Most of the serious car malfunctions are related to engine overheating. The temperature of gases in the cylinder reaches 2000 gr. When fuel is burned in the cylinder, a large amount of heat is generated, which must be removed and thereby prevent overheating of engine parts.
Principles of construction of cooling systems
The decrease in the efficiency of the cooling system leads to an increase in the temperature of the pistons, a decrease in the gaps between the piston and the cylinder. Thermal gaps are reduced to zero. The piston touches the cylinder walls, scuffing occurs, the overheated oil loses its lubricating properties and the oil film breaks. This mode of operation can lead to engine seizure. Overheating is accompanied by uneven expansion of the block head, mounting bolts, engine block, etc. In the future, engine destruction is inevitable: cracks in the block head, deformation of the junction planes of the head and the cylinder block itself, valve seat cracks, etc. - I even unpleasantly listed all this, so it’s better not to bring it to this!
The engine and oil cooling system is designed to prevent such a development of events, but in order for the system to cope with its tasks, it is necessary to use high-quality coolant (coolant). Low-freezing coolants are called antifreeze- from the English word "antifreeze". Previously, coolants were prepared on the basis of aqueous solutions of monohydric alcohols, glycols, glycerol, and inorganic salts. Currently, preference is given to monoethylene glycol - a colorless syrupy liquid with a density of approximately 1.112 g / cm2 and a boiling point of 198 g. The task of the coolant is not only to cool the engine, but also not to boil over the entire temperature range of the engine and its components, to have a high heat capacity and thermal conductivity, not to foam, not to have a harmful effect on pipes and seals, and to have lubricating and anti-corrosion properties.
In the 70s, antifreeze was produced based on an aqueous solution of monoethylene glycol with a crystallization onset temperature of 40 g. It did not require dilution with water when added to the cooling system. This drug is called TOSOL- by the name of the laboratory "Technology of Organic Synthesis". Because the name is not patented, then TOSOL is called a ready-to-use product, and “antifreeze” is a concentrated solution (although TOSOL is also antifreeze).
Ready-made antifreezes are dyed for safety and catchy colors are chosen: blue, green, red. During operation, antifreeze loses its useful properties - anti-corrosion properties decrease, and the tendency to foaming increases. The service life of domestic coolants is from 2 to 5 years, imported 5-7 years.
The figure below shows a diagram of a car's cooling system. There is nothing special or complicated in the cooling system, and yet ...
Rice. 1 - engine, 2 - radiator, 3 - heater, 4 - thermostat, 5 - expansion tank, 6 - radiator plug, 7 - upper pipe, 8 - lower pipe, 9 - radiator fan, 10 - fan switch on sensor, 11 - sensor temperature, 12 - pump.
When the engine is started, the pump (water pump) starts to rotate. The pump drive may have its own pulley driven by the accessory belt or driven by the rotation of the timing belt. In the cooling system there is an impeller, which rotates, sets the coolant in motion. To quickly warm up the engine, the system is "short-circuited", i.e. The thermostat is closed and does not let liquid into the cooling radiator. As the temperature of the coolant rises, the thermostat opens, putting the system in another state, when the coolant passes through a long path - through the radiator of the cooling system (the short path is blocked by the thermostat). Thermostats have different opening characteristics. The opening temperature is usually marked on the edge. Probably it is not necessary to explain the device of the radiator. At the bottom of the radiator is a fan switch sensor. If the coolant temperature reaches a certain value, the sensor will close, and since it is electrically connected to break the power supply circuit of the electric fan, then when it is closed, the cooling system fan should turn on. As the coolant cools, the fan turns off, and the thermostat closes the long path for a short one. It's simple, but not very...
Such a scheme is the basis, but life does not stand still and various manufacturers will improve cooling systems. On some cars, you will not find a sensor for turning on the cooling fan, because. The fan is turned on by the ECU by the engine, depending on the readings of the coolant temperature sensor. It is worth paying attention to the situation in which, when the ignition is wedged, the cooling system fan immediately turns on. Either the temperature sensor is faulty, or its circuits are damaged, or the engine ECU itself is faulty - it “does not see” the engine temperature and, just in case, immediately turns on the fan.
