Hover your mouse over the image to make it clickable.
Why you need an engine cooling system can already be guessed from the name - while working, the engine heats up and cools through the radiator. This is in short. In fact, the task of the engine cooling system is to maintain its temperature in a certain range (85-100 degrees), called the operating temperature. At operating temperature, the motor operates as efficiently and safely as possible.
Large and small circle cooling system
After starting, the engine should reach operating temperature. For this, it is divided into two parts - a small circle and a large circle of circulation. In a small circle, the coolant circulates as close as possible to the cylinders and, accordingly, heats up as quickly as possible. As soon as it warms up to the highest operating temperature, the valve opens and the fluid goes to a large circle, where it does not allow the engine to overheat. The task of the small circle is to maintain the operating temperature, and the large one is to remove excess heat.
The stove as part of the engine cooling system
It's nice when the interior warms up quickly, and this is because it is part of a small circle of circulation. Through the hoses, the liquid goes to the stove radiator and returns back. What does it mean? For the stove to start blowing warm air faster, it should be turned on when the engine warms up.
Coolant pump and thermostat
So, we found out that the engine does not overheat due to the coolant circulation. But what makes the liquid move? Answer - . This is such a special pump, which is driven by the engine through a belt, but there are pumps with an electric motor. The main pump malfunctions are associated with leakage through the drain hole and bearing wear (accompanied by squeaking). There are also pumps with a plastic impeller, which corrodes from quality antifreeze.
This is the same valve that opens when the coolant is heated and lets it go in a large circle. Consists of a cylinder with a substance that expands when heated; reaching a certain temperature, it squeezes out the stem and opens the valve. Cooling down, the stem retracts and the valve closes.
Radiator and expansion tank of the engine cooling system
It is part of a large circle and is installed in front of the car. A liquid circulates in it, which is cooled by oncoming air and a fan.
The fan works on suction so as not to interfere with the oncoming air flow.
The radiator cap maintains pressure in the cooling system. It has a valve that opens when the pressure exceeds the operating pressure, and bleeds excess fluid through the hose into the expansion tank.
Here How is the engine cooling system. Among the main problems associated with this system, it is worth highlighting.
Engine internal combustion(ICE) each vehicle undergoes significant stress during operation. To ensure it correct operation and the safety of individual mechanisms and their parts, an important point is sufficient cooling of the motor.
There are two main types of internal combustion engine cooling systems: air and liquid. Air type in modern automotive industry used only in sports cars, as an addition to liquid, since the benefit of air flow alone to ensure the normal operating temperature of the unit is negligible.
The first vehicles of the automaker ZAZ were equipped exclusively with air-cooled. Despite various engineering ideas, the Zaporozhets engines often overheated on hot summer days.
General picture of the cooling system
Regardless of what type of engine is installed in the car and what brand of car, the cooling system has a generally similar device. Ensuring normal operating temperature power unit achieved by circulating the coolant through the channels of the system. Thus, each internal combustion engine unit is cooled equally regardless of the temperature load.
The hydraulic cooling system can also be of several varieties:
- Thermosiphon- circulation is carried out due to the difference in density of hot and cold liquids. Thus, the cooled antifreeze displaces hot liquid from the power unit, sending it to the radiator channels.
- Forced- the circulation of the coolant is due to the pump.
- Combined- heat is removed from most of the engine by force, and some sections are cooled by a thermosyphon method.
The forced system is perhaps the most effective and is used in most modern passenger cars.
Essential elements
The engine cooling system contains the following elements:
- Cooling jacket or " water jacket". It is a system of channels passing in the cylinder block.
- Cooling radiator - a device for cooling the liquid itself. Consists of curved tube channels and metal fins for better heat dissipation. Cooling occurs both due to the oncoming air flow and the internal fan.
- Fan. Element of the cooling system, designed to enhance the flow of air. On modern cars, it turns on only when the temperature sensor is triggered, when the radiator is unable to fully cool the liquid with an oncoming air flow. In older models of cars, the fan runs constantly. Rotation is transmitted to it from crankshaft through a belt drive.
- pump or pump. Provides circulation of coolant through the channels of the system. It is driven by a belt or gear drive from the crankshaft. As a rule, powerful engines with direct fuel injection are equipped with an additional pump.
- Thermostat. The most important part of the cooling system that controls the circulation in a large cooling circle. The main task is to ensure normal temperature regime when operating the vehicle. Usually installed at the junction of the inlet pipe and the cooling jacket.
