To protect the engine from overheating, thereby increasing the period of trouble-free operation of the car, an effective cooling system is needed. The upcoming study is devoted to "air vents", their device, as well as advantages and disadvantages. After reviewing the information provided, forced air cooling can be compared with liquid cooling to make right choice systems.

What is attractive air-cooled engine

In a functioning engine, the temperature of the cylinders can reach 2000 degrees, while 80-90 degrees is considered optimally acceptable. Of course, in such extreme conditions no part will last long. To preserve the working fragments of the car, the engine needs enough reliable system cooling. Such structures are of two types:

1. air-cooled system. Here, air acts as protection for the operating unit from overheating;
2. liquid cooling earlier, in the old days, was carried out plain water. Technical progress was reflected in the creation of a special substance called antifreeze. Antifreeze is also used to reduce the temperature of the motor.

IN this publication the first type of systems that protect a functioning engine from excessive overheating is considered in detail. This will allow an ignorant motorist to get acquainted with the device and the principle of operation of a complex technological mechanism.

Functions of cooling systems

It should be noted that maintaining the optimum temperature in the car engine requires protection not only from excessive overheating, but also from freezing. Subcooling of the unit can cause condensation fuel-air mixture caused by the contact of fuel with the cool surface of the cylinders.

Getting into the crankcase power plant, it leads to liquefaction lubricant, which is reflected in the loss of most of its useful characteristics.

Mixing fuel with oil causes an annoying drop in engine power. functional important details engines wear out faster. Also negative moment is the thickening of the oil in a supercooled unit. Deterioration in the timely supply of lubricant to the cylinders leads to exorbitant waste of fuel, the functional ability of the engine is significantly reduced.

In addition to performing the main function, cooling systems additionally provide:

• lowering the temperature of exhaust gases in the recirculation system;
• ventilation and air conditioning in the car. They are also responsible for heating;
• timely cooling of engine oil;
• maintenance of optimal temperature balance in turbocompressor units;
• cooling of the working fluid filling the automatic box.

Purpose and principle of operation of the air cooling system

It has been established that an overheating engine causes exorbitant fuel consumption, a large amount of machine oil. Parts important for the normal functioning of the car quickly fail due to rapid wear. In addition, a violation of the temperature regime can lead to an unreasonable loss of the required power by the motor.

With the help of an air cooling system, the optimum temperature is maintained in the engine. Also, its purpose is to control the heating of the air in the car. She keeps track of timely cooling lubricants, reduces the temperature of the working fluid filling the automatic box, and sometimes maintains optimal mode V throttle assembly and receiving manifold.

The principle of operation of the system is to remove heat by air flow from excessively heated parts of a running engine. In this way, the cylinders, block heads and oil cooler are cooled.

The air flow to the engine is forced by aluminum fan blades, protected by a special mesh from unwanted ingress of random objects that can damage the unit. Deflectors evenly distribute the air entering through the cooling fins between all parts of a functioning motor.

Fan design

It should be noted that forced air cooling is impossible without special device. The fan, which is a necessary link in the system under consideration, consists of the following parts:

• guiding diffuser, equipped around the circumference with stationary, radially arranged blades of variable cross section, affecting the uniform distribution of the air flow;
• a rotor having eight special blades placed along the radius;
• aluminum blades forcing air flow in the required direction;
• a casing that prevents the ingress of heat from the outside;
• a protective mesh that protects the mechanism from accidental penetration of foreign objects into the device.

The diffuser blades change the direction of the air flow, and it rushes in the direction opposite to the rotation of the rotor. This increases atmospheric pressure, causing better cooling engine.

Advantages and disadvantages of the engine air cooling system

Separately, it should be noted that sometimes natural circulation of atmospheric flows is quite enough to ensure a normal temperature regime. The outer surface of the cylinders of mopeds, motorcycles, piston and other simple engines is equipped with special ribs that contribute to the transfer of heat to the external environment.

Complex design car motor requires forced cooling. The air flow must be given a certain direction. Fans are used for this purpose.

Air-cooled engines have the following advantages:

1. extreme simplicity of design, which greatly simplifies the process of repairing or replacing parts that have become unusable;
2. relatively small weight;
3. solid reliability;
4. acceptable cost;
5. good cold start characteristics.

However, before choosing a car with an air-cooled engine, you should also familiarize yourself with the shortcomings of the systems in question. They are characterized by:

1. exorbitant noise that is created by a running fan;
2. increasing the size of the engine due to the need extra space to accommodate the blowing device;
3. uneven direction of air flows, which determines the possibility of local overheating;
4. excessive sensitivity to the quality of fuel, lubricants, as well as increased requirements for the condition of spare parts.

However, air cooling has found its niche in the automotive industry. Trucks, agricultural machinery and vehicles with diesel internal combustion engines are equipped with such motors.

Common myths about "air vents", true or fiction

Unfortunately, the shortcomings of "Zaporozhets" finally undermined the confidence of domestic motorists in the air engine cooling system. She was accused of strong heating, insufficient power and rapid failure. While the German "Beetle", equipped similar system, enjoys constant popularity among consumers, delighting the manufacturer with constant increased demand.

