The engine is almost identical on all machines. Modern cars use a hybrid system. Yes, it is, because not only liquid, but also air is involved in cooling. They blow the radiator cells. Due to this, cooling is much more efficient. It is no secret that at low speeds, the circulation of the liquid does not save - you have to additionally install a fan on the radiator.

radiator fan

Let's talk about domestic cars, for example, about the Lada. To ensure better heat transfer, the engine cooling system ("Kalina"), the circuit of which has a standard configuration, contains a fan. Its main function is to blow air into the radiator cells when the liquid reaches a critical temperature. Operation is controlled by a sensor. On domestic cars, it is installed at the bottom of the radiator. In other words, there is a liquid that has given off heat to the atmosphere. And it should have a temperature of 85-90 degrees at this point of the contour. If this value is exceeded, it is necessary to carry out additional cooling, otherwise boiling water will enter the engine jacket. Consequently, the operation of the motor will occur at critical temperatures.

Cooling radiator

It serves to release heat into the atmosphere. The liquid passes through the cells, which have narrow channels. All these cells are connected by thin plates that improve heat transfer. When moving at high speed, the air passes between the cells and contributes to the rapid achievement of the result. This element contains any schema cooling systems engine. Volkswagen, for example, is no exception.

Above was considered a fan that is mounted on a radiator. It blows air when the critical temperature is reached. To improve the efficiency of the element, it is necessary to monitor the cleanliness of the radiator. Its cells are clogged with debris, heat transfer is deteriorating. Air does not pass well through the cells, heat is not released. The result - the temperature of the engine rises, its operation is disturbed.

System thermostat

It is nothing more than a valve. It reacts to temperature changes in the cooling circuit. More about them will be discussed below. The scheme of the UAZ engine cooling system is based on the use of a high-quality thermostat, which is made of a bimetallic plate. Under the action of temperature, this plate is deformed. You can compare it with a circuit breaker used in the power supply of houses and enterprises. The only difference is that it is not the switch contacts that are controlled, but the valve that supplies hot liquid to the circuits. The design also has a return spring. When the bimetallic plate cools down, it returns to its original position. And the spring helps her to return.

Sensors used in refrigeration

Only two sensors are involved in the work. One is mounted on the radiator, and the second - in the jacket of the engine block. Let's go back to domestic cars and remember the Volga. The engine cooling system circuit (405) also has two sensors. Moreover, the one that is located on the radiator has a simpler design. It is also based on a bimetallic element, which deforms with increasing temperature. This sensor turns on the electric fan.

On cars of the classic VAZ series, a direct fan drive was previously used. The impeller was installed directly on the axis of the pump. The rotation of the fan was made constantly, regardless of the temperature in the system. The second sensor, installed in the engine jacket, serves one purpose - transmitting a signal to the temperature indicator in the cabin.

Liquid pump

Let's go back to the Volga. The cooling system, the circuit of which contains a circulation liquid pump, cannot simply function without it. If you do not give the fluid movement, then it will not be able to move along the contours. Consequently, stagnation will appear, the antifreeze will begin to boil, and the motor may jam.

The design of the liquid pump is very simple - an aluminum housing, a rotor, a drive pulley on one side and a plastic impeller on the other. Installation is made either inside the engine block or outside. In the first case, the drive is carried out, as a rule, from the timing belt. For example, on VAZ cars, starting from model 2108. In the second case, the drive is carried out from a pulley

Stove outline

Some cars made decades ago had air-cooled engines. There is only one inconvenience in this case: I had to use a gasoline stove, which “ate” a lot of fuel. But if liquid circuits of engine cooling systems are used, you can take hot antifreeze, which is supplied to the radiator. Thanks to the stove fan, hot air is supplied to the cabin.

In all cars, the stove radiator is mounted under the instrument panel. First, an electric fan is installed, then a radiator is installed on it, and air ducts fit on top. They are necessary for the distribution of hot air throughout the cabin. In new cars, its distribution is controlled by microprocessor systems and stepper motors. They open or close the dampers depending on the temperature in the cabin.

