Purpose of the device and operation of the cooling system. Forced air cooling

COOLING SYSTEM

The cooling system is designed to maintain normal engine thermal conditions.

When the engine is running, the temperature in its cylinders rises above 2000 degrees, and the average is 800 - 900 o C! If you do not remove heat from the “body” of the engine, then within a few tens of seconds after starting, it will no longer become cold, but hopelessly hot. The next time you can start your cold engine only after it has been overhauled.

The cooling system is needed to remove heat from the mechanisms and parts of the engine, but this is only half of its purpose, although it is the larger half. To ensure a normal working process, it is also important to speed up the warm-up of a cold engine. And this is the second part of the cooling system.

Typically used fluid system cooling, closed type, With forced circulation fluid and expansion tank (Fig. 25).

Rice. 25 Engine cooling system diagram
a) small circle of circulation
a) large circle of circulation

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

The cooling system consists of:

• cooling jackets of 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 quickly as possible. And when the blue arrows join the red arrows, the already heated liquid begins to circulate in a large circle, cooling in the radiator. Leads this process automatic device - thermostat.

To monitor the operation of the system, there is a coolant temperature indicator on the instrument panel. Normal temperature When the engine is running, the coolant should be within 80-90 o C (see Fig. 63).

I risk receiving condemning 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 unpleasant consequences. The same thing happens with the engine; it will not be able to work normally if its thermal conditions do not correspond to the norm.

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

Centrifugal pump causes fluid 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 adjusted by deflecting the generator housing (see Fig. 59a) or tension roller drive camshaft engine (see Fig. 11b).

Thermostat designed to maintain constant optimal thermal conditions 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 quickly as possible. When the temperature in the cooling system rises above 80 - 85O, the thermostat automatically opens and part of the liquid enters the radiator for cooling. At high temperatures, the thermostat opens completely and all the hot liquid is directed in a large circle for its active cooling.

Radiator serves to cool the liquid passing through it due to the air flow that is created when the car moves or using a fan. The radiator has many tubes and "membranes" that create a large cooling surface area.

Well, everyone knows the everyday example of a car radiator. Everyone in the house has radiators (batteries) for 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 heating and cooling.

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

Two types of fans are used: always on, belt driven by 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 engine cooling system also includes a cabin heater. Hot coolant passes through the heater core and heats the air supplied to the vehicle interior. The air temperature in the cabin is regulated by a special tap, with which the driver increases or decreases the flow of liquid passing through the heater radiator.

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 clamps securing the hoses and tubes, and replace the damaged parts with new ones. If the radiator tubes are damaged, you can try to “patch” holes and cracks, but, as a rule, everything ends with replacing the radiator.

Engine overheating may occur due to insufficient level coolant, low fan belt tension, clogged radiator tubes, as well as a thermostat malfunction.

To eliminate the malfunction, you should restore the fluid level in the cooling system, adjust the fan belt tension, flush the radiator, and replace the thermostat.

Engine overheating often occurs even when the elements of the cooling system are in working order, when the car is moving with low speed And heavy loads to the engine. This happens when driving in heavy road conditions, such as country roads and everyone is tired of city traffic jams. In these cases, it’s worth thinking about your car’s engine, and about yourself too, by taking periodic, at least short-term, “breaks.”

Be careful while driving and do not allow emergency mode engine running!

Remember that even one-time overheating of the engine disrupts 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 your vehicle, you should periodically look under the hood. Even if you are a philologist by training and have not hammered a single nail in this life, you will still be able to see something and take timely measures to extend the life of your car.

If the level of coolant 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 engine operation, the liquid heats up to a temperature close to the boiling point, which means that the water included in its composition will gradually evaporate. If in six months daily use car, the level in the tank has dropped a little, this is normal. But if yesterday the tank was full, and today there is only the bottom in it, then you need to look for a coolant leak.

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

It is necessary to monitor 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 reason for the decrease in level. In other words, you need to put your engine cooling system in order. Otherwise, he may become seriously “ill” and require “hospitalization.”

In almost all domestic cars A special low-freezing liquid called TOCOL A-40 is used as a coolant. The number (minus 40 o) shows the temperature at which the liquid begins to freeze (crystallize). In the far north, TOSOL A-65 is used, and accordingly it will begin to freeze at a temperature of minus 65 o.

TOSOL A-40 is a mixture of water with ethylene glycol and additives. This 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 produce 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 monitor 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 you yourself, then one of the “gentlemen” on the road will help you change it.

The coolant can boil and cause engine damage if the fan motor sensor fails. Since the electric fan has not received a command to turn on, the liquid continues to heat up, approaching the boiling point, without any cooling assistance. But the driver has before his eyes a device with an arrow and a red sector! 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 love to explore the outback of their native land and also know how to hold a screwdriver in their hands.