Based on the characteristics of the German car, let's examine in detail some of the fairly common legends that haunt air-cooled engines.

Statement 1. "Air" loses to a liquid system due to strong heating

It is by no means an indisputable truth. In fact, temperature features, on the contrary, can be considered an advantage of an engine cooled air flow. Of course, the reduced thermal conductivity does not allow the air to remove heat at a sufficient rate provided by water or antifreeze.

However, the temperature difference on the surface of the cylinders and during external environment much more difference between the walls and the fluid moving inside the system. Therefore, weather conditions affect the thermal regime of the "vent" to a lesser extent. The possibility of overheating a liquid-cooled motor in the heat is much higher.

Statement 2. Large dimensions

Also highly controversial. When comparing the dimensions of two engines having equal cylinder diameters and the same piston stroke, but equipped with different systems cooling, the advantage is often on the side of the "vent".

Despite the rather impressive appearance of a fan with a deflector and rather bulky casings surrounding the cylinders with heads, its parameters are somewhat more compact than those of a liquid unit.

In addition, the "dropsy" occupies a much larger space due to additional equipment carried outside the engine. On the body is a very bulky radiator, equipped with a fan. Also, a large number of various hoses does not add compactness at all.

Statement 3. Air systems lose to liquid systems in reliability

Not true. Statistical studies claim that in one in five cases of engine failure, the fault lies with liquid cooling. The reason is fail-safe parts like a thermostat, radiator, pump, etc.

The simplicity of the design ensures the reliability of the fan with a deflector, due to the low probability of breakage. In addition, an attractive point that testifies in favor of the "air vent" is the reduction in system maintenance costs.

Claim 4: Air cooling is too loud

Unfortunately, it is true. Design features air system does not provide effective sound-absorbing devices, which are available liquid engine. In addition, the ribs of the cylinders and heads of the "air vent" sometimes, on the contrary, amplify the noise produced by the functioning motor.

The designers have provided soundproofing of the liquid system, carried out thanks to the double walls of the cooling jacket, inside which antifreeze or water circulates. Therefore, in this position, the “air vent” really turned out to be a loser.

Proposition 5: Air motors wear out faster

Correct for legacy systems. The fan simply forced air flows onto the fins of the cylinders, without providing sufficient uniformity of airflow. Modern engines are characterized by rational heat distribution.

In addition, the higher temperature on the cylinder walls of the "air vents" helps to reduce losses caused by the friction of the rings on the cylinders due to better dilution of the lubricants. This explains the less wear on parts. The oil is less subject to oxidation, which slows down its aging, allowing you to save on frequent replacements.

Statement 6. Insufficient power

Not quite right. The reason for this accusation is the deterioration of the weight filling of the cylinders. working fluid causing a short drop in engine power. This is due to the increase in temperature of the cylinders and heads with increasing load, which leads to undesirable heating of the air inside the system.

However, at more revolutions the difference in the filling ratio at air engines and liquid motors becomes less than 3.5%, established by research, practically tending to zero. Therefore, you can fight the loss of recoil by increasing the speed.

Conclusion

So, the conducted research proved that air cooling is no worse than liquid cooling, and in some parameters even surpasses it. Isn't it time for manufacturers to think about resuming the production of cars with air systems? Consumer demand will grow, despite the sad experience of the ill-fated Zaporozhets.

Cooling system

The cooling system is designed to maintain the normal thermal regime of the engine.

When the engine is running, the temperature in the engine cylinders periodically rises above 2000 degrees, and the average temperature is 800-900°C!

If you do not remove heat from the engine, then in a few tens of seconds after starting it will no longer be cold, but hopelessly hot. Next time you can run your cold engine only after it overhaul.

The cooling system is necessary to remove heat from the mechanisms and parts of the engine, but this is only half of its purpose, however, more than half.

To ensure a normal working process, it is also important to accelerate the warm-up of a cold engine. And this is the second part of the cooling system.

As a rule, liquid cooling systems are used on cars, closed type, With forced circulation liquid and expansion tank (Fig. 29).

The cooling system consists of:

cooling jackets for the block and cylinder head,

centrifugal pump,

thermostat,

radiator with expansion tank

fan,

connecting pipes and hoses.

On fig. 29 you can easily distinguish two circles of coolant circulation.

Rice. 29. Scheme of the engine cooling system: 1 - radiator; 2 - pipe for circulation of the coolant; 3 - expansion tank; 4 - thermostat; 5 - water pump; 6 - cooling jacket of the cylinder block; 7 - cooling jacket of the head of the block; 8 - heater radiator with electric fan; 9 - heater radiator valve; 10 – plug for draining the coolant from the block; 11 - plug for draining the coolant from the radiator; 12 - fan

The small circle of circulation (red arrows) serves to warm up a cold engine as soon as possible. And when blue arrows join the red arrows, the already heated liquid begins to circulate in a large circle, cooling in the radiator. Leading this process automatic device – thermostat.

To control the operation of the cooling system, there is a coolant temperature gauge on the instrument panel (see Fig. 67). normal temperature coolant during engine operation should be in the range of 80–90 ° С.