- Expansion tank - a container necessary to collect excess coolant that occurs during its heating.
- Heating radiator or stove. In its design, it is similar to a cooling radiator in a smaller size. However, it is used exclusively for heating the vehicle interior in winter period and direct role in ICE cooling does not play.
Circles of circulation
The cooling system in the car has two circles of circulation: large and small. It is the small one that is considered the main one, since when the unit is started, coolant immediately begins to circulate through it. Only channels are involved in the work of the small circle cylinder block, pump, as well as a radiator for heating the interior. The circulation takes place in a small circle until the internal combustion engine reaches normal operating temperature, after which the thermostat trips and opens a large circle. Thanks to this system, engine warm-up is significantly reduced, and in winter time the system does not so much cool the unit as it maintains its normal temperature regime.
A fan, a cooling radiator, inlet and outlet channels, a thermostat, an expansion tank, as well as those elements that take part in the functioning of a small circle are involved in the work of a large circle. The outer circle, also known as the big circle, starts working when the temperature of the coolant reaches 80-90 ° C, and ensures its cooling.
How the system works
In general, the operation of the system is quite simple. Powered hydraulic pump provides circulation of coolant through the cylinder block jacket. The circulation rate depends on the number of revolutions of the crankshaft of the internal combustion engine.
The antifreeze passing through the channels in the cylinder block removes excess heat from the unit and flows back into the pump receiving compartment, bypassing the thermostat. When the temperature of the coolant reaches 80-90 ° C, the thermostat opens a large circle of circulation, blocking the small one. Thus, the liquid after the cylinder block is sent to the cooling radiator, where its temperature is reduced due to the oncoming air flow and the fan. Further, the process is repeated.
Possible problems and their solution
Despite the simplicity of the design, the cooling system of the power unit is capable of failing during the operation of the vehicle. In this regard, the engine will operate at elevated temperatures, due to which the resource of its parts will be significantly reduced. The reasons for the incorrect operation of the cooling can be completely different.
Thermostat wear
Most often, problems in the system are associated precisely with the valve that switches circulation circles, it is also a thermostat. If the part is stuck in one position or the valve closes the channels of the circulation circles loosely, it may take much longer for the engine to warm up, or vice versa, the unit will begin to overheat without sufficient cooling.
The principle of operation of the thermostat
As a rule, the breakdown of the thermostat is associated with a violation of its integrity. The basis of the valve is thermal wax, which, when heated, expands and compresses the membrane, which opens a large circle of circulation. If the wax leaks out of the part for any reason, the valve will stop functioning and the antifreeze will not be able to fully cool. It can also cause wear untimely replacement coolant or its low quality. Corrosion of the thermostat spring causes the part to stick in the open or less commonly closed position. In both cases, the engine will not be able to run normally. temperature range- the liquid will either be constantly cooled, even when it is not necessary, or vice versa, it will be hot all the time.
Determining wear is quite simple and can be done in two ways. The easiest way to check is to make a non-removable method. To do this, immediately after starting the engine, touch the radiator inlet pipe. If it became warm almost immediately after starting the internal combustion engine, this indicates that the thermostat is stuck in the open position. Conversely, when the nozzle remains cold, even if the temperature reading is at its peak, this indicates the inability of the thermostat to open.
You can more accurately make sure that the reason for the incorrect operation of the cooling system lies precisely in the malfunction of the thermostat by dismantling it. The removed valve is placed in a container with water and heated. When the water temperature reaches 90 ° C, a serviceable valve must definitely work - the thermostat stem will move. If this does not happen, it is safe to assume that the part is defective.
A failed thermostat cannot be repaired, but requires mandatory replacement. Its cost for most cars rarely exceeds 1000 rubles. It is quite possible to replace the valve yourself, without visiting a car service.
Hydraulic pump problems
One of the reasons for the overheating of the power unit of the machine may be a malfunction of the cooling system pump. Most often, the problem is that the hydraulic pump drive belt has broken or its tension is too weak. In this case, the pump will stop pumping antifreeze, or it will not do it fully. Checking this is quite simple, you just need to bring the engine and observe the behavior drive belt. If it works with overshoots, the tension should be increased or the belt should be replaced with a new one. Most often this solves the problem.