If you add another toggle switch in the car interior (or use a free one), with which you can manually turn on the electric fan of the cooling system, then a failed sensor will not interrupt your trip. By monitoring the coolant temperature on the device, you can decide when to turn the fan on and off.

If on the road (or 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 interior heater radiator. Fully open the heater tap, turn on the heater fan at full speed, lower the door windows and “sweat” home or to the nearest car service center. But continue to closely monitor the engine temperature gauge needle. If it enters the red zone, stop immediately, open the hood and “cool down.”

Over time, the thermostat can cause trouble if it stops releasing liquid through a large circulation circle. It is not difficult to determine whether the thermostat is working. The radiator should not heat up (determined by hand) until the coolant temperature gauge needle reaches the middle position (thermostat closed). Later, hot liquid will begin to flow into the radiator, quickly heating it, which indicates the timely opening of the thermostat valve. But if the radiator continues to remain cold, then there are two ways. Tap on the thermostat housing, maybe it will open after all, or immediately, mentally and financially, prepare to replace it.

Surrender to a 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 is leaking into the oil pan engine crankcase. If you continue to operate the engine with oil half consisting of antifreeze, the wear of engine parts will become catastrophic. And this, in turn, is already associated with very expensive repairs.

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 after being late for the airport or for a business meeting, due to a “suddenly” broken down car.

Each driver must know and remember that on a hot engine the cooling system is in a state high blood pressure! If your car’s engine overheats and “boils,” then, of course, you need to stop and open the hood of the car, but I do not recommend opening the radiator cap. This will do practically nothing to speed up the engine cooling process, but you can get severe burns.

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

From this we can conclude that the driver of that foreign car not only had little driving experience, but he also had not read this book! However, this is his problem; this should not happen to our reader!

Most of serious malfunctions car is associated with engine overheating. The temperature of the gases in the cylinder reaches 2000 degrees. When fuel burns in the cylinder, a large amount of heat is generated, which must be removed and thereby prevent overheating of engine parts.

Principles of designing cooling systems

A decrease in the efficiency of the cooling system leads to an increase in the temperature of the pistons and a decrease in the gaps between the piston and the cylinder. Thermal gaps are reduced to zero. The piston touches the cylinder walls, scoring occurs, 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 cylinder head, mounting bolts, engine block, etc. Subsequent destruction of the engine is inevitable: cracks in the cylinder head, deformation of the joint planes of the head and the cylinder block itself, cracks in the valve seats, etc. — it’s unpleasant to even list all this, so it’s better not to let it come to that!

The engine and oil cooling system is designed to prevent such developments, 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 English word"antifreeze". Previously, coolants were prepared based on aqueous solutions of monohydric alcohols, glycols, glycerin 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 operating temperature range of the engine and its components, to have high heat capacity and thermal conductivity, not to foam, not to harmful effects on pipes and seals, have lubricating and anti-corrosion properties.

In the 70s, antifreeze was produced based on aqueous solution monoethylene glycol with a crystallization temperature of 40 degrees. It did not require dilution with water when added to the cooling system. This drug was named Antifreeze- by the name of the laboratory “Technology of Organic Synthesis”. Because the name is not patented, then TOSOL is a ready-to-use product, and “antifreeze” is a concentrated solution (although TOSOL is also antifreeze).

Ready-made antifreezes are colored for safety and catchy colors are chosen: blue, green, red. During operation, antifreeze loses beneficial features- anti-corrosion properties decrease, the tendency to foam increases. The service life of domestic coolants is from 2 to 5 years, imported 5-7 years.

The figure below shows a diagram of the 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 cap, 7 - upper pipe, 8 - lower pipe, 9 - radiator fan, 10 - fan switch sensor, 11 - sensor temperature, 12 - pump.

When the engine starts, the water pump begins to rotate. The pump drive may have its own pulley, driven by a belt. auxiliary equipment or driven by rotation of the timing belt. The cooling system contains an impeller, which rotates and drives the coolant. To quickly warm up the engine, the system is “shorted”, i.e. The thermostat is closed and does not allow fluid to enter the radiator. As the temperature of the coolant rises, the thermostat opens, transferring the system to another state when the coolant passes along a long path - through the radiator of the cooling system (the short path is blocked by the thermostat). Thermostats have various characteristics discoveries. Typically the opening temperature is marked on the edge. It’s probably not worth explaining the design of the radiator. A fan switch sensor is installed at the bottom of the radiator. If the coolant temperature reaches a certain value, the sensor will close, and because If it is electrically connected to the break in the power supply circuit of the electric fan, then when it is shorted, the cooling system fan should turn on. As the coolant cools, the fan turns off and the thermostat closes the long path to a short one. It's simple, but not very...