Engine cooling jacket consists of many channels in the block and cylinder head through which coolant circulates.

Centrifugal pump causes the liquid to move through the engine cooling jacket and the entire system. The pump is driven by a belt drive from a pulley crankshaft engine. The belt tension is regulated by the deviation of the generator housing (see Fig. 63 a) or tension roller drive camshaft engine (see Fig. 11 b).

Thermostat designed to maintain a constant optimum thermal regime of the engine. When starting a cold engine, the thermostat is closed, and all the liquid circulates only in a small circle (Fig. 29 a) to warm it up as soon as possible. When the temperature in the cooling system rises above 80–85°C, the thermostat opens automatically and part of the liquid enters the radiator for cooling. At high temperatures, the thermostat opens completely, and now all the hot liquid is directed in a large circle for its active cooling.

Radiator serves to cool the fluid passing through it due to the air flow that is created when the car is moving or with the help of a fan. The radiator has many tubes and baffles, forming a large cooling surface area.

Expansion tank necessary to compensate for changes in the volume and pressure of the coolant during its heating and cooling.

Fan It is designed to forcefully increase the air flow passing through the radiator of a moving car, as well as to create an air flow in the case when the car is stationary with the engine running.

Two types of fans are used: permanently on, with a belt drive from the crankshaft pulley and an electric fan that turns on automatically when the coolant temperature reaches approximately 100 ° C.

Branch pipes and hoses are used to connect the cooling jacket to the thermostat, pump, radiator and expansion tank.

Also included in the engine cooling system interior heater. Hot coolant flows through heater radiator and heats the air that enters the car.

The air temperature in the cabin is regulated by a special crane, with which the driver increases or decreases the flow of fluid passing through the heater core.

The main malfunctions of the cooling system

Coolant leakage may appear as a result of damage to the radiator, hoses, gaskets and seals.

To eliminate the malfunction, it is necessary to tighten the hose and tube clamps, and replace the damaged parts with new ones. In case of damage to the radiator tubes, you can try to patch holes and cracks, but, as a rule, everything ends with the replacement of the radiator.

Engine overheating happens due to insufficient level coolant, loose fan belt tension, clogged radiator tubes, or a malfunctioning thermostat.

To eliminate engine overheating, restore the liquid level in the cooling system, adjust the fan belt tension, flush the radiator, and replace the thermostat.

Often, engine overheating also occurs with serviceable elements of the cooling system, when the car moves with low speed And heavy loads on the engine. This happens when driving in heavy road conditions, such as country roads and all the annoying city "traffic jams". In these cases, it is worth thinking about the engine of your car, and about yourself too, arranging periodic, at least short-term "breathes".

Be careful while driving and avoid emergency mode engine work! Remember that even a single overheating of the engine breaks the structure of the metal, while the life expectancy of the "heart" of the car is significantly reduced.

Operation of the cooling system

When operating the car, you should periodically look under the hood. A timely noticed malfunction in the cooling system will allow you to avoid engine overhaul.

If coolant level in expansion tank dropped or there is no liquid at all, then first you need to add it, and then you should figure out (on your own or with the help of a specialist) where it has gone.

During engine operation, the liquid heats up to a temperature close to the boiling point. This means that the water that is part of the coolant will gradually evaporate.

If in six months daily operation the level in the tank has dropped slightly, this is normal. But if yesterday there was a full tank, and today it is only at the bottom, then you need to look for a place where the coolant leaks.

Leakage of fluid from the system can be easily identified by dark spots on the asphalt or snow after a more or less long parking. Opening the hood, you can easily find the leak by comparing wet marks on the pavement with the location of the elements of the cooling system under the hood.

The fluid level in the tank must be checked at least once a week. If the level has dropped noticeably, then it is necessary to determine and eliminate the cause of its decrease. In other words, the cooling system must be put in order, otherwise the engine may become seriously "ill" and require "hospitalization".

Virtually all domestic cars as a coolant, a special low-freezing liquid with the name Tosol A-40. Number 40 indicates the negative temperature at which the liquid begins to freeze (crystallize). In the conditions of the Far North, it is used Tosol A-65, and, accordingly, it begins to freeze at a temperature of minus 65 ° C.

Antifreeze is a mixture of water with ethylene glycol and additives. Such a solution combines a lot of advantages. Firstly, it begins to freeze only after the driver himself has already frozen (just kidding), and secondly, Antifreeze has anti-corrosion, anti-foaming properties and practically does not form deposits in the form of ordinary scale, since it contains pure distilled water . That's why Only distilled water can be added to the cooling system.

When operating a vehicle, control not only the tension, but also the condition of the water pump drive belt, since its breakage on the road is always unpleasant. It is recommended to have a spare belt in the travel kit. If not yourself, then one of the good people will help you change it.

The coolant can boil and cause engine damage if the fan motor sensor. If the electric fan has not received a command to turn on, then the liquid continues to heat up, approaching the boiling point, without any cooling assistance.

But the driver has a device with an arrow and a red sector in front of his eyes! Moreover, almost always when the fan is turned on, a slight additional noise is felt. There would be a desire to control, but there will always be ways.