Expansion tank

Everyone knows that any liquid expands when heated - increases in volume. So it needs to go somewhere. But on the other hand, when the liquid cools, its volume decreases, therefore, it must be added to the system again. It is impossible to do this manually, but with the help of an expansion tank, this procedure can be automated.

Most modern cars schemes of sealed type engine cooling systems are used. For these purposes, there is a plug on the expansion tank with two valves: one for the inlet, the second for the outlet. This allows the pressure in the system to be close to one atmosphere. With a decrease in its indicator, air is sucked in, with an increase, it is discharged.

Branch pipes of cooling systems

When fuel is burned inside the cylinder, the temperature of the gases rises to 2000°C. Heat is spent on mechanical work, is partially carried away with exhaust gases, is spent on radiation and heating of engine parts. If it is not cooled, then it loses power (filling of the cylinders with the working mixture worsens, premature self-ignition of the mixture occurs, etc.), wear of parts increases (oil burns out in the gaps) and the likelihood of their breakdown increases as a result of a decrease in the mechanical properties of materials.

If the engine is supercooled, the amount of heat that goes into operation decreases, the fuel condenses on the cold walls of the cylinders, flows into the crankcase (oil reservoir) and dilutes the lubricant, which also leads to increased wear of rubbing parts and a decrease in engine power. Thus, maintaining a certain thermal regime of the engine is an important and mandatory matter. Therefore, all car engines have a cooling system.

There are liquid and air cooling systems. Liquid cooling systems have become more widespread, since with their help a more favorable thermal regime for engine parts is created, the possibility of manufacturing engine parts from relatively inexpensive materials. Such engines during operation create less noise due to the presence of double walls (shirts) and a layer of coolant.

1 - heater radiator 2 - heater radiator steam outlet hose 3 - outlet hose 4 - supply hose 5 - coolant temperature sensor (in the block head) 6 - pump inlet pipe hose 7 - thermostat 8 - filling hose 9 - cork expansion tank 10 - coolant level indicator sensor 11 - expansion tank 12 - outlet pipe 13 - liquid chamber of the carburetor starting device 14 - radiator outlet hose 15 - radiator inlet hose 16 - radiator steam outlet hose 17 - left radiator tank 18 - sensor for turning on the electric fan 19 - fan motor 20 - electric fan impeller

21 - right radiator tank 22 - drain plug 23 - electric fan casing 24 - toothed timing belt 25 - impeller of the coolant pump 26 - inlet pipe of the coolant pump 27 - supply hose to the liquid chamber of the carburetor starter 28 - outlet hose 27 - hose for supplying coolant to the throttle pipe 28 - coolant outlet hose from the throttle pipe 29 - coolant temperature sensor in the outlet pipe 30 - radiator tubes 31 - radiator core

Cooling system - liquid, closed type, with forced circulation. The tightness of the system is ensured by inlet and outlet valves in the plug of the expansion tank. The exhaust valve maintains an increased (compared to atmospheric) pressure in the system on a hot engine (due to this, the boiling point of the liquid becomes higher, steam losses decrease). It opens at a pressure of 1.1-1.5 kgf/cm2. The inlet valve opens when the pressure in the system drops by 0.03-0.13 kgf / cm2 relative to atmospheric pressure (on a cooling engine).

The thermal mode of operation of the engine is maintained by a thermostat and an electric radiator fan. The latter is turned on by a sensor screwed into the left radiator tank (on the VAZ-2110 engine) or through a relay on a signal electronic block engine control (on VAZ-2111, -2112 engines). Sensor contacts are closed at a temperature of 99±2°C, and open at a temperature of 94±2°C.

To control the temperature of the coolant, a sensor is screwed into the cylinder head of the engine, connected to the temperature gauge on the dashboard. An additional temperature sensor is installed in the outlet pipe of injection engines (VAZ-2111, -2112), which provides information for the electronic engine control unit.