This scheme is the basis, but life does not stand still and various manufacturers 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 engine ECU depending on the readings of the coolant temperature sensor. It is worth paying attention to the situation in which when the ignition is jammed, 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 vehicles, special electric valves are installed on the way to the heater, allowing or blocking the path of coolant (BMW, MERCEDES). Such valves sometimes “help” the cooling system fail.

Troubleshooting the cooling system

Specialists from the AB-Engineering company under the leadership of A.E. Khrulev. has developed a table of the 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. Engine operation at a constantly low temperature is also considered a malfunction, because in this case, the engine operates at an unusual temperature regime. Failure of a 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 engine’s thermal operating conditions in time and does not allow irreversible processes to occur, then repairing the cooling system will not be expensive and time-consuming. Therefore, we strongly recommend that you (and your customers) pay attention to the temperature conditions of the engine.

A. The first thing you need to do is check the connection diagram of the cooling system pipes if the car is not new or has been repaired after being repaired at another service center.

To some, such a proposal may seem funny, but life has shown the opposite, examples:

• the car assembled after a major overhaul had a connection between the crankcase ventilation system pipe and the expansion tank of the cooling system;
• installed non-standard fan with blades directing the air flow in the wrong direction;
• the electric fan blades rotate freely on the shaft of the switched off engine;
• The electric fan connectors are loose or torn, etc.

Inspect the radiator for external clogging. Inspect the areas and paths of natural cooling of the engine. A negative example would be a heavy engine underbody guard that blocks the airflow that cools the engine from below. Sometimes a breakdown of the bumper, the lower part of which has air flow guides to the engine, leads to overheating (VW Passat B3).

B. After the inspection, it is necessary to check the coolant level in the system, the presence and serviceability of the radiator cap valves and expansion tank, and the integrity of the pipes and hoses. Check what kind of 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) reveal any malfunctions, they must be eliminated or taken into account when making a “sentence”. When adding coolant, you need to remember that not all cars are designed with a “just add water” mentality. For example, on a BMW car (M20, E34), when adding coolant, you need to turn on the ignition and set the heater temperature controls to the “maximum heat” mode so that the heater valves turn on and open for the movement of coolant through the system, in addition, you need 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 cabin stove and it often becomes airy.

If there is a suspicion that the engine is airy (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 the 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 the system has an expansion tank, then check the fluid circulation, i.e. its movement through the system. When adding engine speed to 2,500 - 3,000, a powerful jet of coolant should flow into the tank. Air may escape from the plugs that are unscrewed (not completely!) for some time, and as soon as liquid flows out, the plugs must be tightened. As the engine warms up, warm air should come out of the cabin heater. If the engine warms up and the air from the heater is cold, then this is the first sign of airing in the cooling system. It is necessary to turn off the engine and take measures to find and eliminate this malfunction.

If the thermostat is working properly (the opening temperature can vary from 80 to 95 degrees), after warming up, the lower radiator hose should have approximately the same temperature as the upper one. If this is not the case, it means poor coolant flow through the radiator.

If the thermostat is working properly, the cooling system fan should turn on some time after it opens. If the system does not have an electric fan, then it is necessary to check the circuit switch sensor electromagnetic coupling or the operation of the viscous coupling. If the viscous coupling malfunctions, the cooling system fan on a warm engine can be stopped and held by hand (when stopping, be careful - 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 must be directed towards the engine.

The pressure in the cooling system should increase slowly as the engine warms up and drop slowly after the engine is turned off. If the upper pipe leading to the radiator swells when the engine speed increases, it is necessary to check whether some of the exhaust gases are entering the cooling system. This is usually noticeable by an oil film in the expansion tank or bubbling of the coolant. In this case, it usually comes out intensely from the muffler. White smoke from heated and evaporating coolant entering the engine cylinders. In this case, it is necessary to check the engine oil filler neck and sit on it white emulsion, then the coolant is not only in the engine cylinders, but also in the lubrication system (it is necessary to stop movement). Let's give a few examples from the practice of various services that “say” that engine diagnostics are inseparable from the diagnostics of all vehicle systems, including the cooling system.

A MAZDA 626 - the owner complains about uneven engine speed or increased speed idle move. Checking the control system (and self-diagnosis) did not reveal a malfunction. We noticed increased voltage on the coolant temperature sensor.

The control system adds the amount of fuel because reacts to high voltage on the sensor (engine cold). It turned out that there was not enough liquid in the cooling system, the sensor was “bare”. Just added before normal level coolant and speed returns to normal.