If on the way (and more often in a traffic jam) you notice that the temperature of the coolant is approaching the critical one, and the fan is running, then in this case there is a way out. It is necessary to include an additional radiator in the operation of the cooling system - the interior heater radiator. Fully open the heater tap, turn on the heater fan at full speed, lower the door windows and "sweat" to the house or to the nearest car service. But at the same time, continue to carefully monitor the arrow of the engine temperature gauge. If she still enters the red zone, stop immediately, open the hood and "cool down".

May cause trouble over time thermostat, if it ceases to let liquid through a large circle of circulation. Determining if the thermostat is working is not difficult. The radiator should not heat up (determined by hand) until the pointer of the coolant temperature gauge reaches the middle position (the thermostat is closed). Later, hot liquid will begin to flow into the radiator, quickly heating it up, which indicates the timely opening of the thermostat valve. If the radiator continues to be cold, then there are two ways. Knock on the thermostat housing, maybe it will still open, or immediately, mentally and financially, prepare to replace it.

"Surrender" to the mechanic immediately if oil dipstick you will see droplets of liquid that have entered the lubrication system from the cooling system. It means that damaged cylinder head gasket and coolant seeps into the engine sump. If you continue to operate the engine with oil half consisting of Tosol, then the wear of engine parts becomes catastrophic.

Water pump bearing does not break "suddenly". First, a specific whistling sound will appear from under the hood, and if the driver "thinks about the future", then he will replace the bearing in a timely manner. Otherwise, it will still have to be changed, but with the consequence of being late for the airport or for a business meeting, due to a “suddenly” broken car.

Every driver should know and remember that on a hot engine, the cooling system is in a state of overpressure!

If the engine of your car overheated and "boiled", then, of course, you need to stop and open the hood of the car, but you can not open the cap of the radiator or expansion tank. To speed up the process of cooling the engine, this will practically do nothing, and you can get severe burns.

Everyone knows what a clumsily opened bottle of champagne turns out to be for smartly dressed guests. In the car, everything is much more serious. If you quickly and thoughtlessly open the cork of a hot radiator, then a fountain will fly out from there, but not wine, but boiling Antifreeze! In this case, not only the driver, but also pedestrians who are nearby can suffer. Therefore, if you ever have to open the cap of a radiator or expansion tank, then you should first take precautions and do it slowly.

Radiator, fan, water pump, thermostat, cooling jacket, temperature sensor and pipes.

2. The main technical parameters of the components and assemblies of the cooling system, ensuring the operability of the system.

The cooling capacity of the radiator, the performance of the fan and the water pump, the opening and closing temperatures of the thermostat valve, the cooling capacity of the cooling jacket, the performance of the temperature sensor, the tightness of all elements of the system,

3. Reasons for the change technical parameters, both elements of the system, and it as a whole.

Scale in the cooling jacket and in the radiator, malfunction of the thermostat and temperature sensor, failure of the fan and water pump, system leakage, clogging of the radiator and cooling jacket.

4. Diagnostic signs and their parameters.

Overheating or hypothermia of the engine, temperature difference in the lower and upper tank of the radiator, slow or rapid heating of the engine at start-up, temperature of opening and closing of the thermostat, leakage of coolant.

5. Maintenance and repair

Flushing the system and descaling, replacing faulty nodes and unit, etc.

When burning working mixture in the engine cylinders, the gas temperature reaches 2500°C, and on average, when the engine is running, it is 800 ... 900°C. This causes severe heating of the parts and can lead to seizure of the pistons in the cylinder, burning of the valve heads, burning out of the lubricant, melting of the bearing shells and other malfunctions. To prevent this, it is necessary to maintain a certain thermal temperature in the engine, which is provided by the cooling system, which serves to remove excess heat from heated parts. In the cooling system, the temperature of the coolant at all engine operating modes must be maintained within 80 ... 100 ° C. All domestic cars use closed-type liquid cooling systems that communicate with the atmosphere through special valves at a certain excess pressure or vacuum. The circulation of the coolant is carried out forcibly by means of a liquid pump. To compensate for changes in the volume of the coolant during its heating and cooling, the system has an expansion tank.

General arrangement and principle of operation of a liquid cooling system

The main elements of this system are: a cooling jacket, a centrifugal coolant pump, pipelines, a radiator, a fan, an expansion tank, a thermostat, a sensor with a coolant temperature indicator.

The thermostat is used to accelerate the warm-up of the engine after starting and automatically maintain the optimal engine mode when driving.