There are situations when the problem lies in the pump itself: wear of the impeller, bearing, sometimes even a crack in the shaft is possible. Among other things, the joints between the nozzles and the pump may not be tight, and created by the pump pressure will cause coolant to leak. Diagnosing a leak is quite simple, you need to put sheets of white paper on the floor under the engine for several hours. If even small spots of blue or greenish color are visible on it, this indicates wear on the pump gaskets.
You can check the operation of the pump itself by pinching the upper radiator hose with your fingers for a few seconds while the unit is running. A working pump will create strong pressure and after releasing the hose, it will feel like the liquid quickly ran along the line. It is also worth remembering that increased noise ICE operation and backlash of the pump pulley indicate bearing wear. Usually its wear is associated with the seepage of fluid through the stuffing box, which washes away the grease from the bearing.
The coolant pump, unlike the thermostat, can be partially replaced, but often car owners prefer to fully change the mechanism.
Pump replacement:
- First of all, it is necessary to disconnect the mass of the car from the battery, and the piston of the first cylinder must be in the upper dead center. Remove the belt tension roller and remove the camshaft pulley.
- Next, drain the coolant from the bottom plug in the radiator.
- Unscrewing fixing bolts the pump must be disconnected from the cylinder block.
- Assessing the visually removed mechanism, it is important to determine its wear. If the impeller, oil seal and drive gear are damaged, it is better to replace the pump completely.
- The new mechanism must be installed with new gasket, since the former may even have minor damage which will subsequently lead to coolant leakage. The pump is installed in such a way that the number indicated on the body faces up.
- Further assembly is carried out in reverse orders disassembly. It is better to fill in a new coolant, but you can also use the one that was, if its resource has not yet been exhausted.
Heatsink and fan problems
Insufficient engine cooling may be due to problems with the radiator and fan. First of all, it is worth remembering that a radiator that is too heavily clogged with dust and insects is unable to fully cool both the oncoming air flow and the fan. Often cleaning it solves the problem with cooling.
The device is a "classic" engine cooling radiator. In many modern engines, the coolant is not poured through the radiator neck, but into the expansion tank.
And yet, more serious situations are possible - radiator cracks, which can occur both in an accident and as a result of corrosion. The radiator in most cases can be restored. Brass and copper are repaired by soldering, and aluminum with special sealants.
Before soldering, the damaged areas are carefully cleaned with an emery cloth until a metallic sheen appears. After that, the crack is treated with a soldering flux and a uniform layer of solder is applied using a powerful soldering iron (see video).
It is impossible to solder an aluminum radiator, however, special sealants are offered for their repair, or you can use the usual “cold welding”. Before starting to repair cracks, it is important to clean the defective areas well. The adhesive mass is well kneaded to a homogeneous state and applied to the problem area. It is worth remembering that you can operate the car only the next day after the repair - epoxy glue dries for a long time.
As for the cooling fan, its failure may be due to a broken electrical wiring or a violation of the drive from the crankshaft if the rotation is transmitted from the power unit.
In the first case, it is worth visually assessing the condition of the wires going to the fan motor, if a break is detected, you need to reconnect the damaged contacts. If the condition of the wires is normal, but the fan still does not work, the engine itself or the sensor responsible for its timely switching on may have broken. In this case, it is better to contact a car service, where they will determine the reason why the fan does not turn on. In case of problems with the sensor, the airflow may either continuously or not turn on at all.
In cars where the fan starts to rotate when torque is transmitted from the engine, the breakdown is most often associated with a broken drive belt. Its replacement is quite simple: it is necessary to loosen the pulley tension and install a new belt.
Learn more about the device and repair of the cooling fan.
Flushing the cooling system and replacing the fluid
The hydraulic cooling system requires timely flushing of the lines, otherwise corrosion, salt deposits, and other contaminants may form on the walls of the channels.
Causes of clogging
The main cause of system contamination is the use as a coolant plain water. Running tap water contains a large number of salts, creates scale and rust on the walls of highways. The use of distilled water is less harmful, but it is not able to provide full cooling during the hot period. In addition, in winter, at sub-zero temperatures, the water will freeze and expanding can violate the integrity individual parts and connections.
The use of high-quality antifreeze or antifreeze is more appropriate. Special substances for cooling have a significant resource and do not freeze even at very low temperatures. However, the additives contained in the composition, over time, begin to precipitate, clogging the system.
Washing process
First of all, before flushing, all the coolant is drained through the outlet plug on the radiator, located at the very bottom, and on the cylinder block to remove residues.
It is important to remember that fluid draining should only be carried out on a cold engine!