Coolant pump - vane, centrifugal type, driven by a pulley crankshaft toothed timing belt drive. Pump body - aluminum. The roller rotates in a double-row bearing with a "lifetime" supply of grease. The outer ring of the bearing is locked with a screw. A toothed pulley is pressed onto the front end of the roller, and an impeller is pressed onto the rear end. A thrust ring made of a graphite-containing composition is pressed against the end face of the impeller, under which there is an oil seal. If the pump fails, it is recommended to replace it as an assembly.

The redistribution of fluid flows is controlled by a thermostat. On a cold engine, the thermostat bypass valve closes the pipe leading to the radiator, and the liquid circulates only in a small circle (through the thermostat bypass pipe), bypassing the radiator. On the VAZ-2110 engine, the small circle includes a heater radiator, an intake manifold, a carburetor heating unit and a liquid chamber of a semi-automatic starting device. On VAZ-2111, -2112 engines, liquid, except for the heater, is supplied to the throttle assembly heating unit (heating intake manifold not provided).

At a temperature of 87±2°C, the bypass valve of the thermostat begins to move, opening the main pipe; in this case, part of the liquid circulates in a large circle, through the radiator. At a temperature of about 102 ° C, the nozzle opens completely, and all the liquid circulates in a large circle. The stroke of the main valve must be at least 8 mm.

The VAZ-2112 engine thermostat has an increased resistance of the bypass valve (throttle hole), due to which the fluid flow through the heater radiator increases.

The coolant is poured into the system through the expansion tank. It is made of translucent polyethylene, which allows you to visually control the liquid level. Onboard system control also reports a drop in the liquid level; for this, a sensor is provided in the tank lid. Two steam pipes are also connected to the tank: one - from the heater radiator, the other - from the engine cooling radiator.

The radiator consists of two vertical plastic tanks (left - with a baffle) and two horizontal rows of round aluminum tubes with pressed cooling plates. To increase the cooling efficiency, the plates are stamped with a notch. The tubes are connected to the tanks through a rubber gasket. Fluid enters through the top port and exits through the bottom port. Next to the inlet pipe is a thin branch pipe of the steam pipe.

The capacity of the liquid cooling system depends on the size and degree of forcing (for example, compression ratio) of the engine and averages 0.2..0.3 liters per horsepower. Therefore, cars it contains up to 8 ... 12 liters of liquid, trucks with petrol carbureted engine- up to 30 l, and for trucks with diesel engine- up to 50 l. Antifreeze containing anti-corrosion and anti-foam additives, as well as additives that exclude the formation of scale, antifreeze brand A-40 or A-65 has a thickening temperature, respectively - 40 and - 65 ° C. When the engine is running, the liquid washing its cylinders and head heats up and opens an automatic valve (thermostat) located in the pipeline connecting the engine to the radiator. The pump, driven by the crankshaft, circulates fluid in the system. Hot fluid, passing through the radiator tubes, gives off heat to the air supplied to it by the fan. The intensity of engine cooling can be changed by changing the intensity of fluid circulation or the intensity of the air flow passing through the radiator, depending on the ambient air temperature or driving conditions (speed, load, etc.).

As noted earlier, there are two types of engine cooling systems - liquid and air. They are distinguished by a thermal circuit and a coolant, which ensures the removal of heat from the most heated parts. The main components of the types of cooling systems are shown in fig. 1.7. Depending on the type of cooling system, they can have a different design.

In liquid cooling systems, the coolant circulates through the "cooling jacket - radiator" circuit. The heat transfer fluid heats up due to the temperature difference between the cylinder walls and the heat transfer fluid. Heated coolant

Rice. 1.7.

transfers heat to the heat sink, where it is partially dissipated into the environment by the air flow passing through the heat sink. This process is continuous due to the constant circulation of the liquid. Heat removal is forced and regulated.

Liquid cooling systems can be flow, evaporative and closed.

Flow cooling systems coolant (water) is taken from natural reservoirs, sent to the engine cooling jacket and, after heating, thrown into the reservoir (Fig. 1.8). These systems are simple in design, their effectiveness depends on the quality and temperature of the water. They are used in stationary, marine and outboard engines.

Rice. 1.8.