When starting a cold engine, the thermocouple element of the thermostat is in the extreme position, in which the main valve is closed and the bypass valve is open. When the engine is running, the impeller of the centrifugal pump, driven through a belt drive from the crankshaft pulley, captures the coolant from the pipe and pumps it into the jacket of the block and the engine cylinder head. In this case, the liquid takes away excess heat from the heated parts, heats up itself and, through the open bypass valve of the thermostat, will again flow to the pump, i.e., the circulation will occur in a small circle, bypassing the radiator, which accelerates the heating of the engine. As the engine warms up, the thermocouple element of the thermostat heats up and moves the valves, gradually closing the bypass valve and opening the main valve. In this case, the circulation of the liquid will occur as before in a small circle and at the same time partially in a large circle through the radiator. When the engine is fully warmed up and the liquid temperature reaches 85 ... 95 ° C, the bypass valve will close completely, and the main one will open and the liquid will circulate only in a large circle in the following sequence: from the pump impeller to the block jacket and the cylinder head, through the pipe into the upper tank of the radiator, through the core (through the tubes) into the lower tank. The liquid cooled by the fan circulates through the pipe, through the open thermostat valve, through the pipe back to the pump, maintaining the required thermal conditions of the engine. The expansion tank is used to compensate for changes in the volume of liquid that occur when it is heated and cooled during engine operation and after it stops.

TO category:

The device and operation of the engine

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Purpose and principle of operation of the cooling system

The cooling system serves to forcibly remove heat from the engine cylinders and transfer it to the surrounding air. The need for a cooling system is caused by the fact that engine parts that come into contact with hot gases become very hot during operation. If the internal parts of the engine are not cooled, then due to overheating, the lubricant layer between the parts may burn out and seizing of moving parts due to their excessive expansion.

The cooling system can be air or liquid.

With an air cooling system (Fig. 1, a), heat from the engine cylinders is transferred directly to the air blowing them. To do this, in order to increase the heat transfer surface on the cylinders and the head, cooling fins are made, which are made by casting. The cylinders are surrounded by a metal casing. Air cooling the engine is sucked through the formed air jacket with the help of a fan. The fan is driven by a belt drive from the crankshaft pulley.

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The air cooling system was used only on engines of low power. The advantage of such a system is the simplicity of the device, some reduction in engine weight and ease of maintenance. For’more powerful engines the use of an air cooling system encounters a number of difficulties due to the need to remove a large amount of heat and ensure uniform cooling of all heating points of the engine.

The liquid cooling system with forced circulation of liquid includes water jackets, respectively, of the head and block, a radiator, lower and upper connecting pipes with hoses, a water pump with a water distribution pipe, a fan and a thermostat.

The water jackets of the head and block, pipes and radiator are filled with water. When the engine is running, the water pump driven by it creates a circular circulation of water through water jacket, pipes and radiator. Through the water distribution pipe, water is first directed to the most heated places in the unit. Passing through the water jacket of the block and head, water washes the walls of the cylinders and combustion chambers and cools the engine. The heated water enters the radiator through the upper pipe, where, branching through the tubes into thin streams, it is cooled by air,

which is sucked between the tubes by the rotating blades of the fan. The cooled water re-enters the water jacket of the engine.

In some engines with overhead valves, water from the pump is forcibly directed only to the head jacket, seats and nozzles exhaust valves, and then through the outlet pipe it is discharged to the radiator. In this case, the cylinders are cooled by water circulating in its jacket due to the presence of a difference in water temperatures in the water jacket of the block and head. More heated water from the water jacket of the block is displaced by colder water coming from the water jacket of the head, than natural convection water circulation (thermosiphon) is provided. With such cooling, the operating conditions of the engine cylinders improve.

A thermostat installed in the upper water pipe regulates the circulation of water through the radiator, maintaining its most favorable temperature.

V-shaped carbureted engines a common water pump, connected by a lower branch pipe to a radiator and mounted on the same shaft with a fan, pumps water through two branch pipes and water distribution channels into the water jackets of both sections of the block. Heated water is removed from the heads through channels, usually cast in top cover block, and through a common thermostat and the upper pipe goes back to the radiator. On diesel engines, the layout of the elements of the cooling system is somewhat modified.

Depending on the way the cavity of the cooling system is connected to the atmosphere, the forced cooling system is divided into two types - open and closed. In an open system, the cavity of the upper radiator tank is constantly in communication with the atmosphere. In a closed cooling system, which has been used on all cars, the reservoir cavity can communicate with the atmosphere only through a special vapor-air valve.

Rice. 1. Schemes of engine cooling systems

TO category:

Cars and tractors

General arrangement and operation of the liquid cooling system

The cooling system is designed to forcefully remove excess heat from engine parts and transfer it to the surrounding air. This creates a certain temperature regime, at which the engine does not overheat and does not overcool. Heat in engines is removed in two ways: liquid (liquid cooling system) or air ( air system cooling). These systems absorb 25-35% of the heat released during fuel combustion. The temperature of the coolant in the cylinder head should be 80-95 °C. This temperature regime is the most beneficial, ensures the normal operation of the engine and should not change depending on the ambient temperature and engine load. The temperature during the engine operating cycle varies from 80-120 °C (minimum) at the end of the intake to 2000-2200 °C (maximum) at the end of the combustion of the mixture.

If the engine is not cooled, then the gases having high temperature, the engine parts are very hot and they expand. The oil on the cylinders and pistons burns out, their friction and wear increase, and from excessive expansion of parts, the pistons in the engine cylinders jam, and the engine may fail. To avoid negative phenomena caused by overheating of the engine, it must be cooled.