FORD vehicles - coolant entered the oil in an unconventional way - through the oil cooling system located around the oil filter.

FORD vehicle - after the engine warmed up, 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, the engine simply cooled down during the work) - the cylinder began to work and the client left. The next day he is with us again. It turned out to be a crack in the cylinder head near the exhaust valve. idle cylinder. As long as the engine is cold, everything is fine. When warmed up, the crack grew larger and began to leak coolant into the cylinder. The mixture became lean and interruptions began, and then the cylinder turned off completely.

There are many such examples that can be given; they are in the practice of every car repairman. The main conclusion everyone who is seriously involved in auto repair should make is to notice and analyze everything significant and insignificant, because these positions can suddenly change places.

The figure shows the liquid cooling system of a carburetor V-engine. Each row of the block has a separate water jacket. The pumped water by the water pump 5 is divided into two streams - into the distribution channels and then into the water jacket of its row of the block, and from them into the jackets of the cylinder heads.

Rice. Engine cooling system ZMZ-53: a - device; b - core; c - blinds; 1 - radiator; 2 - liquid overheat indicator sensor; 3 - radiator cap; 4 - casing; 5 - water pump; 6 - bypass hose; 7 and 12 - outlet and inlet hoses, respectively; 8 - thermostat; 9 - liquid temperature sensor; 10 - drain valve fitting; 11 - cooling jacket; 13 - fan belt; 14 - drain tap; 15 - fan; 16 - blinds; 17 - heater fan; 18 - cabin heater; 19 - blinds plate; 20 - cable

When the cooling system is operating, a significant amount of liquid is supplied to the hottest places - the pipes exhaust valves and spark plug sockets. For carburetor engines, water from the cylinder head jackets first passes through the water jacket of the intake pipe, washes the walls and heats the mixture coming from the carburetor through the internal channels of the pipe. This improves the evaporation of gasoline.

The radiator is used to cool the water coming from the engine water jacket. The radiator consists of upper and lower tanks, a core and mounting parts. The tanks and core are made of brass for better heat conduction.

The core contains a series of thin plates, through which many vertical tubes pass, soldered to them. The water entering through the radiator core branches into a large number of small streams. With this core structure, the water cools more intensely due to an increase in the area of ​​contact of the water with the walls of the tubes.

The upper and lower tanks are connected to the engine cooling jacket by hoses 7 and 12. The lower tank has a tap 14 for draining water from the radiator. To drain it from the water jacket, there are also taps at the bottom of the cylinder block (on both sides).

Water is poured into the cooling system through the neck of the upper tank, closed with plug 3.

To cabin heater 18 hot water comes from the water jacket of the block head and is discharged through a pipe to the water pump. The amount of water supplied to the heater (or the temperature in the driver's cabin) is regulated by a tap.

In system liquid cooling Dual regulation of the thermal regime of the engine is provided - using blinds 16 and a thermostat 8. The blinds consist of a set of plates 19, which are hinged in the bar. In turn, the bar is connected by a rod and a system of levers to the blinds control handle. The handle is located in the cockpit. The doors can be positioned vertically or horizontally.

The water pump and fan are combined in one housing, which is attached through a sealing gasket to a pad on the front wall of the crankcase. A roller 4 is installed in the pump housing 7 on ball bearings. A pulley 2 is attached to its front end using a hub. A cross is screwed to its end, to which the fan impeller 1 is riveted. When the engine is running, the pulley receives rotation from the crankshaft through the belt. The impeller blades 1, located at an angle to the plane of rotation, take air from the radiator, creating a vacuum inside the fan casing. Thereby cold air passes through the core of the radiator, robbing it of heat.

At the rear end of the roller 4, the impeller 5 of the centrifugal water pump is rigidly mounted, which is a disk with curved blades evenly spaced on it. When the impeller rotates, liquid from the supply pipe 8 flows to its center, is captured by the blades and, under the action centrifugal force is thrown to the walls of housing 7 and fed through the tide into the water jacket of the engine.

Rice. Water pump and fan of the ZIL-508 engine: 1 - fan impeller; 2 - pulley; 3 - bearing; 4 - roller; 5 - pump impeller; 6 - gasket; 7 - pump housing; 8 - supply pipe; 9 - bearing housing; 10 - cuff; 11 - sealing washer; 12 - gland seal cage

At the rear end of the roller 4 there is also an oil seal that does not allow water to pass through from the engine water jacket. The seal is mounted in the cylindrical hub of the impeller and locked in it with a spring ring. It consists of a textolite sealing washer 11, a rubber cuff 10 and a spring that presses the washer to the end of the bearing housing. With its protrusions, the washer fits into the grooves of the impeller 5 and is secured with a clip 12.