After draining, the plugs are re-twisted and water is poured into the expansion tank with citric acid or better a special cleaning fluid.
Next, the engine starts and runs in idle mode for 15 minutes. In this case, it should be ensured that a large circle of circulation opens. Also, when washing, do not forget that saloon stove must operate in the maximum heating mode. When the unit has cooled down, the liquid can be drained by opening the radiator and cylinder block plugs. It is recommended to repeat this process until a clean liquid without visible impurities flows out when draining.
Filling with new coolant can be carried out immediately after flushing. Pour antifreeze or antifreeze into the expansion barrel carefully and slowly to avoid the formation air locks in system.
When the tank is almost completely filled, it must be closed and the internal combustion engine run for several minutes so that the liquid spreads evenly throughout the system. Further, after turning off the unit, antifreeze or antifreeze is added to a level between the maximum and minimum marks on the barrel.
In conclusion, it should be said that fundamental difference there is no antifreeze or antifreeze in the use. However, in many countries of the world, automakers have long ceased to use antifreeze, since its effectiveness is somewhat lower. Modern antifreeze is made using the latest technologies and to a greater extent protects the engine from overheating, and the cooling system lines from contamination.
Let's remember a little more about this system cooling.
IN liquid cooling system special coolants are used - antifreeze various brands having a thickening temperature of 40 ° C and below. Antifreezes contain anti-corrosion and anti-foam additives that prevent scale formation. They are highly toxic and require careful handling. Compared to water, antifreezes have a lower heat capacity and therefore remove heat from the engine cylinder walls less intensively.
So, when cooling with antifreeze, the temperature of the cylinder walls is 15 ... 20 ° C higher than when cooling with water. This accelerates engine warm-up and reduces cylinder wear, but in summer time may cause the engine to overheat.
The optimal temperature regime of the engine with a liquid cooling system is considered to be one at which the temperature of the coolant in the engine is 80 ... 100 ° C in all engine operating modes.
Used in car engines closed(sealed) fluid system cooling With forced circulation coolant.
The internal cavity of a closed cooling system does not have a constant connection with the environment, and communication is carried out through special valves (at a certain pressure or vacuum) located in the radiator plugs or expansion tank systems. The coolant in such a system boils at 110 ... 120 ° C. Forced circulation of coolant in the system is provided by a liquid pump.
Engine cooling system consists of from:
- cooling jacket for the head and cylinder block;
- radiator;
- pump;
- thermostat;
- fan;
- expansion tank;
- connecting pipes and drain cocks.
In addition, the cooling system includes a heater for the interior of the car body.
The principle of operation of the cooling system
I suggest you first consider circuit diagram cooling systems.
1 - heater; 2 - engine; 3 - thermostat; 4 - pump; 5 - radiator; 6 - cork; 7 - fan; 8 - expansion tank;
And — a small circle of circulation (the thermostat is closed);
A + B - a large circle of circulation (the thermostat is open)
The circulation of liquid in the cooling system is carried out in two circles:
1. Small circle- the fluid circulates when starting a cold engine, providing it fast warm-up.
2.Big circle- the movement circulates when the engine is warm.
To put it simply, the small circle is the circulation of coolant WITHOUT a radiator, and the large circle is the circulation of coolant THROUGH the radiator.
The device of the cooling system differs in its structure depending on the model of the car, however, the principle of operation is the same.
The principle of operation of this system can be seen in the following videos:
I propose to disassemble the device of the system according to the sequence of work. So, the beginning of the operation of the cooling system occurs when the heart of this system, the liquid pump, is started.
1. Water pump
The liquid pump provides forced circulation of liquid in the engine cooling system. Centrifugal-type vane pumps are used on car engines.
Search our liquid pump or water pump should be on the front of the engine (this front is the one that is closer to the radiator and where the belt / chain is located).
The liquid pump is connected by a belt to the crankshaft and the generator. Therefore, to find our pump, it is enough to find crankshaft and find a generator. We'll talk about the generator later, but for now I'll just show you what to look for. The generator looks like a cylinder attached to the engine case:
1 - generator; 2 - liquid pump; 3 - crankshaft
So, we figured out the location. Now let's look at its device. Recall that the structure of the entire system and its parts is different, but the principle of operation of this system is the same.
1 - Pump cover;2 — A persistent sealing ring of an epiploon.
3 - Oil seal; 4 - Pump roller bearing.
5 - Fan pulley hub;6 - Locking screw.
7 - Pump roller;8 - Pump housing;9 - Pump impeller.