In flow-through cooling systems, the temperature of the water leaving the engine is about 85 °C. The temperature difference between the water leaving the engine and entering it does not exceed

15...20 °С. It is accepted that when cooling with hard fresh and sea water, the temperature at the engine outlet should not exceed 55 ° C in order to avoid intensive scale and salt release on the internal cavities of the cooling systems. This drawback in marine engines is partially eliminated through the use of flow-closed cooling systems.

A flow-closed cooling system consists of two liquid circuits, one of which is closed, using fresh non-rigid water, the other is flow-through, using water from a reservoir (Fig. 1.9). The closed circuit water from the engine cooling jacket is cooled in a cooler, water circulation is forced and provided by a water pump. Water from the reservoir is supplied to the refrigerator by the second pump, which cools the water of the closed circuit. An expansion tank is provided in the closed cooling circuit to compensate for the increase in water volume during heating, to remove air from the water and to compensate for water leaks from the system.

The temperature of the water leaving the engine in closed systems communicating with the atmosphere does not rise above 85...90 °C. When equipping the expansion tank with a steam-air valve -

Rice. 1.9. The scheme of the combined flow-closed cooling system pom pressure in the system exceeds atmospheric and is 0.12 ... 0.13 MPa, the water temperature rises to 105 ° C.

Rice. 1.10.

The difference in water temperature at the outlet of the engine and the inlet after the refrigerator should be no more than 10 ... 15 °.

Evaporative cooling systems(Fig. 1.10) provide heat removal due to the evaporation of the coolant (water), washing the most heated parts of the engine. The released vapors condense in the cooler of the cooling system. Water circulation occurs due to the movement of liquid layers during the formation and movement of the vapor fraction. Evaporative cooling systems are simple in design and require large amounts of water due to evaporation. Evaporation systems are used mainly on stationary high power kalorizatorpy engines with a low degree of compression and ignition of the working mixture from the incandescent (calorificator) head.

A closed cooling system with natural circulation of the coolant is the ter mine background of the cooling system (Fig. 1.11). The circulation of the liquid is carried out due to the pressure that occurs at different densities of the heated and cooled liquid. The coolant in the cavities around the cylinders and in the head during engine operation heats up, rises and enters the upper radiator tank. In the radiator, the liquid under the action of gravitational forces descends into the lower tank. The air flow, which, under the influence of the fan, passes through the core of the radiator, cools the liquid. From the lower tank of the radiator, the cooled liquid enters the engine cooling jacket, displacing the heated layers of liquid into the upper tank of the radiator.

The thermosyphon-solid cooling system has an uncomplicated device, less energy-intensive, but works satisfactorily

Rice. 1.11.

cooling

with a large volume of liquid and a significant cooling surface of the radiator. The temperature difference between the coolant at the engine outlet and at the inlet after the radiator reaches 30 °C. On tractors and automobiles, the thermosyphon cooling system is not used due to the large size and mass parameters, unregulated ™ and large temperature difference of the coolant.

The forced circulation cooling system (Fig. 1.12) differs from the thermosyphon one in that a pump is installed after the radiator. The liquid from the lower reservoir is forced under pressure into the lower cavity of the cooling jacket, and then passes into the upper cavity and head

The circulation of liquid from the lower cavity of the cooling jacket to the upper one is a disadvantage of this system, since the liquid enters the combustion chamber zone and the surfaces of the head that have the highest temperature already heated. Such circulation of the coolant does not contribute to the efficient flow of the engine's working process.

The forced circulation cooling system can be either open or closed. The closed system is disconnected from the atmosphere and operates at excess pressure, as a result of which the boiling point when filling the system

Rice. 1.12.

liquids

water rises to 105 ... 107 ° C. The operating temperature of the cooling water in a closed system is 98...100 °C, and in an open system communicating with the atmosphere it is 90...95 °C.