On a KamAZ vehicle engine, the fan is located separately from the water pump and is driven through a hydraulic coupling. The fluid coupling (Fig. a) includes a sealed casing B filled with liquid. The casing contains two (with transverse blades) spherical vessels D and G, rigidly connected to the drive A and driven B shafts, respectively.

The operating principle of a fluid coupling is based on the action of the centrifugal force of a fluid. If you quickly rotate a spherical vessel D (pump) filled with working fluid, then under the influence of centrifugal force the liquid slides along the curved surface of this vessel and enters the second vessel G (turbine), causing it to rotate. Having lost energy upon impact, the liquid again enters the first vessel, accelerates in it, and the process repeats. Thus, rotation is transmitted from the drive shaft A, connected to one vessel D, to the driven shaft B, rigidly connected to another vessel G. This principle of hydrodynamic transmission is used in technology when designing various mechanisms.

Rice. Fluid coupling: a - principle of operation; b - device; 1 — cylinder block cover; 2 - body; 3 - casing; 4 - drive roller: 5 - pulley; 6 - fan stage; A - drive shaft; B - driven shaft; B - casing; G, D - vessels; T - turbine wheel; H - pump wheel

The fluid coupling is located in the cavity formed by the front cover 1 of the cylinder block and the housing 2, connected by screws. The fluid coupling consists of casing 3, pump H and turbine wheels, drive A and driven B shafts. The casing is connected through drive shaft A to crankshaft using drive roller 4. On the other side, casing 3 is connected to the pump wheel and pulley 5 for driving the generator and water pump. Driven shaft B rests on two ball bearings and is connected at one end to turbine wheel, and the other - with fan hub 6.

The engine fan is located coaxially with the crankshaft, the front end of which is connected by a splined shaft to the drive roller 4 of the fluid coupling drive. By turning the hydraulic coupling switch lever, you can set one of the required fan operating modes: “P” - the fan is constantly on, “A” - the fan turns on automatically, “O” - the fan is turned off (the working fluid is released from the casing). In mode “P” only short-term operation is allowed.

The fan automatically turns on when the temperature of the coolant flowing around the thermal power sensor rises. At a coolant temperature of 85 °C, the sensor valve opens oil channel in the switch housing and working fluid - engine oil- enters the working cavity of the fluid coupling from the main line lubrication system engine.

The thermostat serves to speed up the warm-up of a cold engine and automatically regulate its thermal regime within specified limits. It is a valve that regulates the amount of fluid circulating through the radiator.

On the engines under study, single-valve thermostats with a solid filler - ceresin (petroleum wax) - are used. The thermostat consists of a housing 2, inside of which a copper cylinder 9 is placed, filled with an active mass 8 consisting of copper powder mixed with ceresin. The mass in the cylinder is tightly closed with a rubber membrane 7, on which a guide sleeve 6 with a hole for a rubber buffer 12 is installed. A rod 5 is installed on the latter, connected by a lever 4 to the valve. In the initial position (on a cold engine), the valve is tightly pressed to the seat (Fig. b) of housing 2 by spiral spring 1. The thermostat is installed between pipes 10 and 11, which discharge the heated liquid to the upper radiator tank and the water pump.

Rice. Thermostat with rotary (a-c) and simple (d) valves: a - device of a thermostat with a rotary valve ( carburetor engine ZIL-508); b - the valve is closed; c - the valve is open; d - thermostat device with a simple valve (carburetor engine 3M3-53); 1 - spiral spring; 2 - body; 3 - valve (damper); 4 - lever; 5 - rod; 6 - guide sleeve; 7 - membrane; 8 - active mass; 9 - balloon; 10 and 11 - fluid drain pipes to the radiator and water pump; 12 - rubber buffer; 13 - valve; 14 - spring; 15 - body saddle; A - valve stroke

At a coolant temperature above 75 °C, the active mass melts and expands, acting through the membrane, buffer and rod 5 on lever 4, which, overcoming the force of spring 1, begins to open valve 3 (Fig. c). The valve will open completely at a coolant temperature of 90 °C. In the temperature range of 75...90 °C, the thermostat valve, changing its position, regulates the amount of coolant passing through the radiator, and thereby maintains normal engine temperature conditions.

Figure d shows a thermostat with a simple valve 13 in a position where it is fully open to allow fluid to pass into the radiator, i.e. when its stroke is equal to distance A. At a temperature of 90 °C, when the active mass of the cylinder is melted, the valve together with the cylinder sits down, overcoming the resistance of spring 14. As it cools, the mass in the cylinder is compressed and the spring lifts the valve up. At a temperature of 75 °C, valve 13 is pressed against the seat 15 of the housing, closing the outlet of the liquid into the radiator.