10 - Receiving pipe.
The operation of the pump is as follows: the pump is driven from the crankshaft through a belt. The belt turns the pump pulley by turning the pump pulley hub (5). That, in turn, drives the pump shaft (7), at the end of which there is an impeller (9). The coolant enters the pump housing (8) through the intake pipe (10), and the impeller moves it into the cooling jacket (through a window in the housing, as seen in the figure, the direction of movement from the pump is shown by an arrow).
Thus, the pump is driven by the crankshaft, the liquid enters it through the intake pipe and goes into the cooling jacket.
The operation of the liquid pump can be seen in this video (1:48):
Let's now see where the fluid comes from in the pump? And the liquid enters through a very important detail- thermostat. It is the thermostat that controls the temperature.
2. Thermostat
The thermostat automatically adjusts the water temperature to speed up engine warm-up after starting. It is the operation of the thermostat that determines in which circle (large or small) the coolant will go.
This unit looks like this in reality:
The principle of operation of the thermostat very simple: the thermostat has a sensitive element, inside of which there is a solid filler. At a certain temperature, it begins to melt and opens the main valve, while the additional one, on the contrary, closes.
Thermostat device:
1, 6, 11 - branch pipes; 2, 8 - valves; 3, 7 - springs; 4 - balloon; 5 - diaphragm; 9 - stock; 10 - filler
The operation of the thermostat is simple, you can see it here:
The thermostat has two inlet pipes 1 and 11, an outlet pipe 6, two valves (main 8, additional 2) and a sensitive element. The thermostat is installed in front of the inlet to the coolant pump and is connected to it through pipe 6.
Compound:
Throughbranch pipe 1 connects Withengine cooling jacket,
Through branch pipe 11- with bottom diverting radiator tank.
The sensitive element of the thermostat consists of a cylinder 4, a rubber diaphragm 5 and a rod 9. Inside the cylinder, between its wall and the rubber diaphragm, there is a solid filler 10 (fine-crystalline wax), which has a high volume expansion coefficient.
The main valve 8 of the thermostat with spring 7 starts to open when the coolant temperature exceeds 80 °C. At a temperature of less than 80 ° C, the main valve closes the outlet of the liquid from the radiator, and it flows from the engine to the pump, passing through the open additional valve 2 of the thermostat with spring 3.
When the temperature of the coolant rises above 80 °C, the solid filler melts in the sensitive element, and its volume increases. As a result, the rod 9 comes out of the cylinder 4, and the cylinder moves up. At the same time, additional valve 2 begins to close and at a temperature of more than 94 ° C blocks the passage of the coolant from the engine to the pump. The main valve 8 in this case opens completely, and the coolant circulates through the radiator.
The operation of the valve is clearly and clearly shown in the figure below:
A - a small circle, the main valve is closed, the bypass valve is closed. B - a large circle, the main valve is open, the bypass valve is closed.
1 - Inlet pipe (from the radiator); 2 - Main valve;
3 - Thermostat housing; 4 - Bypass valve.
5 - Branch pipe of the bypass hose.
6 - Pipe for supplying coolant to the pump.
7 - Thermostat cover; 8 - Piston.
So, we figured out the small circle. We disassembled the device of the pump and thermostat connected to each other. And now let's move on to the big circle and the key element of the big circle - the radiator.
3. Radiator(radiator/cooler)
Radiator provides heat dissipation of the coolant in environment. On cars tubular-lamellar radiators are used.
So, there are 2 types of radiators: collapsible and non-collapsible.
Below is their description:
I want to say again about the expansion tank (expansion tanks)
A fan is installed next to the radiator or on it. Let's now move on to the device of this very fan.
4. Fan(fan)
The fan increases the speed and amount of air passing through the radiator. Four- and six-blade fans are installed on car engines.
If a mechanical fan is used,
The fan includes six or four blades (3) riveted to the crosspiece (2). The latter is screwed to the fluid pump pulley (1) which is driven by the crankshaft via a belt drive (5).
As we said earlier, the generator (4) is also engaged.
If an electric fan is used,
then the fan consists of an electric motor 6 and a fan 5. The fan is four-blade, mounted on the motor shaft. The blades on the fan hub are located unevenly and at an angle to the plane of its rotation. This increases the flow of the fan and reduces the noise of its operation. For more effective work the electric fan is located in the casing 7, which is attached to the radiator. The electric fan is attached to the casing on three rubber bushings. The electric fan is switched on and off automatically by sensor 3, depending on the temperature of the coolant.