The combined cooling system (Fig. 1.13) is characterized in that the coolant is pumped into the upper cavity of the cooling jacket by a pump. The water pump provides forced circulation of liquid. In the outlet pipe

Rice. 1.13.

a thermostat is installed, a channel (pipe) is made from the thermostat installation cavity, connected to the suction cavity of the water pump. When the engine warms up, the thermostat directs the liquid, bypassing the radiator, to the pump, which ensures intensive heating of the engine. After reaching operating temperature in the cooling system, the thermostat valve opens and directs fluid through the radiator. An excess pressure of 0.045...0.05 MPa is maintained in the cooling system, as a result of which the boiling point of water rises to 107...110 °C, which reduces the likelihood of its boiling under increased load conditions.

Fluid temperature difference at the engine outlet and after the radiator is 5...6 °C, which provides favorable conditions for engine operation. Combined closed systems with forced circulation and automatic control of the liquid temperature are more economical than those previously considered and are widely used on tractors and automobiles.

air cooling systems, unlike liquid ones, they do not have a variety of schemes according to the principle of operation. The engine is cooled by air flow passing through the finned surface of the cylinder. External surfaces of the engine block air cooling have a casing, deflectors that form an air path. The air flow in the air path is directed to the hottest parts of the engine. The movement of the air flow can be carried out by injection or suction. Significant disadvantage The second way is that the finned surfaces are intensively polluted and the cooling efficiency decreases. The method of forcing air into the engine cooling air path has received the greatest application. The design of air-cooled circuits depends on the location and layout of the cylinders.

The air flow pattern is determined by the layout of the fan, its drive. The fan is driven directly from the crankshaft or by a belt drive. For efficient and uniform cooling of the engine at the lowest power consumption, air must blow over the surfaces of the cooling parts evenly and at a sufficiently high mass velocity. The air flow should initially cool the cylinder head, including the spark plugs and injectors.

Rice. 1.14.

On fig. 1.14 shows the layout diagrams of air-cooled engines with a vertical in-line arrangement of cylinders. The air flow is forced into the air path, which is formed along one of the sides of the engine cylinder bank.

The aerodynamic resistance of the air path depends on the installation location and the fan drive. When the fan is installed on the axis of the crankshaft, the trajectory of the movement of air particles lengthens, the air flow makes several turns before reaching the finned surface of the cylinders.

With a V-shaped arrangement of cylinders (Fig. 1.15), it is possible to use one or two blowers. The fan can be driven directly from the crankshaft or mounted to direct airflow to each bank of cylinders and be belt driven. With the opposite arrangement of the cylinders, the air flow is injected into the air path and enters each row of cylinders (Fig. 1.16).

Regardless of the cylinder layout, installation and fan drive, the principle of operation of the cooling system is unchanged. The main disadvantage of the air cooling system is uneven cooling and a higher temperature regime of the engine. The temperature of the inner surfaces of the cylinders and the head reaches 130...140 °C. The temperature in air cooling systems is maintained by means of devices that regulate the flow rate of air by moving it through the interfin channels of the cooling surfaces, and in other ways. Air cooling is widely used on small-sized, low-power engines; its use is limited on high-power engines.

Rice. 1.15.

(ICE) and their components are exposed to intense heat during the operation of various vehicles. At the same time, both overheating and hypothermia of the motor can provoke its failure. In this regard, one of the most important tasks for the developers of power units is to ensure the optimal thermal regime of their operation. A well-organized engine cooling system contributes to obtaining the best operating parameters ICE, which include:

1. Maximum power.
2. Minimum fuel consumption.
3. Extended service life.

The influence of temperature parameters on the operation of the motor

In one working cycle, the temperature in the internal combustion engine cylinders changes from 80 ... 120 degrees Celsius during the intake of a combustible mixture to 2000 ... 2200 degrees Celsius during its combustion. In this case, the power unit heats up quite strongly.

If the motor is not sufficiently cooled during operation, then its parts become very hot and change in size. Significantly decreases (due to burnout) and the volume of engine oil poured into the crankcase. As a result, friction between the interacting parts increases, which leads to their rapid wear or even jamming.

However, supercooling of the internal combustion engine adversely affects its operation. On the walls of the cylinders of a cold engine, fuel vapors condense, which, washing away the lubricant layer, dilute motor oil located in the crankcase.