Rice. Steam-air valve: a - steam valve is open; b - air valve is open; 1 and 6 - steam and air valves, respectively; 2 and 5 - springs of steam and air valves; 3 - steam pipe; 4 - plug (cover) of the radiator filler neck

A steam-air valve is necessary to communicate the internal cavity of the radiator with the atmosphere. It is mounted in plug 4 of the radiator filler neck. The valve consists of a steam valve 1 and a air valve 6. The steam valve, under the action of spring 2, tightly closes the radiator neck. If the water temperature in the radiator rises to the limit value (for of this engine), then under steam pressure the steam valve opens and its excess comes out.

When, during cooling of water and condensation of steam, a vacuum is created in the radiator, the air valve opens and flows into the radiator. atmospheric air. The air valve closes under the action of spring 5 when the air pressure inside the radiator is balanced with atmospheric pressure. The air valve drains water from the cooling system when the filler cap is closed. In this case, the radiator tubes are protected from destruction under the influence of atmospheric pressure during engine cooling.

To control the coolant temperature, use warning light and a remote thermometer. The lamp and thermometer pointer are placed on the instrument panel, and their sensors can be in the cylinder head, in the drain pipe, in the intake pipe or in the upper radiator tank.

» Car engine cooling system, principle of operation, malfunctions

The automotive engine cooling system needs to be checked periodically. Many significant car malfunctions are caused by engine overheating. Combustion temperature value air-fuel mixture reaches several thousand degrees. Accordingly, a large amount of heat is generated, which must be removed so as not to overheat the motor, which can lead to serious problems.

Engine overheating problems

Ineffective operation of the cooling system can lead to exceeding the operating temperature of the pistons, reducing thermal gap between the piston and the cylinder walls down to zero. This causes the piston body to touch the cylinder walls, causing scratches and scoring. Also, when overheated, engine oil loses its lubricating properties and the oil film is damaged. The engine may seize due to this.

Overheating of the cooling system and engine is accompanied by different various materials expansion of the cylinder head, block and mounting bolts, which leads to curvature of the mounting surface of the head, pulling out of the bolts, and cracking of the valve seats. It is clear that after such changes it is difficult and sometimes impossible to repair the engine.

Engine coolants

A properly functioning cooling system should prevent overheating, but for the system to function properly, it requires the use of high-quality coolant. Antifreeze at low temperatures technical fluids are called antifreeze (from the English antifreeze). Today, antifreezes are produced, as a rule, based on monoethylene glycol, which is a thick liquid with a boiling point of about 200 °C.

The purpose of the coolant is not only to cool the engine, but also to transfer heat to heat the cabin and heat the fuel in winter. The vehicle coolant must meet the following requirements:

• do not freeze throughout the entire range of engine operating temperatures;
• have high values heat capacity and thermal conductivity;
• do not form foam;
• do not corrode the plastic and rubber of the pipes;
• do not damage the seals;
• lubricate and protect cooling system and engine parts from corrosion;
• do not deposit scale and other deposits of various kinds on the internal walls work surface cooling systems

It is customary to distinguish between the concepts of “antifreeze” and “antifreeze”. It is believed that antifreeze is a finished product, and antifreeze is a concentrate. Although, of course, the composition is the same, just with a different name.

Automotive antifreezes are painted in noticeable, bright colors:

• green,
• orange, or shades of red
• cyan (blue),
• turquoise

This is done for the sake of safety, because antifreeze is very poisonous. As the liquid is used, it loses the necessary properties - the lubricating and anti-corrosion parameters are gradually lost, and the tendency to form foam increases.

Important: The service life of antifreeze is between 2–7 years.

After starting the car, together with the engine, the cooling system pump (also called a pump, water pump) begins to rotate, unless of course electronic connection pumps. The pump is driven into rotation by the timing belt or by means of a belt attachments- it depends on the design of the engine specific model. The water pump impeller rotates to pump coolant through the system. To quickly reach operating temperature, a small circuit is provided in the car’s cooling system, that is, liquid circulates only inside the engine, the thermostat is closed, and antifreeze is not supplied to the radiator.

As soon as the engine warms up to a certain temperature, the thermostat opens, passing antifreeze or antifreeze through the large cooling system circuit. The fluid passes through the radiator where it cools. The radiator is cooled by outside air, freely passing through the radiator grille, or forcedly blown by a fan. After cooling in the radiator, the antifreeze is supplied to the engine cooling system, picks up some of its heat and is again sent in a large circle.

The radiator is equipped with a fan switch sensor, which, when a certain temperature is reached, turns on forced airflow or changes the fan speed. When the rotation speed changes, the amount of air passing through the radiator cells changes, and the cooling efficiency of the liquid is adjusted accordingly. As the liquid in the radiator cools, the fan turns off. If the antifreeze becomes colder than the response value, the large circuit is closed and circulation occurs again in a small circle.