So let's sum it up. Let's not be unfounded and summarize on some picture. You should not focus on a specific device, but you need to understand the principle of operation, because it is the same in all systems, no matter how different their device is.
When the engine is started, the crankshaft starts to rotate. Through a belt drive (let me remind you that the generator is also located on it), rotation is transmitted to the pulley of the liquid pump (13). It drives the impeller shaft inside the fluid pump housing (16). The coolant enters the engine cooling jacket (7). The coolant then returns to the fluid pump via the outlet (4) through the thermostat (18). At this time, the thermostat is open bypass valve, but the main one is closed. Therefore, the liquid circulates through the engine jacket without the participation of the radiator (9). This ensures that the engine warms up quickly. As the coolant heats up, the main thermostat valve opens and the bypass valve closes. Now fluid cannot flow through the thermostat bypass (3) and is forced to flow through the inlet (5) into the radiator (9). There the liquid is cooled and flows back to the liquid pump (16) through the thermostat (18).
It is worth noting that some of the coolant enters the heater from the engine cooling jacket through pipe 2 and returns from the heater through pipe 1. But we will talk about this in the next chapter.
I hope now the system will become clear to you. After reading this article, I hope it will be possible to navigate in another cooling system, understanding the principle of this one.
I suggest you also take a look at the following article:
Since we have touched on the heating system, my next article will be about this system.
The photo shows a diagram of the engine cooling system Nissan Almera G15
The cooling system of standard type engines cools its heated parts. In systems modern cars It also performs other functions:
- cools the oil of the lubrication system;
- cools the air circulating in the turbocharging system;
- cools the exhaust gases in their recirculation system;
- cools working fluid automatic box gear;
- heats the air circulating in ventilation, heating and air conditioning systems.
More often than others, cars use a liquid cooling system. It evenly and effectively cools engine parts and works with less noise than air. Based on the popularity of the liquid system, it is on its example that the principle of operation of car engine cooling systems as a whole will be considered.
Engine cooling system diagram
The photo shows a diagram of the engine cooling system of a VAZ 2110 car with a carburetor and a VAZ 2111 with an injector (equipment for fuel injection).
For petrol and diesel engines similar designs of cooling systems are used. Their standard set elements are as follows:
- ordinary, oil radiator and coolant radiator;
- radiator fan;
- centrifugal pump;
- thermostat;
- heater heat exchanger;
- expansion tank;
- engine cooling jacket;
- control system.
Let's look at each of these elements individually:
1. Radiators.
- In a conventional radiator, the heated liquid is cooled by a counterflow of air. To increase its efficiency, the design uses special device tubular type.
- The oil cooler is designed to reduce the oil temperature of the lubrication system.
- To cool the exhaust gases, their recirculation systems use a third type of radiator. It allows you to cool fuel-air mixture during its combustion, due to which less nitrogen oxides are formed. The additional radiator is equipped with a separate pump, which is also included in the cooling system.
- hydraulic;
- mechanical (connected on a permanent basis to the crankshaft of the car engine);
- electric (powered by battery current).
3. Centrifugal pump. With the help of a pump in the cooling system, the circulation of its liquid is ensured. The centrifugal pump can be equipped different type drive, for example, belt or gear. For turbocharged engines, in addition to the main one, an additional centrifugal pump can be used for more effective cooling turbocharger and charge air. The engine control unit is used to control the operation of the pumps.
4. Thermostat. The thermostat regulates the amount of fluid entering the radiator. A thermostat is installed in the pipe leading to the radiator from the engine cooling jacket. Thanks to the thermostat, you can control the temperature of the cooling system.
In vehicles with powerful engine can be used in a slightly different way - with electric heating. It is able to regulate the temperature regime of the system fluid in a two-stage range with three operating positions.
In the open state, such a thermostat is during maximum engine operation. At the same time, the temperature of the coolant passing through the radiator drops to 90 ° C, thereby reducing the likelihood of engine knocking. In the remaining two operating positions of the thermostat (open and half-open), the temperature of the liquid will be maintained at around 105 °C.
5. Heat exchanger of the heater. The air entering the heat exchanger is heated for its subsequent use in heating system car. To increase the efficiency of the heat exchanger, it is placed directly at the outlet of the coolant that has passed through the engine and has a high temperature.