To eliminate the negative consequences associated with violation of the thermal regime, cooling systems are designed in such a way as to exclude overheating and hypothermia of the motor during operation.

As a result, the chemical properties of the latter deteriorate, which contributes to:

• increased consumption of engine oil;
• intensive wear of rubbing surfaces;
• power drop power unit;
• increase in fuel consumption.

Classification

When the motor is running, it is necessary to ensure the removal of 25 to 35% of the generated heat. For its effective absorption (removal), water, air or special liquid(antifreeze, antifreeze). The coolant material determines the way the power unit is cooled.

There are systems:

1. Forced air cooling.
2. Liquid cooling with a closed cycle.

Liquid cooling system

At present, for efficient cooling automotive engines use a closed liquid cooling system with a closed cycle.

Design

Without fail, the system contains an expansion tank, which serves to compensate for changes in the volume of liquid when its temperature changes. In addition, a coolant is poured through it.

The system also includes:

• water jacket of the power unit (the space between the double walls of the cylinder block and its head in places where excessive heat is removed);
• temperature sensor;
• a bimetallic or electronic thermostat that provides the optimum temperature in the system;
• a centrifugal-type pump that provides forced circulation of the coolant in the system;
• a fan that increases the flow of oncoming air to the main radiator of the system;
• a radiator that transfers heat to the environment;
• heater radiator designed to transfer heat directly to the car interior;
• control device built into the dashboard of the car.

Operating principle

The coolant is poured into the system through the expansion tank. Constantly circulating inside the system, it removes heat from constituent parts of the motor, heated during operation, heats up, enters the radiator, is cooled in the radiator by the oncoming air flow and returns back.

If necessary, the fan turns on, increasing the cooling efficiency. For closed cooling systems, the coolant temperature should not exceed 126 degrees Celsius. Thus, the optimal thermal mode of operation of the power unit is ensured.

Additional functions

In addition to its main task - removing heat from heating elements, the liquid engine cooling system also provides:

• Warming up the power unit in the cold season

IN modern systems liquid cooling, there are two circuits through which coolant can circulate. This is done so that at the time of starting a cold engine, when its parts and the liquid itself have low temperature, the circulation of the coolant was carried out in a small circle (past the radiator).

This is provided by a thermostat, which, at the moment when the temperature rises to a certain level (70-80 degrees Celsius), opens, allowing the coolant to circulate in a large circle (through the radiator). Thus, an accelerated process of warming up the engine is carried out.

• Heating the air in the car

In the cold season, with the help of a hot coolant, the air in the car is heated. For this, an additional radiator is installed in the cabin and equipped with its own fan. With their help, the heat taken from the hot liquid is distributed throughout the cabin.

• Reducing the temperature of the air injected into the cylinders

Especially for engines equipped with turbochargers, two-circuit systems are provided, in which one circuit provides liquid cooling, and the second - air cooling.

In addition, the coolant cooling circuit is also double-circuit system, one circuit of which cools the cylinder head, and the other - the block itself.

This is due to the fact that in a turbocharged engine, the temperature of the cylinder head must be lower than the temperature of the block itself by 15 ... 20 degrees Celsius. A feature of such a cooling system is that each circuit is controlled by its own thermostat.

Advantages and disadvantages

Fluid system engine cooling is present in almost all modern cars. Fundamentally different from air-cooled systems, it guarantees:

• uniform and rapid heating of the power unit;
• efficient heat dissipation in any engine operating conditions;
• reduction of power costs;
• stable thermal mode of operation of the motor;
• the possibility of using the generated heat to heat the air in the cabin, etc.

Among the few disadvantages of a liquid cooling system are:

• need regular maintenance and the complexity of the repair;
• increased sensitivity to temperature changes.

Faults and solutions

All liquid cooling systems have characteristic faults. Most often found:

1. jamming of the thermostat in the closed position (liquid circulation is carried out in a small circle);
2. pump failure;
3. damage to the exhaust valve built into the plug of the expansion tank;
4. coolant leakage due to depressurization of the system (damage to seals, corrosion, etc.).
5. In addition, quite often the thermostat jams in the “Open” position (the coolant circulates in a large circle), which increases the warm-up time of a cold engine and contributes to the instability of the thermal regime during its further operation.