Some cooling systems use several temperature sensors, the location of the sensors is:

• on the radiator of the cooling system,
• on the cylinder head,
• directly on the thermostat housing.

This operating scheme is basic, but manufacturers are constantly improving cooling systems. Some cars do not have sensors for turning on the fan, which is triggered by a signal from the engine control unit depending on the readings of the temperature sensor. Thermostats can also be controlled by the “brains” of the motor, opening and switching circuits not automatically, but by a control signal. In some models, the pipes leading to the heater are equipped with solenoid valves regulating the supply of coolant to the heater radiator. If malfunctioning, these valves can cause cooling system problems.

One of the improvements to the cooling system is an electronically controlled pump, or rather a pump drive, which, depending on the engine temperature, turns on or off the pump, thereby facilitating more efficient thermal regulation and quick warm-up car cooling systems.

Diagnosis of cooling system faults

Engine overheating- this is an operating mode that is caused by boiling of the coolant. However, overheating is not the only problem. Operating the motor at a constantly low temperature is also harmful, since working temperature must be maintained at a certain level. Cold engine consumes more fuel, does not operate with better efficiency, and is subject to increased loads due to the increased viscosity of the lubrication system.

Failure of the thermostat, fan, thermal relay and sensors interferes with the proper functioning of the cooling system. If signs of temperature violations are detected in time and fatal malfunctions do not occur, then repairs most likely will not be too long and expensive. Therefore, it is recommended that all specialists monitor temperature conditions motor operation.

Diagnosis of problems and malfunctions should begin with a cold engine. First you need to check the correct articulation of the pipes and pipes, the assembly of other elements of the cooling system, especially if the car was repaired shortly before the problem occurred. This may sound funny, but there are many examples where cooling does not work correctly due to assembly errors.

Some of these cases:

• after reassembling the engine, the crankcase ventilation hose is connected to the coolant expansion tank;
• a “non-original” cooling fan is installed, due to the incorrect position of the blades of which the air is directed in the wrong direction;
• the fan impeller blades rotate freely on the shaft;
• Sensor or fan connectors are oxidized, loose or damaged.

It would also be useful to carry out visual inspection radiator, perhaps it is dirty, the honeycombs are clogged. Sometimes too tight engine protection can have a negative effect, blocking the path of air from below. A minor accident that only leads to a breakdown of the bumper can lead to overheating - special guides are formed in the bumper through which air passes to the engine ( VW Passat B5).

After visual inspection cooling system, you need to check the level of antifreeze, the serviceability of the valves of the radiator cap or tank, the tightness of hoses and pipes. It makes sense to decide what is poured into the system - antifreeze or just water.

If the first steps helped to identify any malfunctions in the engine cooling system, they must be eliminated or taken into account when making a “diagnosis”. When adding fluid, you must not forget that not every car can simply add antifreeze and that’s it. For example, in some BMWs, when adding coolant, you should turn on the ignition and set the heater adjustment to maximum in order for the heater solenoid valves to open.

If you suspect air has entered the cooling system, you need to unscrew special plugs designed to release air. They are located, as a rule, at the highest point of the system. If your car has an expansion tank, you can check if the fluid is circulating. If, during systematic warming up of the engine, cold air enters the passenger compartment from the heater air ducts, this is the first sign of an air “bubble” in the system.

If the thermostat is known to be working, after warming up the radiator, its lower and upper hoses should have approximately the same temperature. A big difference the temperature of these pipes indicates poor circulation of antifreeze through the radiator.

After a certain period of time after opening the thermostat, as the response temperature is reached, the radiator cooling fan should turn on. If the system does not contain an electric fan, the electromagnetic clutch closure sensor or the functioning of the viscous clutch should be checked. A sign of a malfunction of the viscous coupling can be considered the ability to stop and hold the fan by hand. Be sure to be careful! Try to stop it with a soft object to avoid the possibility of hand injury or damage to the impeller. Air flow in the correct case should be aimed at the engine.

Cooling system pressure the vehicle temperature increases in proportion to the engine warming up and gradually decreases as it cools down. If the upper pipe leading to the radiator swells as the engine speed increases, then it makes sense to make sure that some of the gases from the engine do not enter the system. This happens if cylinder head gasket has broken between the cooling channel and the cylinder or if the cylinder head itself is damaged. One of the signs of this problem is an oil film in the expansion tank. Gases are also indicated by bubbles appearing in antifreeze while the engine is running.