However, excessive cooling of the engine adversely affects its operation. When the engine is overcooled, fuel vapors (gasoline) condense on the walls of the cylinders, washing away the lubricant, diluting the oil in the crankcase. Under these conditions, intense wear occurs piston rings, cylinder pistons and reduced efficiency and engine power. normal operation cooling system contributes to obtaining highest power, reducing fuel consumption and increasing the life of the engine without repair.

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Most engines have liquid cooling systems (open or closed). With an open cooling system inner space communicates directly with the surrounding atmosphere. Closed cooling systems have become widespread, in which the internal space only periodically communicates with environment with special valves. In these cooling systems, the boiling point of the coolant rises and the boiling point decreases.

Rice. 1. Scheme of the liquid cooling system: 1 - radiator; 2 - upper tank; 3 - radiator cap; 4 - control tube; 5 - upper radiator pipe; 6 and 19 - rubber hoses; 7 - bypass channel; 8 to 18 - outlet and inlet pipes, respectively; 9 - thermostat; 10 - hole; 11 - block head; 12 - water distribution pipe; 13 - liquid temperature indicator sensor; 14 - cylinder block; 15 and 21 - drain taps; 16 - water jacket; 17 - impeller of a water centrifugal pump; 20 - lower radiator pipe: 22 - lower radiator tank; 23 - fan drive belt; 24 - fan

The engines of GAZ-24 Volga, GAZ-bZA, ZIL-130, MA3-5335 and KamAZ-5320 vehicles have a closed liquid cooling system with forced circulation of liquid created by a water centrifugal pump. Fluid system cooling car engine(Fig. 1) consists of a water jacket, a radiator, a fan, a thermostat, a pump with an impeller, an outlet and an inlet pipe, a fan drive belt, a liquid temperature indicator sensor, drain taps and other parts. There is a double-walled space (water jacket) around the engine cylinders and the block head where the coolant circulates.

During engine operation, the coolant heats up and is supplied to the radiator by a water pump, where it is cooled, and then again enters the cylinder block jacket. For reliable operation engine, it is necessary that the coolant constantly circulates in a vicious circle: engine - radiator-engine. The liquid can circulate in a small circle, bypassing the radiator (cold engine, thermostat closed), or in a large circle, entering the radiator (warm engine, thermostat open). The direction of movement of the coolant is shown in fig. 42 arrows.

The engine water jacket consists of a cylinder block jacket and a block head jacket, interconnected by holes in the gasket between the head and the block. The impeller of the water centrifugal pump and the fan are driven by a V-belt. When the pump impeller rotates, the coolant is forced into the water distribution tube located in the head of the block. Through the holes in the tube, the liquid is directed to the exhaust valves, due to which the most heated parts of the head and cylinders are cooled. The heated coolant flows into the upper outlet pipe. If the thermostat is closed, then the liquid again flows through the bypass channel to the centrifugal pump. When the thermostat is open, the coolant flows into the upper radiator tank, cools, flowing through the tubes, and enters the lower radiator tank. The liquid cooled in the radiator is supplied to the pump through the lower inlet pipe.

The water jacket of the ZIL-130 car engine is connected to the radiator with flexible hoses. The upper tank of the radiator is connected to the inlet pipe jacket, and the lower tank is connected to the inlet pipe of the water pump. The left and right rows of cylinders are connected to the pump by two pipelines. A thermostat is installed in the pipe through which the heated coolant is supplied to the upper tank of the radiator. The compressor water jacket is permanently connected to the engine cooling system by flexible hoses. The radiator 18 of the heater is connected to the engine cooling system with hoses] the heater is turned on by a crane.

When starting, warming up and running the engine, while the temperature of the water in the cooling system is below 73 ° C, the liquid circulates through the water jackets of the block, block heads and compressor, but does not enter the radiator, since the thermostat is closed. Coolant is supplied to the water pump (regardless of the position of the thermostat valve) through the bypass hose from the inlet pipe jacket, from the compressor and from the heater radiator (if it is turned on).

Rice. 2. The cooling system of the car engine ZIL - 303 1 - radiator; 2 - blinds; 3 - fan; 4 - water pump; 5 and 27 - respectively, the upper and lower radiator tanks; 6 - radiator cap; 7 - outlet hose; 8 - compressor; 9 - inlet hose; 10 - bypass hose; 11 - thermostat; 12 - branch pipe; 13 - flange for installing a carburetor; 14 - inlet pipeline; 15 - heater valve; 16 and 17 - inlet and outlet tubes, respectively; 18 - heater radiator; 19 - liquid temperature indicator sensor; 20 - dosing insert; 21 - water jacket of the block head; 22 - water jacket of the cylinder block; 23 - drain valve of the cylinder block jacket; 24 - drain cock drive handle; 25 - drain valve of the radiator pipe; 26 = inlet

The water pump pumps fluid into the system, and its main flow passes through the water jacket of the cylinder block from its front to the rear. Washing the cylinder liners from all sides and passing through the holes in the mating surfaces of the cylinder block and block heads, as well as in the gasket located between them, the coolant enters the head jackets. At the same time, a significant amount of coolant is supplied to the most heated places - exhaust valve pipes and spark plug sockets. In the heads of the block, the coolant moves in the longitudinal direction from the rear end to the front due to the presence of holes of the appropriate diameter drilled in the mating surfaces of the cylinder block and heads, and metering inserts installed in the rear channels of the inlet pipeline. The hole in the insert limits the amount of fluid entering the intake manifold jacket. Warm liquid passing through the intake manifold jacket heats up combustible mixture coming from the carburetor (through the internal channels of the pipeline), and improves mixture formation.