On some cars, on the way to the heater, special solenoid valves are installed that allow or block the path of the coolant (BMW, MERCEDES). Such valves sometimes "help" the cooling system fail.
Troubleshooting in the cooling system
The specialists of the company "AB-Engineering" under the leadership of Khrulev A.E. developed a table of causes and consequences of engine overheating. Myself engine overheating- this is the temperature regime of its operation, characterized by boiling of the coolant. But not only overheating is a malfunction. The operation of the engine at a constantly low temperature is also considered a malfunction, because. in this case, the engine operates at an unusual temperature regime. Failure of the thermostat, electric fan or viscous coupling, thermal switches, etc. will lead to abnormal operation of the cooling system. If the driver detects signs of a violation of the thermal regime of the engine in time and does not allow irreversible processes, then the repair of the cooling system will not be expensive and long. Therefore, we strongly recommend that you (and your customers) pay attention to the temperature regimes of the engine.
A. The first step is to check the connection diagram of the pipes of the cooling system, if the car is not new or has been repaired after repair at another service.
To some, such a proposal will seem ridiculous, but life has shown the opposite, examples:
- the car assembled after the overhaul had a connection between the pipe of the crankcase ventilation system and the expansion tank of the cooling system;
- an installed non-standard fan with blades directing the air flow in the wrong direction;
- the blades of the electric fan rotate freely on the shaft of the switched off engine;
- electric fan connectors are loose or broken, etc.
Inspect the radiator for external blockage. Inspect zones and ways of natural cooling of the engine. A negative example would be a powerful underbody protection that blocks the airflow that cools the engine from below. Sometimes a breakage of the bumper, the lower part of which has airflow guides to the engine, leads to overheating (VW Passat B3).
B. After inspection, it is necessary to check the level of coolant in the system, the presence and serviceability of the valves of the radiator caps and expansion tank, the integrity of the pipes and hoses. Clarify which antifreeze or just water is poured into the system, because. Each liquid has its own boiling point.
If the first two points (A or B) revealed any malfunctions, they must be eliminated or taken into account when making a “verdict”. When adding coolant, remember that not all vehicles are designed to be "just add water". For example, on a BMW car (M20, E34), when adding coolant, it is necessary to turn on the ignition and set the stove temperature regulators to the “maximum heat” mode so that the stove valves turn on and open for the movement of coolant through the system, in addition, it is necessary to raise the radiator up, because the expansion tank, built into the radiator by the "miracle designers" of Germany, is located below the level of the passenger compartment stove and it is often air-filled.
If there is a suspicion that the engine is air-filled (there is air in the system that prevents the movement of fluid), it is necessary to unscrew the special plugs of the cooling system to release air. They are usually located at the top of the engine cooling system. Start the engine, turn on the interior heaters, turn on the fan. Observe the warming up of the engine, components and assemblies. If there is an expansion tank in the system, then check the fluid circulation, i.e. its movement through the system. When adding engine speed up to 2,500 - 3,000, a powerful jet of coolant should flow into the tank. Air can escape from the unscrewed (not completely!) Plugs for some time, and as soon as the liquid flows, the plugs must be tightened. As the engine warms up, warm air should flow from the interior heater. If the engine is warming up and the air from the heater is cold, then this is the first sign of “airing” of the cooling system. It is necessary to turn off the engine and take measures to find and eliminate this malfunction.
With a working thermostat (the opening temperature can vary from 80 to 95 degrees), after warming up, the lower radiator pipe should have approximately the same temperature as the upper one. If this is not the case, then poor pumping of coolant through the radiator.
With a working thermostat, after a while after it opens, the cooling system fan should turn on. If not an electric fan is installed in the system, then it is necessary to check the sensor for switching on the electromagnetic clutch circuit or the operation of the viscous clutch. In the event of a malfunction of the viscous coupling, the cooling system fan on a warm engine can be stopped and held by hand (when stopping, be careful to stop with a soft object so as not to damage the fan impeller or hand). It is necessary to check the air pressure and its temperature - hot air should be directed to the engine.