6. Expansion tank. Due to changes in the temperature of the coolant, its volume also changes. To compensate for it, an expansion tank is built into the cooling system, which maintains the volume of liquid in the system at the same level.
7. Engine cooling jacket. In design, such a jacket is a fluid channel passing through the engine head and cylinder block.
8. Control system. As control elements of the engine cooling system, it can be represented following devices:
- Temperature sensor of the circulating liquid. The temperature sensor converts the temperature value into the corresponding electrical signal value, which is fed to the control unit. In cases where the cooling system is used for cooling exhaust gases or in other tasks, it can be installed one more temperature sensor installed at the outlet of the radiator.
- Control unit on an electronic basis. Receiving electrical signals from the temperature sensor, the control unit automatically responds and performs appropriate actions on other actuating elements of the system. Usually, the control unit has software, which performs all the functions of automating the signal processing process and setting up the operation of the cooling system.
- Also, the following devices and elements can be involved in the control system: a relay for cooling the motor after it stops, an auxiliary pump relay, a thermostatic heater, a radiator fan control unit.
The principle of operation of the engine cooling system in action
The well-established operation of cooling is due to the presence of a control system. In vehicles with modern engines her actions are based on mathematical model, which takes into account various indicators of system parameters:
- lubricating oil temperature;
- the temperature of the fluid used to cool the engine;
- ambient temperature;
- other important indicators that affect the operation of the system.
By using centrifugal pump forced circulation of coolant in the system. Passing through the cooling jacket, the liquid heats up, and once it enters the radiator, it cools down. By heating the liquid, the engine parts themselves cool down. In the cooling jacket, the liquid can circulate both in the longitudinal (along the line of cylinders) and in the transverse direction (from one collector to another).
The circle of its circulation depends on the temperature of the coolant. During engine start, he and the coolant are cold, and in order to speed up its heating, the liquid is directed to a small circle of circulation, bypassing the radiator. In the future, when the engine is heated, the thermostat heats up and changes its operating position to half-open. As a result, the coolant begins to flow through the radiator.
If the counter air flow of the radiator is not enough to lower the temperature of the liquid to the required value, the fan turns on, generating additional air flow. The cooled liquid enters the cooling jacket again and the cycle repeats.
If the car uses a turbocharger, then it can be equipped with a dual-circuit cooling system. Its first circuit cools the engine itself, and the second - the charge air flow.
See educational video about the principle of operation of the engine cooling system:
COOLING SYSTEM
The cooling system is designed to maintain the normal thermal regime of the engine.
When the engine is running, the temperature in its cylinders rises above 2000 degrees, and the average is 800 - 900 ° C! If you do not remove heat from the “body” of the engine, then after a few tens of seconds after starting, it will no longer be cold, but hopelessly hot. Next time you can run your cold engine just after a major overhaul.
The cooling system is needed to remove heat from the mechanisms and engine parts, but this is only half of its purpose, though more than half. To ensure a normal workflow, 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, a liquid cooling system is used, closed type, with forced fluid circulation and expansion tank (Fig. 25).
Rice. 25 Scheme of the engine cooling system
a) small circle of circulation
a) a large circle of circulation
1 - radiator; 2 - pipe for circulation of 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 cooling system consists of:
- cooling jackets for the block and cylinder head,
- centrifugal pump,
- thermostat,
- radiator with expansion tank
- fan,
- connecting pipes and hoses.
In figure 25, you can easily distinguish two circles of coolant circulation. The small circulation circle (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 system, there is a coolant temperature gauge on the instrument panel. normal temperature coolant during engine operation should be in the range of 80-90 ° C (see Fig. 63).
I risk getting judgmental words addressed to me, but let's imagine that a running engine is still a living organism. The temperature of any living organism is a constant value, and any change in it leads to backfire. The same thing happens with the engine, it will not be able to work normally if its thermal conditions are not up to par.
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 the engine crankshaft pulley. The belt tension is regulated by the deviation of the generator housing (see Fig. 59a) or tension roller drive camshaft engine (see Fig. 11b).
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. 25) to warm it up as soon as possible. When the temperature in the cooling system rises above 80 - 850, the thermostat automatically opens and part of the liquid enters the radiator for cooling. At high temperatures, the thermostat opens completely and already 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 "webs" that form a large cooling surface area.
Well, a household example car radiator- everyone knows. Everyone in the house has radiators (batteries) of central or local heating. They also have a special configuration, and the larger the total area of the complex surface of the radiator, the warmer it is in your house. And at this time, the water in the heating system is actively cooled, that is, it gives off heat.