Before starting work, it is necessary to check the liquid level in the radiator, since if it is insufficient, the circulation of the liquid is disturbed and the engine overheats. The refrigeration system must be filled with clean, soft water that does not contain lime salts. When using hard water, a large amount of scale is deposited in the radiator and water jacket, leading to overheating of the engine and a decrease in its power. Frequent water changes in the cooling system cause increased scale formation. Water can be softened in the following ways: boiling, adding chemicals to water, and magnetically treating it. It has been established that, passing through a weak magnetic force field, water acquires new properties: it loses its ability to form scale and dissolves the previously formed scale that was in the engine cooling system.

Water is poured into the cooling system through the radiator neck, which is closed with a stopper (Fig. 43). To drain water from the cooling system, taps located at the lowest points of the cooling system are used.

The diesel cooling system of the KAMAZ-5320 is designed for permanent use liquids TOCOL-A-40 or TOCOL-A-65 (freezing at low temperature). The use of water in the cooling system is allowed only in special cases and for a short time. The cooling system includes water jackets of the block and cylinder heads, a water pump, a radiator, a fan with a fluid coupling, blinds, two thermostats, an expansion tank, connecting pipes, hoses, V-belt transmission pump drives, drain cocks or plugs, coolant temperature sensors and other parts.

The plant allows the engine to operate at a coolant temperature not exceeding 105 °C. The temperature regime of the engine is maintained by two thermostats, a hydraulic clutch for turning on the fan and blinds. If the engine is not warmed up, then the coolant supplied by the pump enters the left row of cylinders and through the discharge pipe into the right row. It washes the outer surfaces of the cylinder liners of both rows, then through the holes in the upper plane of the cylinder block, the head gasket enters the cylinder heads, cooling the most heated places - exhaust channels and injector sockets. The heated liquid passes from the cylinder heads to the right and left pipes located in the "collapse" of the engine, then it is fed through the connecting pipe to the water distribution box (or thermostat box). The thermostat valves are closed, and the coolant is again supplied to the water pump through the bypass pipe 6.

Rice. 3. The cooling system of the diesel engine of the KaMAE-5320 car: 1 - crankshaft pulley; 2 - lower tank; 3 - blinds; 4 - radiator; 5 - fluid coupling of the fan drive; 6 - bypass pipe; 7 - discharge pipe; c - upper tank; 9 - upper branch pipe; 10 - thermostat; 11 - water distribution box; 12 - connecting pipe; 13 - inlet tube; 14 - right water pipe; 15 - outlet tube; 16 - intake manifold; 17 - sensor control lamp liquid overheating; 18 - expansion tank; 19 - neck with a sealing plug; 20 - plug with valves; 21 - outlet pipe from the compressor; 22 - outlet tube of the left water pipe; 23 - compressor; 24 - left water pipe; 25 - head cover; 26 - cylinder head; 27 - water pump; 28 - drain cock or plug; 29 - water pump pulley; 30 - fan; 31 - lower branch pipe

Thermostats are installed in a separate box, mounted on the front end of the right row of cylinders. The expansion tank is located on the engine with right side and is connected to the upper tank of the radiator, water distribution box, compressor and water jacket of the cylinder block. The expansion tank compensates for the change in the volume of liquid when it is heated, and allows you to control its level in the cooling system. Steam from the upper sections of the radiator and the system is discharged into the tank and condenses in it. The air collected in the tank improves the performance of the cooling system. TOCOJ1-A-40 or TOSOL-A-65 is poured into the cooling system through a neck having a sealed plug on the thread. Steam and air valves installed in a tube.

In the diesel cooling system, a fan drive fluid coupling is used, which transmits torque from the engine crankshaft to the fan. Using a fluid coupling, they maintain the most favorable temperature conditions in the cooling system and dampen the resulting fluctuations during a sharp change in the crankshaft speed. The fan drive fluid coupling has automatic control.

The fluid coupling is driven from the crankshaft of the engine through a splined drive shaft. Fan located coaxially with crankshaft, mounted on a hub mounted on the driven shaft. The leading part of the fluid coupling consists of: the drive shaft assembly with the casing; driving wheel, bolted to the casing and pulley shaft; pump and generator drive pulley bolted to the shaft. The leading part of the fluid coupling rotates on ball bearings. The driven part of the fluid coupling consists of: the driven wheel assembly, bolted to the driven shaft. The driven part of the fan drive fluid coupling rotates on ball bearings. The sealing of the hydraulic coupling is carried out by two sealing rings and self-clamping glands.