The pressure in the cooling system should slowly increase as the engine warms up and slowly decrease after the engine is turned off. If the upper pipe leading to the radiator swells with an increase in engine speed, it is necessary to check whether some of the exhaust gases enter the cooling system. This is usually noticeable by an oil film in the expansion tank or bubbling coolant. At the same time, white smoke usually comes out of the muffler from the heated and evaporating coolant that enters the engine cylinders. In this case, it is necessary to check the engine oil filler neck and a white emulsion has settled on it, then the coolant is not only in the engine cylinders, but also in the lubrication system (it is necessary to stop moving). Here are a few examples from the practice of various services that “speak” that Engine diagnostics are inseparable from diagnostics of all vehicle systems, including the cooling system.
A \ m MAZDA 626 - the owner complains about uneven engine speed or increased idle speed. Checking the control system (and self-diagnosis) did not reveal any malfunctions. Pay attention to the increased voltage on the coolant temperature sensor.
The control system adds the amount of fuel as reacts to high voltage on the sensor (engine cold). It turned out that there is little liquid in the cooling system, the sensor is “bare”. Just add the coolant level to the normal level and the speed will return to normal.
A \ m FORD - the coolant entered the oil in an unconventional way - through the oil cooling system located around the oil filter.
A \ m FORD - after warming up the engine, one cylinder stopped working. Replacing the spark plug and other work led to a positive result (this had nothing to do with determining the malfunction, it was just that the engine cooled down during the work) - the cylinder began to work and the client left. The next day he was with us again. It turned out — a crack in the head of the block in the area of the exhaust valve of the inoperative cylinder. As long as the engine is cold everything is fine. When warmed up, the crack increased and began to let coolant into the cylinder. The mixture was depleted and interruptions in work began, and then the cylinder was completely turned off.
There are many such examples, they are in the practice of every car repairman. The main conclusion should be made by everyone who is seriously engaged in auto repair - to notice and analyze everything significant and insignificant, because. these positions can change places abruptly.
Reliable and trouble-free operation of the internal combustion engine (internal combustion engine) cannot be carried out without a cooling system. It is convenient to present its basic principles of operation in the form of a diagram of the engine cooling system. The main purpose of the system is to remove excess heat from the engine and. An additional function is the heating of the car with the interior heater stove. The device and the principle of operation shown in the diagram are approximately the same for different types of cars.
Scheme, elements of the cooling system and their work
The main elements that make up the engine cooling system circuit are found and are similar in different types of engines: injection, diesel and carburetor.
General scheme of the liquid engine cooling system
Liquid cooling of the motor makes it possible to equally take heat from all components and parts of the engine, regardless of the degree of thermal load. A water-cooled engine generates less noise than an air-cooled engine and has a faster warm-up rate at start-up.
The engine cooling system contains the following parts and elements:
- cooling jacket (water jacket);
- radiator;
- fan;
- liquid pump (pump);
- expansion tank;
- connecting pipes and drain taps;
- interior heater.
- The cooling jacket (“water jacket”) is considered to be the cavities that communicate between the double walls in those places where the removal of excess heat is most needed.
- Radiator. Designed to dissipate heat into the surrounding atmosphere. It structurally consists of many curved tubes with additional ribs to increase heat transfer.
- The fan, which is activated by an electromagnetic, less often by a hydraulic clutch, when the coolant temperature sensor is triggered, increases the air flow on the car. Fans with a “classic” (always on) belt drive are rare these days, mostly on older cars.
- The centrifugal liquid pump (pump) in the cooling system provides a constant circulation of the coolant. The pump drive is most often implemented using a belt or gear. Turbocharged engines with direct fuel injection are usually equipped with an additional pump.
- Thermostat - the main unit that regulates the flow of coolant, is usually installed between the radiator inlet pipe and the "water jacket", structurally made in the form of a bimetallic or electronic valve. The purpose of the thermostat is to maintain the specified operating temperature range of the coolant in all engine operating modes.