There are many examples of how a malfunctioning cooling system led to serious problems for the owner, including engine replacement. The main conclusion should be made one thing - there are no trifles or unimportant faults in the operation of the car. You need to notice all the changes, analyze them, make correct conclusions. If the car owner does not understand this, the car should be regularly serviced by good specialists.

Replacing coolant, antifreeze or antifreeze
Antifreeze leaves the expansion tank - causes and ways to eliminate them What to do if the heater in your car does not work? The engine gets hot, causes of engine overheating Engine overheating - causes and consequences
Fuel injection system - diagrams and principle of operation

During work they are exposed to very high temperatures, and without removing excess heat its operation is impossible. Main purpose engine cooling systems is cooling the parts of a running engine. The next most important function of the cooling system is heating the air in the cabin. In turbocharged engines, the cooling system reduces the temperature of the air pumped into the cylinders; in cars with turbochargers, it cools the working fluid in . In some car models for additional cooling An oil cooler is installed in the oil.

Cooling systems are divided into two main types:

1. liquid;
2. air

Each of these systems has its own advantages and disadvantages.

Air cooling system It has the following advantages: simplicity of design and maintenance, lighter engine weight, reduced requirements for environmental temperature fluctuations. Disadvantages of engines with air cooled are big loss power on the cooling fan drive, noisy operation, excessive thermal load on individual components, lack of constructive possibility of organizing the cylinders according to the block principle, difficulties with the subsequent use of the rejected heat, in particular for heating the interior.

IN modern engines In cars, an air cooling system is quite rare, and the most common type is a closed-type liquid cooling system.

Design and diagram of a liquid (water) engine cooling system

Liquid cooling system allows you to evenly remove heat from all engine components, regardless of thermal loads. A water-cooled engine is less noisy than an air-cooled engine, less prone to detonation, and warms up faster when starting.

The main elements of the liquid cooling system of both gasoline and diesel engines are:

1. “water jacket” of the engine;
2. cooling system radiator;
3. fan;
4. centrifugal pump (pump);
5. thermostat;
6. expansion tank;
7. heater radiator;
8. controls.

1. "Water jacket" represents communicating cavities between the double walls of the engine in places where it is necessary to remove excess heat through the circulation of coolant.
2. Cooling system radiator serves to transfer heat to environment. The radiator is made from large quantity curved (nowadays most often aluminum) tubes with additional fins to increase heat transfer.
3. The fan is designed to enhance the flow of incoming air to the radiator of the cooling system (works towards the engine) and is turned on by means of an electromagnetic (sometimes hydraulic) clutch from the sensor signal when the threshold value of the coolant temperature is exceeded. Cooling fans with permanent drive from the engine are now quite rare.
4. Centrifugal pump (pump) serves to ensure uninterrupted circulation of coolant in the cooling system. The pump is driven from the engine mechanically: by a belt, less often by gears. Some engines, such as: turbocharged engines, direct injection fuel, can be equipped with a dual-circuit cooling system - an additional pump for these units, connected upon command from the electronic engine control unit when a threshold temperature value is reached.
5. Thermostat is a bimetallic device, less often - electronic valve, installed between the engine “jacket” and the inlet pipe of the cooling radiator. The purpose of the thermostat is to ensure the optimal temperature of the coolant in the system. When the engine is cold, the thermostat is closed and the coolant circulates “in a small circle” - inside the engine, bypassing the radiator. When the liquid temperature increases to the operating value, the thermostat opens and the system begins to operate in maximum efficiency mode.
6. Engine cooling systems internal combustion For the most part, they are closed systems, and therefore include expansion tank, compensating for the change in the volume of liquid in the system when the temperature changes. Coolant is usually poured into the system through the expansion tank.
7. Heater radiator- This is, in fact, a radiator of the cooling system, reduced in size and installed in the car interior. If the radiator of the cooling system releases heat to the environment, then the heater radiator releases heat directly into the cabin. To achieve maximum heater efficiency, the fence working fluid for him, it is carried out from the system in the “hottest” place - directly at the exit from the engine “jacket”.
8. The main element in the circuit of cooling system control devices is temperature sensor . Signals from it are sent to control device inside the car, the electronic unit control unit (ECU) with appropriately configured software and, through it, to other actuators. The list of these actuators, which expand the standard capabilities of a typical liquid cooling system, is quite wide: from fan control to relays additional pump in engines with turbocharging or direct fuel injection, the operating mode of the engine fan after stopping, and so on.

The principle of operation of the cooling system

Only a general, simplified scheme of work is given here. cooling systems internal combustion engine. Modern systems engine controls actually take into account many parameters, such as: the temperature of the working fluid in the cooling system, oil temperature, outside temperature, etc., and based on the collected data, they implement the optimal algorithm for turning on certain devices.