Expansion tank necessary to compensate for changes in the volume and pressure of the coolant during its heating and cooling.
Fan 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.
There are two types of fans: 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 degrees.
Pipes and hoses are used to connect the engine cooling jacket to the thermostat, pump, radiator and expansion tank.
The interior heater is also included in the engine cooling system. The hot coolant passes through the heater core and heats the air that enters the vehicle interior. The air temperature in the cabin is regulated by a special tap, with which the driver adds or reduces the flow of fluid passing through the heater radiator.
The main malfunctions of the cooling system.
Coolant leakage may appear due to 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 may be due to insufficient level coolant, loose fan belt tension, clogged radiator tubes, or a malfunctioning thermostat.
To eliminate the malfunction, 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 one-time overheating of the engine breaks the structure of the metal,
at the same time, 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. Even if you are a philologist by education and have not hammered a single nail in this life, you can still see something and take timely measures to extend the life of your car.
If the coolant level in the expansion tank has dropped or there is no liquid at all, then first you need to add it, and then figure out (on your own or with the help of a specialist) where it went.
During the operation of the engine, the liquid heats up to a temperature close to the boiling point, which means that the water in its composition 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.
Fluid leakage 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.
It is necessary to control the fluid level in the tank at least once a week, and if there are leaks, then it is necessary to top up, find and eliminate the cause of the level decrease. In other words, you need to put in order the cooling system of your engine. Otherwise, he may become seriously "ill" and require "hospitalization".
Practically in all domestic cars as a coolant, a special low-freezing liquid called TOCOL A-40 is used. The figure (minus 40 ° shows the temperature at which the liquid begins to freeze (crystallize). In the conditions of the Far North, TOSOL A-65 is used, and accordingly it will begin to freeze at a temperature of minus 65 °.
TOSOL A-40 is a mixture of water with ethylene glycol and additives. Such a solution combines a lot of advantages. In addition to the fact that it begins to freeze only after the driver himself has already frozen (just kidding), TOSOL also has anti-corrosion, anti-foaming properties and practically does not form deposits in the form of ordinary scale, since it contains pure distilled water. Therefore, only distilled water can be added to the cooling system.
When operating a car, it is necessary to 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 that you carry a spare belt with you. If not yourself, then one of the "gentlemen" on the road will help you change it.
The coolant may boil and cause engine damage if the fan motor sensor fails. Since the electric fan has not been commanded to turn on, 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, some vibration and a little additional noise are felt. There would be a desire to control, but there will always be ways.
It is especially unpleasant when the engine "boils" while driving off-road at low speed in the hot summer. Therefore there is practical advice for those who like to explore the hinterlands of their native land and also know how to hold a screwdriver in their hands.
If you add another toggle switch in the passenger compartment (or use a free one), with which you can manually turn on the electric fan of the cooling system, then the failed sensor will not interrupt your trip. By controlling the temperature of the coolant on the device, you can decide when to turn on and when to turn off the fan.
If on the way (and more often in a traffic jam) you notice that the coolant temperature is approaching critical, 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 radiator of the interior heater. 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 continue to closely monitor the arrow of the engine temperature gauge. If it enters the red zone, stop immediately, open the hood and "cool down".
Over time, the thermostat can cause trouble if it stops letting fluid through a large circle of circulation. It's easy to tell if a thermostat is working. The radiator should not heat up (determined by hand) until the pointer of the coolant temperature gauge has reached 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. But 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. This means that the cylinder head gasket is damaged and coolant enters the oil pan engine crankcase. If you continue to operate the engine with oil, half consisting of TOSOL, then the wear of engine parts becomes catastrophic. And this, in turn, is already associated with a very expensive repair.
The 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”, he will replace the bearing in a timely manner. Otherwise, it will still have to be changed, but already after being late for the airport or for a business meeting, due to a “suddenly” broken car.
Each of the drivers must know and remember that on a hot engine, the cooling system is in a state of high blood pressure! If the engine of your car overheated and “boiled”, then, of course, you need to stop and open the hood of the car, but I do not advise you to open the radiator cap. To speed up the process of cooling the engine, this will practically do nothing, but you can get severe burns.
Everyone knows what turns out to be for smartly dressed guests, clumsily opened a bottle of Champagne. 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.
From this we can conclude that the driver of that foreign car not only had a short driving experience, but he also had not read this book! However, this is his misfortune, this should not happen to our reader!
