regulate the operation of the system.

The radiator is designed to cool the heated coolant with air flow. To increase heat transfer, the radiator has a special tubular device.

Along with the main radiator, an oil cooler and an exhaust gas recirculation cooler can be installed in the cooling system. Oil radiator serves to cool the oil in the lubrication system.

The exhaust gas recirculation cooler cools the exhaust gases, thereby reducing the combustion temperature. fuel-air mixture and the formation of nitrogen oxides. The exhaust gas cooler is operated by an additional coolant circulation pump included in the cooling system.

The heater heat exchanger performs the opposite function of the cooling system radiator. The heat exchanger heats the air passing through it. For effective work the heater heat exchanger is installed directly at the outlet of the heated coolant from the engine.

To compensate for the change in coolant volume due to temperature, an expansion tank is installed in the system. Filling the system with coolant is usually done through the expansion tank.

Coolant circulation in the system is provided by a centrifugal pump. In everyday life, a centrifugal pump is called pomp. The centrifugal pump may have various drive: gear, belt, etc. On some engines equipped with a turbocharger, an additional coolant circulation pump connected by the engine control unit is installed to cool the charge air and the turbocharger.

The thermostat is designed to regulate the amount of coolant passing through the radiator, which ensures optimal temperature regime in system. The thermostat is installed in the pipe between the radiator and the "cooling jacket" of the engine.

On powerful engines an electrically heated thermostat is installed, which provides two-stage control of the coolant temperature. To do this, the design of the thermostat provides for three operating positions: closed, partially open and fully open. At full load on the engine with electric heating thermostat is fully opened. In this case, the temperature of the coolant is reduced to 90 ° C, the tendency of the engine to detonate decreases. In other cases, the coolant temperature is maintained within 105°C.

The radiator fan serves to increase the intensity of cooling of the liquid in the radiator. The fan can have a different drive:

• mechanical ( permanent connection with crankshaft engine);
• electric ( controlled electric motor);
• hydraulic ( fluid coupling).

The most widespread electric drive fan, providing ample opportunities for regulation.

Typical cooling system controls are a coolant temperature sensor, the electronic unit controls and various actuators.

The coolant temperature sensor captures the value of the controlled parameter and converts it into an electrical signal. To expand the functions of the cooling system (exhaust gas cooling in the exhaust gas recirculation system, fan control, etc.), an additional coolant temperature sensor is installed at the radiator outlet.

The signals from the sensor are received by the electronic control unit and converted into control actions on the actuators. As a rule, an engine control unit with the appropriate software installed is used.

The following actuators can be used in the operation of the control system: thermostat heater, relay additional pump coolant, radiator fan control unit, engine cooling after shutdown relay.

The principle of operation of the cooling system

The operation of the cooling system is provided by the engine management system. IN modern engines the algorithm of work is implemented on the basis of mathematical model, which takes into account various parameters (coolant temperature, oil temperature, outdoor temperature etc.) and sets the optimal conditions for switching on and the operating time of structural elements.

The coolant in the system has forced circulation, which is provided by a centrifugal pump. The movement of fluid is carried out through the "cooling jacket" of the engine. In this case, the engine is cooled and the coolant is heated. The direction of fluid movement in the "cooling jacket" can be longitudinal (from the first cylinder to the last) or transverse (from the exhaust manifold to the intake).

Depending on the temperature, the liquid circulates in a small or large circle. When starting the engine, the engine itself and the coolant in it are cold. To speed up the engine warm-up, the coolant moves in a small circle, bypassing the radiator. The thermostat is closed.

As the coolant heats up, the thermostat opens and the coolant moves in a large circle - through the radiator. The heated liquid passes through the radiator, where it is cooled by the oncoming air flow. If necessary, the liquid is cooled by air flow from the fan.

After cooling, the liquid again enters the "cooling jacket" of the engine. During the operation of the engine, the cycle of movement of the coolant is repeated many times.

On turbocharged vehicles, a dual-circuit cooling system can be used, in which one circuit is responsible for cooling the engine, the other for cooling the charge air.