All these malfunctions are characterized by a significant increase in the operating temperature of the power unit, which can lead to boiling of the coolant and overheating of the motor.

All defects are eliminated by replacing faulty and / or damaged parts or components.

Air cooling system

Air-cooled motors were equipped with vehicles in the 50-70s of the last century. Typical representatives of such cars are Zaporozhets or FIAT 500. Now air-cooled engines are practically never found in the automotive industry.

Design and principle of operation

Structurally, the forced air cooling system is mounted in engine compartment vehicle and consists of:

• suction or blower fan;
• guide ribs of the engine cooling jacket;
• governing bodies ( throttle valves, controlling the air supply or a clutch that regulates the fan speed in automatic mode);
• temperature sensor installed in the power unit;
• control device, displayed on dashboard inside the car.

The motor is cooled by oncoming cold air. To enhance its flow, a blower type fan is most often used. It enhances the flow of cold dense air and ensures its supply in large quantities at low energy costs.

The suction fan requires a lot of power, but provides a more uniform heat removal from the parts of the power unit.

Advantages and disadvantages

Forced air-cooled motors are distinguished by:

• simplicity of design;
• low requirements for changes in ambient temperature;
• light weight;
• simple maintenance.

The disadvantages of the air cooling system include:

• a large loss of motor power, which is spent on ensuring the operation of the fan;
• high noise level during fan operation;
• insufficient cooling individual elements engine due to uneven airflow;
• the impossibility of using excess heat to heat the cabin.

In the car, it is designed to protect the working unit from overheating and thereby controls the performance of the entire engine block. Cooling is the most important function in the operation of the engine internal combustion.

The consequences of a malfunction in the cooling of the internal combustion engine can be fatal for the unit itself, up to the complete failure of the cylinder block. Damaged nodes may no longer be subject to restoration work, their maintainability will be equal to zero. It is necessary to treat the operation with all care and responsibility and carry out periodic flushing of the engine cooling system.

By controlling the cooling system, the car owner directly takes care of the "health of the heart" of his iron "horse".

Purpose of the cooling system

The temperature in the cylinder block when the unit is running can rise to 1900 ℃. Of this volume of heat, only a part is useful and is used in the required operating modes. The rest is taken out by the cooling system. engine compartment. Increase temperature regime beyond the norm is fraught negative consequences that lead to burning lubricants, violation of technical clearances between certain parts, especially in piston group which will reduce their service life. Overheating of the engine, as a result of a malfunction of the engine cooling system, is one of the reasons for the detonation of the combustible mixture supplied to the combustion chamber.

Engine overcooling is also undesirable. In a "cold" unit, there is a loss of power, the oil density increases, which increases the friction of non-lubricated components. working combustible mixture partially condenses, thereby depriving the cylinder walls of lubrication. However, the surface of the cylinder wall undergoes a corrosion process due to the formation of sulfur deposits.

The engine cooling system is designed to stabilize the thermal conditions necessary for the normal functioning of the vehicle's engine.

Types of cooling system

The engine cooling system is classified according to the method of heat removal:

• cooling with liquids in a closed type;
• air cooling in open type;
• combined (hybrid) heat removal system.

Currently, air cooling in cars is extremely rare. Liquid can be open type. In such systems, heat is removed through the steam pipe to the environment. A closed system is isolated from the outside atmosphere. Therefore, this type is much higher. At high pressure, the boiling threshold of the cooling element increases. The refrigerant temperature in a closed system can reach 120℃.

Air cooling

Natural forced air cooling is the most simplest way heat dissipation. Engines with this type of cooling emit heat into the environment using radiator fins located on the surface of the unit. Such a system has a huge lack of functionality. The fact is that this method directly depends on the small specific heat of air. In addition, there are problems with the uniformity of heat removal from the motor.