- The heater radiator is very similar to the smaller cooling system radiator and is located in the passenger compartment. The fundamental difference is that the heater radiator transfers heat to the passenger compartment, and the cooling system radiator to the environment.
Principle of operation
The principle of operation of liquid cooling of the engine is as follows: the cylinders are surrounded by a "water jacket" of coolant, which takes away excess heat and transfers it to the radiator, from where it is transferred to the atmosphere. The liquid, continuously circulating, ensures the optimum temperature of the engine.
The principle of operation of the engine cooling system
Coolants - antifreeze, antifreeze and water - during operation form sediment and scale, disrupting the normal operation of the entire system.
Water is not chemically pure in principle (with the exception of distilled water) - it contains impurities, salts and all kinds of aggressive compounds. At elevated temperatures, they precipitate and form scale.
Unlike water, antifreezes do not create scale, but decompose during operation, and the decay products adversely affect the operation of mechanisms: corrosion deposits and layers of organic substances appear on the internal surfaces of metal elements.
In addition, various foreign contaminants such as oil, detergents or dust can enter the cooling system. They can also get in, used for emergency repair of damage in radiators.
All these contaminants are deposited on the internal surfaces of components and assemblies. They are characterized by poor thermal conductivity and clog thin tubes and radiator cells, disrupting the efficient operation of the cooling system, which leads to engine overheating.
Video on how motor cooling works, the principle of operation and malfunctions
Something else useful for you:
flushing
Flushing the engine cooling system is a process that many drivers often neglect, which sooner or later can cause fatal consequences.
Signs it's time to flush
- If the arrow of the temperature gauge is not in the middle, but tends to the red zone while driving;
- It is cold in the cabin, the heating stove does not provide sufficient temperature;
- Radiator fan turns on too often
It is impossible to flush the cooling system with plain water, since contaminants are concentrated in the system, which are not removed even by water heated to high temperatures.
Scale is removed with acid, and fats and organic compounds are removed exclusively with alkali, while both compositions cannot be poured into the radiator at the same time, since, according to the laws of chemistry, they neutralize each other. Manufacturers of flushing products, trying to solve this problem, have created a number of products that can be roughly divided into:
- alkaline;
- acid;
- neutral;
- two-component.
The first two are too aggressive and are almost never used in their pure form, as they are dangerous for the cooling system and require neutralization after use. Less common are two-component types of cleaners containing both solutions - alkaline and acidic, which are poured alternately.
The greatest demand is for neutral cleaners that do not contain strong alkalis and acids. These products have varying degrees of effectiveness and can be used both for prevention and for major flushing of the engine cooling system from severe contamination.
Flushing the cooling system
Flushing the cooling system
- Antifreeze, antifreeze or water is drained. Before this, you need to start the engine for a couple of minutes.
- Fill the system with water and cleaner.
- Turn on the engine for 5-30 minutes (depending on the brand of cleaner) and turn on the interior heating.
- After the time indicated in the instructions, the engine must be turned off.
- Drain the used cleaner.
- Rinse with water or a special compound.
- Top up with fresh coolant.
Flushing the cooling system is simple and affordable: even inexperienced car owners can perform them. This operation significantly extends the engine life and maintains its performance at a high level.
Faults
There are a number of the most common malfunctions in the engine cooling system:
- Airing the engine cooling system: remove the air lock.
- Insufficient pump performance: replace the pump. Select a pump with a maximum impeller height.
- Faulty thermostat: eliminated by replacing with a new device.
- Low performance of the coolant radiator: flushing the old one or replacing the standard one with a model with higher heat dissipation qualities.
- Insufficient performance level of the main fan: Install a new fan with a higher performance.
Video - identifying malfunctions of the cooling system in a car service
Regular care, timely replacement of the coolant guarantees long-term operation of the car as a whole.
When fuel is burned inside the cylinder, the temperature of the gases rises to 2000°C. Heat is spent on mechanical work, partially carried away with exhaust gases, 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 transferred to work 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 |
21 - right radiator tank |
|---|
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 at the signal of the electronic engine control unit (on the 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 monitor 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.