Rice. 4. Fan drive fluid coupling: 1 - front cover; 2 - body; 3 - casing; 4, 7, 13 and 20 - ball bearings; 5 - oil supply pipe; 6 - drive shaft; 8 - sealing rings; 9 - driven wheel; 10 - drive wheel; 11 - pulley; 12 - pulley shaft; 14 - thrust sleeve; 15 - fan hub; 16 - driven shaft; 17 and 21 t - self-clamping glands; 18 - gasket; 19 and 22 - bolts

To control the hydraulic clutch of the fan drive, there is a spool-type switch mounted on the discharge pipe at the front of the engine. Depending on the temperature of the liquid in the cooling system, the fluid coupling switch connects or disconnects the drive shaft from the driven one, changing the amount of oil entering the fluid coupling from the lubrication system. The oil for the operation of the hydraulic coupling is supplied by a pump into its cavity, then it is fed through the tube into the channels of the drive shaft and through the holes in the driven wheel into the interblade space. When the drive wheel rotates, the oil from its blades passes to the blades of the driven wheel, and it begins to rotate, transferring torque to the shaft and fan. Hydraulic coupling with the help of a crane Turns on or off, and in connection with this, the fan turns on or off. The valve is located in the hydraulic clutch switch housing.

The fan can operate in three modes:
- automatic - the temperature of the coolant in the engine is maintained at 80-95 ° C; the hydraulic clutch switch valve is set to position B (mark on the body); when the coolant temperature drops below 80 ° C, the fan automatically turns off;
- the fan is off - the valve of the hydraulic coupling switch is set to position 0; the fan can rotate at a low frequency;
- the fan is always on - in this mode, short-term operation is allowed in case of possible faults hydraulic clutch or its switch.

The temperature of the liquid in the cooling system is controlled by a remote thermometer, the receiver of which is located in the driver's cab on the instrument panel, and the sensor is in the water distribution box (diesel car KAMAZ-5320), in the water channel of the inlet pipeline (engines of GAZ-53A and ZIL-130 cars), in head of the block (engine of the car GAZ-24 "Volga"). If the temperature of the water in the cooling system exceeds a certain value, then on the instrument panel lights up signal lamp, for example, red (GAZ-63A car) at a water temperature of 105-108 ° C.

circuit diagram forced systems cooling modern engines is the same.

The ZIL-130 engine has a closed cooling system with forced fluid circulation. The system consists of a cooling jacket for the block and cylinder head, a radiator, connecting pipes, a water centrifugal pump, a fan, a thermostat, drain cocks for the cylinder block jacket and a radiator drain cock. The figure shows the cabin heater and windshield heater included in the cooling system (a. . The fluid is supplied to the heater through the pipeline, and the outlet is through the pipeline when the valve is open

When the engine is running, the water pump creates fluid circulation through the cooling jacket, pipes and radiator. Passing through the shirt of the block and head, the coolant washes the cylinder walls, combustion chambers and other parts. The heated liquid through the pipe enters the upper part of the radiator and further along a large number tubes from the top of the radiator to the bottom, while giving off heat to the air flow. The cooled liquid from the lower tank (reservoir) of the radiator again enters the engine jacket. The system is calculated so that when passing through the radiator, the temperature of the liquid drops by 6-10 °C. The thermostat, installed in the upper water pipe, automatically changes the intensity of fluid circulation through the radiator, maintaining its most favorable temperature. The air supply to the radiator can be controlled by means of blinds - curtains in front of the radiator, which are opened manually or automatically depending on the thermal regime of the engine.

On engines trucks ZIL, MAZ, KAMAZ installed compressor brake system, the cylinders of which are liquid-cooled, connected in parallel to the engine cooling system.

Monitoring the operation of the cooling system consists in checking the liquid level and observing the readings of a thermometer, consisting of a sensor and a receiver installed on the instrument panel.

Engine SMD -14 caterpillar tractor DT-75M has a closed cooling system with forced circulation of coolant. The cooling system includes: a centrifugal-type water pump with a fan, cooling jackets of the block and block heads driven by a V-belt; outlet pipe; radiator consisting of upper and lower cast cisterns, between which the core is soldered; liquid temperature indicator sensor; connecting pipes and hoses. To remove air from the system, a hole in the water pump housing is closed with a plug. Engine cooling system includes a cooling jacket starting motor. Fill the system with liquid through the radiator neck, and drain through the taps. The intensity of liquid cooling in the radiator is manually regulated by lifting the curtains located in front of the radiator to a greater or lesser height.

Rice. 5. Engine cooling system ZIL -130

The circulation of the coolant in the system is carried out by a water pump, which sucks the liquid from the lower radiator tank through the pipe and delivers it to the water distribution channel of the crankcase. Through the side holes in the water distribution channel, the liquid is supplied simultaneously to all cylinders. From the crankcase cooling jacket, the liquid enters the water jacket of the block head and then through three holes in the upper wall of the head into the drain pipe and then into the upper radiator tank. Part of the fluid from the crankcase through the connecting pipe enters the cylinder jacket of the starting engine, and from there through the head of its cylinder into the outlet pipe.

The capacity of the cooling system of autotractor engines is determined by the type of engine and is in the range of 7.5-50 liters.