Such nuances prevent the installation of an efficient and compact installation at the same time. In the engine cooling system, air is supplied unevenly to all parts, and then the possibility of local overheating must be avoided. Following the design features, the cooling fins are mounted in those places of the engine where the air masses are the least active, due to aerodynamic properties. Those parts of the motor that are most susceptible to heat are placed towards the air masses, while the "colder" sections are placed at the back.

Forced air cooling

Motors with this type of heat dissipation are equipped with a fan and cooling fins. Such a set of structural units makes it possible to artificially inject air into the engine cooling system to blow the cooling fins. A protective casing is installed above the fan and fins, which participates in the direction of air masses for cooling and prevents heat from entering from the outside.

The positive aspects in this type of cooling are simplicity design features, light weight, lack of refrigerant supply and circulation units. The disadvantages are the high noise level of the system and the bulkiness of the device. Also, in forced air cooling, the problem with local overheating of the unit and diffuse airflow has not been solved, despite the installed casings.

This type of engine overheating warning was actively used until the 70s. The operation of the engine cooling system with forced air type has been popular on subcompact vehicles.

Cooling with liquids

The liquid cooling system is by far the most popular and widespread. The process of heat removal takes place with the help of a liquid refrigerant circulating through the main elements of the engine through special closed lines. The hybrid system combines the elements of air cooling at the same time as liquid. The liquid is cooled in a radiator with fins and a fan with a casing. Also, such a radiator is cooled by supply air masses when the vehicle is moving.

The liquid cooling system of the engine produces a minimum noise level during operation. This type collects heat everywhere and removes it from the engine with high efficiency.

According to the method of movement of the liquid refrigerant, the systems are classified:

Engine cooling system device

The liquid cooling design has the same structure and elements as for gasoline engine as well as for diesel. The system consists of:

• radiator block;
• oil cooler;
• fan, with shroud installed;
• pumps (pump with centrifugal force);
• a tank for expanding the heated liquid and level control;
• refrigerant circulation thermostat.

When flushing the engine cooling system, all these nodes (except for the fan) are affected for more efficient further work.

The coolant circulates through the lines inside the block. The totality of such passages is called the "cooling jacket". It covers the most heat-prone areas of the engine. The refrigerant, moving along it, absorbs heat and carries it to the radiator block. Cooling down, he repeats the circle.

System operation

One of the main elements in the device of the engine cooling system is the radiator. Its task is to cool the refrigerant. It consists of a radiator crate, inside which tubes are laid for the movement of fluid. The coolant enters the radiator through the lower pipe and exits through the upper one, which is mounted in the upper tank. On top of the tank there is a neck, closed with a lid with special valve. When the pressure in the engine cooling system increases, the valve opens slightly and the liquid enters the expansion tank, attached separately in the engine compartment.

Also on the radiator is a temperature sensor that signals the driver about the maximum heating of the liquid through a device installed in the cabin on the information panel. In most cases, a fan (sometimes two) with a casing is attached to the radiator. The fan is activated automatically when the critical temperature of the coolant is reached or it works forcibly from a drive with a pump.

The pump ensures constant circulation of coolant throughout the system. The pump receives rotational energy by means of a belt drive from the crankshaft pulley.

The thermostat controls the large and small circle of refrigerant circulation. When the engine is started for the first time, the thermostat circulates fluid in a small circle so that the engine unit warms up to operating temperature faster. The thermostat then opens big circle engine cooling systems.

antifreeze or water

Water or antifreeze is used as a coolant. Modern car owners are increasingly using the latter. Water freezes at sub-zero temperatures and is a catalyst in corrosion processes, which negatively affects the system. The only plus is its high heat dissipation and, perhaps, availability.

Antifreeze does not freeze in cold weather, prevents corrosion, prevents sulfur deposits in the engine cooling system. But it has a lower heat transfer, which negatively affects the hot season.

Faults

The consequences of a cooling failure are overheating or hypothermia of the engine. Overheating can be caused by insufficient fluid in the system, unstable job pump or fan. Also, the thermostat does not work properly when it should open a large cooling circle.

They can be caused by severe contamination of the radiator, slagging of lines, poor performance of the radiator cap, expansion tank, or poor-quality antifreeze.