The coolant pump is a vane, centrifugal type, driven from the crankshaft pulley by a timing belt. 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 (the intake manifold is not heated).
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. The on-board control system also reports a drop in the liquid level; for this, a sensor is provided in the reservoir 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, in cars it contains up to 8 ... 12 liters of liquid, in trucks with a gasoline carburetor engine - up to 30 liters, and in trucks with a diesel engine - up to 50 liters. Antifreeze containing anti-corrosion and anti-foaming 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.).
The cooling system of an internal combustion engine is designed to remove excess heat from engine parts and assemblies. In fact, this system is bad for your pocket. Approximately one third of the heat obtained from the combustion of precious fuel has to be dissipated in the environment. But such is the structure of a modern internal combustion engine. The ideal would be an engine that can operate without removing heat to the environment, and turn all of it into useful work. But the materials used in modern engine building cannot withstand such temperatures. Therefore, at least two main, basic parts of the engine - the cylinder block and the block head - have to be additionally cooled. At the dawn of the automotive industry, two cooling systems appeared and competed for a long time: liquid and air. But the air cooling system gradually lost ground and is now used mainly on very small motor vehicle engines and low power generator sets. Therefore, let's take a closer look at the liquid cooling system.
Cooling system device
The cooling system of a modern automobile engine includes an engine cooling jacket, a coolant pump, a thermostat, connecting hoses, and a radiator with a fan. The heater heat exchanger is connected to the cooling system. In some engines, the coolant is also used to heat the throttle assembly. Also, in engines with a pressurization system, coolant is supplied to liquid-air intercoolers or to the turbocharger itself to reduce its temperature.
The cooling system works quite simply. After starting a cold engine, the coolant begins to circulate in a small circle with the help of a pump. It passes through the cooling jacket of the block and cylinder head of the engine and returns to the pump through the bypass (bypass) pipes. In parallel (on the vast majority of modern cars), the liquid constantly circulates through the heater heat exchanger. As soon as the temperature reaches the set value, usually around 80-90 ˚С, the thermostat starts to open. Its main valve directs the flow to the radiator, where the liquid is cooled by the oncoming air flow. If there is not enough airflow, then the cooling system fan comes into operation, in most cases it has an electric drive. The movement of liquid in all other nodes of the cooling system continues. Often the exception is the bypass channel, but it does not close on all vehicles.
The schemes of cooling systems in recent years have become very similar to each other. But two fundamental differences remain. The first is the location of the thermostat before and after the radiator (in the direction of the liquid). The second difference is the use of a pressurized circulating expansion tank, or an unpressurized expansion tank, which is a simple reserve volume.
Using the example of three schemes of cooling systems, we will show the difference between these options.
Components
Shirt head and cylinder block are channels cast in an aluminum or cast iron product. The channels are sealed, and the joint between the block and the cylinder head is sealed with a gasket.
coolant pump bladed, centrifugal type. Driven by either a timing belt or an accessory drive belt.
Thermostat is an automatic valve that operates when a certain temperature is reached. It opens, and part of the hot liquid is discharged into the radiator, where it cools. Recently, electronic control of this simple device has been used. The coolant began to be heated with a special heating element for earlier opening of the thermostat if necessary.
Fluid change and flush
If you didn’t have to replace any node in the cooling system earlier, then the instructions recommend changing antifreeze at least every 5–10 years. If you did not have to add water to the system from a canister, and even worse - from a roadside ditch, then when changing the fluid, the system can not be flushed.
But if the car has seen a lot in its lifetime, then when replacing the fluid it is useful to produce. Having opened the system in several places, you can thoroughly rinse it with a jet of water from a hose. Or just drain the old liquid and pour clean, boiled water. Start the engine and warm up to operating temperature. After waiting until the system cools down, so as not to burn yourself, drain the water. Then blow air through the system and fill in fresh antifreeze.
Flushing the cooling system is usually started in two cases: when the engine overheats (this manifests itself primarily in the summer) and when the stove stops heating in winter. In the first case, the reason lies in the radiator tubes overgrown with dirt from the outside and clogged from the inside. In the second, the problem is that the heater radiator tubes are clogged with deposits. Therefore, during a planned fluid change and when replacing components of the cooling system, do not miss the opportunity to thoroughly flush all the nodes.
Tell us what kind of cooling system problems you encountered. And wish you a hot heater in winter and good cooling in summer.
The working processes of an automobile engine take place at high temperatures, therefore, to ensure its performance for a long time, it is necessary to remove excess heat. This function is provided by the cooling system (CO). In the cold season, due to this heat, the passenger compartment is heated.
In turbocharged vehicles, the function of the cooling system is to lower the temperature of the air supplied to the combustion chamber. Additionally, in one of the circles from the cooling system of some car models equipped with an automatic transmission (automatic transmission), oil cooling in the automatic transmission is switched on.
Two main types of CO are installed in cars: water and air. The principle of operation of the water-cooled engine cooling system is to heat the liquid from the power plant or other components and release this heat to the atmosphere through the radiator. The air system uses air as the working coolant. Both options have their advantages and disadvantages.
However, the cooling system with liquid circulation has become more widespread.
Air CO
air cooling
The main advantages of this arrangement include the simplicity of design and maintenance of the system. Such CO practically does not increase the mass of the power unit, and is also not capricious to changes in ambient temperature. The negatives include a significant power take-off of the motor by the fan drive, increased noise during operation, poorly balanced heat removal from individual components, the impossibility of using a block engine system, the impossibility of accumulating the removed heat for further use, for example, interior heating.
Liquid CO
liquid cooling
The system with the use of heat removal with the help of a special fluid, due to its design, can effectively remove excess heat from mechanisms and individual parts of the structure. Unlike air, the device of the engine cooling system with liquid contributes to a faster set of operating temperatures at start-up. Also, motors with antifreeze run much quieter and are less prone to detonation.
Elements of the cooling system
Let's take a closer look at how the engine cooling system works on modern cars. There are no significant differences between gasoline and diesel engines in this regard.
The structural cavities of the cylinder block act as a “shirt” for cooling the engine. They are located around areas from which heat is required to be removed. For faster drainage, a radiator is installed, consisting of curved copper or aluminum tubes. A large number of additional fins accelerate the heat transfer process. Such ribs increase the cooling plane.
A fan is placed in front of the radiator. The influx of colder flows begins after the closing of the electromagnetic clutch. It turns on when the fixed temperature values are reached.
Thermostat operation
The continuity of the circulation of the coolant is ensured by the operation of the centrifugal pump. The belt or gear drive for it receives rotation from the power plant.
The thermostat regulates the flow directions.
If the temperature of the coolant is not high, then the circulation takes place in a small circle, without including a radiator in it. If the permissible thermal regime is exceeded, then the thermostat starts the flow in a large circle with the participation of the radiator.
For closed hydraulic systems, the use of expansion tanks is common. Such a tank is also provided in the CO of the car.
coolant circulation
The interior is heated using the heater core. Warm air in this case does not escape into the atmosphere, but is launched into the car, creating comfort for the driver and passengers in the cold season. For greater efficiency, such an element is installed almost at the fluid outlet from the cylinder block.
The driver receives information about the state of the cooling system using a temperature sensor. Signals also go to the control unit. He can independently connect or turn off actuators to maintain balance in the system.
System operation
Antifreezes with many additives, including anti-corrosion ones, are used as coolants. They help to increase the durability of components and parts used in CO. Such a liquid is forcibly pumped through the system by a centrifugal pump. The movement begins from the cylinder block, the hottest point.
At first, there is a movement in a small circle with a closed thermostat without entering the radiator, because even the operating temperature for the motor has not yet been reached. After entering the operating mode, circulation occurs in a large circle, where the radiator can be cooled by a counter flow or using a connected fan. After that, the liquid returns to the "shirt" around the cylinder block.
There are cars using two cooling circuits.
The first lowers the temperature of the motor, and the second takes care of the charge air, cooling it to form a fuel mixture.
